CO2 Does Not Drive Glacial Cycles

Guest post by Steven Goddard

There are still people who insist that changes in CO2 can explain the pattern of glacial and interglacial periods.  This article will present several arguments demonstrating that is incorrect, based on the ice core data below.
http://www.brighton73.freeserve.co.uk/gw/paleo/400000yearslarge.gif
Click for larger image

The most obvious reason is that CO2 lags temperature.  Changes in ocean temperature have driven the changes in atmospheric CO2, as explained here.  CO2 is not the driver.
Now consider the earth 20,000 years ago.  Temperatures were low – about 8C cooler than the present.  Due to the cold ocean temperatures, levels of atmospheric H20 (the primary greenhouse gas) were low.  CO2 levels were also low, at about one half current levels.  The earth’s albedo was very high due to extensive ice cover which had much of North America and Europe buried in ice.   Using the popular “CO2 and feedbacks explain everything” theory, all of these negative feedbacks should have driven earth further and further into an irrecoverable ice age.  Cold ocean water should have continued to absorb more CO2 from the atmosphere.

Atmospheric H2O should have continued to decline due to lower vapor pressures over the cooling oceans.  Albedo should have continued to increase due to expanding glaciers further from the poles.  All of these negative feedbacks should have caused temperatures to decrease further, and the death spiral should have continued.  But none of these things happened.  Instead, the earth warmed very quickly.  CO2 was absolutely not the driver, and positive/negative feedbacks had to be in balance.

Consider the earth 14,000 years ago.  CO2 levels were around 200 ppm and temperatures, at 6C below present values, were rising fast.  Now consider 30,000 years ago.  CO2 levels were also around 200 ppm and temperatures were also about 6C below current levels, yet at that time the earth was cooling.  Exactly the same CO2 and temperature levels as 14,000 years ago, but the opposite direction of temperature change.  CO2 was not the driver.

Now consider 120,000 years ago.  Temperatures were higher than today and CO2 levels were relatively high at 290 ppm.  Atmospheric H20 was high, and albedo was low.  According to the theorists, earth should have been warming quickly.  But it wasn’t – quite the opposite with temperatures cooling very quickly at that time.  CO2 was not the driver.
If CO2 levels and the claimed lockstep feedbacks controlled the climate, the climate would be unstable.  We would either move to a permanent ice age or turn into Venus.  Warmer temperatures generate more CO2.  Increased CO2 raises temperatures.   Warmer temperatures generate more CO2 …… etc.  It would be impossible to reverse a warming or cooling trend without a major external event.  Obviously this has not happened.

An exercise to get people thinking for themselves.  If the temperature at some point in the past was 4C cooler than now and CO2 levels were 240 ppm, was the temperature going up or down?  There are ten points on the graph that match those conditions.  Half of them have rapidly rising temperatures and half have rapidly falling temperatures.  It becomes abundantly clear that there has to be another degree of freedom which is dominant in controlling the glacial cycles.

In the ice core record, temperature drives CO2 – not the other way around.   Sometimes the earth warms quickly at 180 ppm CO2.  Other times it cools quickly at 280 ppm CO2.  Again, CO2 is not the driver of glacial cycles – there has to be a different cause.

UPDATE:

The use of the term “negative feedback” in this article is the commonly understood meaning – i.e. feedbacks that drive temperature down. Technically speaking, this usage is incorrect. From a viewpoint of semantics, a negative feedback would be one that works against the current trend. This semantic difference has no relevance to the logic being presented in the article.

About these ads
This entry was posted in Carbon dioxide, Climate_change. Bookmark the permalink.

158 Responses to CO2 Does Not Drive Glacial Cycles

  1. Nick Stokes says:

    Steve,
    Who are these people “who insist that changes in CO2 can explain the pattern of glacial and interglacial periods”? I don’t think they include any regular climate scientists that I know of. There is a view that CO2 provides positive feedback to a change already under way.

  2. Molon Labe says:

    “Atmospheric H2O should have continued to decline due to lower vapor pressures over the cooling oceans. Albedo should have continued to increase due to expanding glaciers further from the poles. All of these negative feedbacks should have caused temperatures to decrease further…”

    Ummm. Those are positive feedback mechanisms. The feedback signum refers to effect on signal amplitude, not the direction the signal changes.

  3. Steven Goddard says:

    Nick Stokes,

    Are you asking a serious question? The giant ice core graph was the centerpiece of Al Gore’s movie – in a clear, deliberate, unambiguous attempt to convince the audience that CO2 drives temperature cycles. Nearly every schoolchild in the world has been taught this concept.

  4. Mike Ramsey says:

    Nick Stokes (21:58:40) :

    Steve,
    Who are these people “who insist that changes in CO2 can explain the pattern of glacial and interglacial periods”?

    http://www.sciencemag.org/cgi/content/abstract/289/5486/1897

    “Hence, the 100,000-year cycle does not arise from ice sheet dynamics; instead, it is probably the response of the global carbon cycle that generates the eccentricity signal by causing changes in atmospheric carbon dioxide concentration.”

  5. Bill D says:

    My comment is bascially the same as Nicks. All of the science that I have read says that sun cyles drive the long term glacial cycles and that CO2 provides a positve feedback during the warming periods. It’s not just the simple solubility of CO2 in the oceans. Warming increases rates of bacterial degredation on land and in water, as well as making stronger thermal statification in the oceans. Thus, warming can lead to less CO2 burial in the ocean and more CO2 release from soils. Right now the tundra is a major reservoir of organic carbon. If warming and melting continue, releases from this source will increase.

  6. Didjeridust says:

    Of course there aren’t any of these people

    This is just a way of trying to give the simple minds among the readers here the impression that there actually is people in the “AGW camp”, the “Alarmists”, “Climate hysterics” or whaetever, that holds this view.

    “Science Blog of the year” – Yeah, right!

    REPLY:
    Actually, you got the title wrong. If you are going to criticize, at least do it correctly. – moderator

  7. Philip_B says:

    It’s a mystery why we do not get runaway warming or cooling (to a stable state) in the glacial/interglacial cycles.

    Something stops and then reverses the warming and cooling on a regular 100,000 year cycle. Although, the length of that cycle changed from about 50,000 years to a 100,000 years around a half million years ago.

    Milankovic Cycles have been proposed as the cause, but several problems exist with this (proposed) cause.

    http://en.wikipedia.org/wiki/Milankovitch_cycles#Problems

    BTW, the CO2 as feedback theory is nonsense.

    CO2 declines approximately linearly over the glacial phase of the cycle of about 80,000 years. And similarly it increases approximately linearly over the interglacial. This means CO2 will act as a negative forcing for about half of the time and most crucially for the first half of the glacial/interglacial period (when the two are averaged together).

    So rather than being a positive feedback, CO2 is forcing the temperature in the opposite direction to whatever is causing the warming and cooling glacial cycle for the first half of the cycle.

    In fact, if one were to ignore (the rather flimsy) evidence that increased CO2 causes warming and decreased CO2 causes cooling, CO2 looks to be a good candidate for driving the glacial cycle. Increasing CO2 progressively cools the climate, eventually overwhelming other positive feedbacks. Ditto for warming.

  8. Nick Stokes says:

    Steven
    Yes, it’s a serious question. Gore showed the plot, as many have done. His main point was that CO2 is now at a higher level than it was during that period. I don’t see anywhere where he said (let alone insisted) that it drove glacial cycles.

  9. Steven Goddard says:

    It is quite amusing seeing AGW defenders scrambling to claim that “no one believes” CO2 is the driver. It was the AGW camp who attempted to use the ice cores to prove their case, and now they are disavowing any knowledge.

    Al Gore stood in front of the giant Vostok Graph in his movie and said “there is one relationship that is far more powerful than all the others and it is this. When there is more carbon dioxide, the temperature gets warmer, because it traps more heat from the sun inside. “

    Has he issued a retraction to the hundreds of millions of people who saw the film and believe what he said?

  10. Stephen Brown says:

    According to the story at this link …

    http://www.telegraph.co.uk/earth/environment/climatechange/4734859/Scientists-capture-dramatic-footage-of–Arctic-glaciers-melting-in-hours.html

    … we don’t have to worry as the glaciers have just about disappeared already.

    REPLY: The title of that video is: ” Scientists capture dramatic footage of Arctic glaciers melting in hours”

    I watched the video to the end. What utter unmitigated rubbish. First it was shot and edited like a TV reality show. Second there was no before and after proof in the video imagery showing “a” glacier let alone “glaciers” melting in entirety within a hours, or even days. It’s nothing more than video showing something that happens regularly on glaciers and icefields with seasonal changes. They melt, water runs under them to the base. It is called a “moulin”. Unfortunately many will be drawn in by the slick editing and the danger faced by the intrepid scientists dangling over the abyss. Oh the danger, what brave scientists! Except, other than take a water speed measurement, there was no science in that video, just antics for the camera.

    A moulin is nothing new. Admiral (then Lieutenant ) Peary reported on it back in 1897 in the Journal of Geology. Read here.

    – Anthony

  11. Steven Goddard says:

    Molon,

    You are technically correct about the use of the term “negative feedback” but most people associate the term “negative feedback” with feedbacks which drive temperatures downward, and associate the term “positive feedback” with feedback that drives temperatures upwards.

    I don’t see anyone disputing the logic of the article – so can I take it that the AGW camp agrees that Al Gore’s film was misleading?
    .

  12. Nick Stokes says:

    Steven,
    If you want to establish your point, you only need to name those who believe that, and quote what they say. Your quote from Gore is just a standard, if a bit oversimplified, statement of the greenhouse effect. It’s not saying CO2 drives glacial cycles.

  13. Policyguy says:

    Steven,

    Well done.

    I’ve observed over the last several years that very few day-to-day climate change believers, whether strident AGW alarmists or just every day citizens who read papers and watch TV, have any comprehension of the real scientific issues that come into play in a discussion of what climate change is, has been or could be. One of my policy friends questioned me the other day whether we had ANY data, before satellites, to support contentions of medieval warming, the mini ice age or solar cycles going back 250 years. Another penned an email asking whether it was true that its getting cooler, not warmer, and what proof exists. Apparently this person had been exposed to someone who indicated that predicted higher temperatures were not occurring. These are highly educated people who populate high corporate and government public positions responsible for implementing climate change policies, who don’t have a clue about what constitutes climate change. These are people who accept a public consensus that climate change will lead to a host of unimaginably horrible things related to an ever warming planet caused by human waste and avarice, They don’t yet realize that the current CC movement is fueled by a global political – economic ideology, not scientific concern. Its amazing, but our entire national public policy apparatus is now focused on saving us from supposedly increasing global temperatures when our true public policy risk is abrupt cooling and the utter havoc that will cause.

    Your post is aimed at scientifically minded individuals familiar with glacial and interglacial cycles. I love it. Though I’m tempted to share your observations (and questions) with the people I cited above, to help educate them regarding the utter lack of scientific justification for our current craze, I hesitate because my fellow day-to-day climate change policy executives have no background to appreciate your observations and the implication of your logic. They have no conception that the IPCC reports are based on a “what if” premise of CO2 causation, rather than a scientifically based conclusion to a legitimate question about what was responsible for late 20th century warming.

    So, I take my hat off to you for your clearly written and well thought out post. But I offer the observation that those who understand your work are either part of the choir or, if not, understand that the well educated policy executives in high corporate and public policy positions responsible for implementing new climate change policies have no way to process this information and will not be affected by it. Over the last several years I have identified only three or four individuals, out of the many who populate high corporate and government policy positions, who could appreciate your work. How sad.

  14. Steven Goddard says:

    Nick,

    Al Gore’s claim is incorrect “there is one relationship that is far more powerful than all the others and it is this. When there is more carbon dioxide, the temperature gets warmer”

    The Vostok data (which he was standing in front of at the time) disproves his point. 120,000 years ago, CO2 levels were high and temperatures were cooling rapidly. 14,000 years ago, CO2 levels were low and temperatures were increasing rapidly.

    The Vostok data shows unequivocally that you can not make any prediction about the direction which temperatures are moving, based solely on the amount of CO2 in the atmosphere. Al Gore was wrong and has misled hundreds of millions of people. Still, he gets invited to give keynote speeches at AAAS.

    And let us not forget that during the Ordovician, CO2 levels were 10X current values, and earth had an ice age.

  15. cohenite says:

    Nick Stokes, the reasonable face of AGW pedantry; it is disingenuous to claim that a lack of CO2 doesn’t cause the ice-ages when AGW is premised on the hypothesis/fairy-tale that CO2 increases cause the opposite of the ice-ages; Arrhenius, who certainly thought a lack of CO2 would ice things up, is quoted with approval in Weart’s classic dystopic piece, “A Saturated Gassy Argument”;

    http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/

    Keep trying Nick, you may stumble onto something consistent in AGW eventually, even if it is the R2 correlation between CO2 increase and Gore’s increasing wealth.

  16. Steven Goddard says:

    Now let us focus on the other half of Al Gore’s statement.

    there is one relationship that is far more powerful than all the others and it is this. When there is more carbon dioxide, the temperature gets warmer

    The Vostok data again proves that is incorrect. The most powerful driver has to be something else besides CO2, because whatever is driving the glacial cycles has to overcome and reverse CO2 feedback, as well as H2O, albedo and other feedbacks – all of which are working against a reversal.

    Whatever drives glacial cycles must be a very strong force, and it is not CO2.

  17. Brendan H says:

    Steven: “There are still people who insist that changes in CO2 can explain the pattern of glacial and interglacial periods.”

    This sentence is badly worded. It appears to be claiming that some people regard CO2 as the sole or primary driver of both glacial and interglacial periods.

    It’s not clear who these “people” are, but the standard understanding of the change from a glacial to an interglacial period is that CO2 acts as feedback to a process – perhaps a change in the earth’s orbit — that sets off the initial warming that occurs at the end of an ice age.

    http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/langswitch_lang/in

    If you are arguing that CO2 was not the primary driver of past glacial/interglacial cycles, then you are in agreement with standard AGW theory. The difference between the glacial/interglacial periods and now are:

    1) We are not currently emerging from an ice age, and;
    2) CO2 is now considered to be acting as a forcing, not a feedback.

  18. Nick Stokes says:

    Steven,
    Gore did precede the quote you’ve given with the caveat “The relationship is very complicated.” And he went on to make a point that, in the context, was overly simplistic. But this falls a long way short of demonstrating your claim that: :There are still people who insist that changes in CO2 can explain the pattern of glacial and interglacial periods.”

    Mike Ramsay pointed to a 2000 Science article which does come close to making that claim. Although that is not so long ago, the author clearly was not aware of data showing the phase sequence of heating and CO2 rise – his claim is that both preceded ice volume changes. The IPCC AR3 in 2001 did say that CO2 lagged temperature, which pretty much settled this issue.

  19. Ozzie John says:

    Hi Nick,

    Maybe you could add your thoughts on what does drive the Glacial Cycles to support your viewpoint. If you don’t believe it’s CO2 then you would be more aligned with Steve’s post than with the AGW camp !

  20. len says:

    CO2 is a trace gas, the Atmospheric (incorrectly coined Greenhouse) Effect is not about infared this or that or insulation. It is about boundaries of convective zones (mass) of fluid. AGW violates what we understand of thermodynamics.

    How the physics of this whole area of study was supplanted with politics is a ‘case study’ in a sociology class.

    Whether that is science or not is another debate.

    As far as interglacials and glaciations go … how many people out there understand that we are at the end of an interglacial in what could be called a long ‘ice age’ and it could end at any time like it did many times in the Vostok record. My guess is we have a millenium before the Milankovitch cycle takes over. Not very long considering it took us this whole interglacial for mankind to start hitting his stride. We will need a few centuries like the 20th, in terms of technological development, to deal with evacuating most of North America, Europe, and Northern Asia. Evacuate may be the operative term given that some evidence, even this graph, indicates the onset can be very quick … even a decade. Now that would be a good ‘what if’ for a sociology class.

  21. One need to be cautious with drivers and feedbacks…

    Theoretically, there is a positive feedback of CO2 on temperature, as good as ice sheets and vegetation albedo changes are positive feedbacks on some inititial temperature change. To avoid any confusion: a positive feedback strengthens the initial change in the same direction, be it up or down.

    Does that mean that a positive feedback always lead to a runaway process? That depends of the feedback factor: As long as the feedback effect is smaller than the original forcing (feedback factor smaller than one), there is no runaway, but only a higher response than from the original cause alone.

    Is there a positive feedback of CO2 on temperature measured in the Vostok (or other) ice core(s)? No. Even a 40 ppmv drop at the end of the Eemian (the previous warmer (than current) period doesn’t show a measurable decrease of temperature, while a 3°C/2xCO2 should cause a drop of 0.5°C, according to current models:
    http://www.ferdinand-engelbeen.be/klimaat/eemian.html
    Temperatures (and methane) are already at minimum and ice sheets again at maximum when CO2 starts to drop, without measurable effect on temperature.

    The same is true for the warming from the LGM to the Holocene: There is a clear influence of temperature on CO2 levels, but no measurable influence of CO2 on temperature, as one should expect if CO2 is an important feedback:
    http://www.ferdinand-engelbeen.be/klimaat/klim_img/epica5.gif
    With thanks to André van den Berg, who provided the graph.

    Thus all together, the least one can say is that even if CO2 forms a positive feedback, that is not measurable in the ice cores and far overblown in current GCM’s…

  22. Mike D. says:

    I see no reason to single out Al Gore or even James Hansen. A vast army of people believe that CO2 forces global temperature increases. The CO2 Believers are planning “the largest mass civil disobedience for the climate in U.S. history” on March 2 in Washington DC. The Obama Administration is thick with such folks. It’s hard to find any politician that doubts that CO2 drives global temperature.

    And yet the ice record clearly shows that CO2 does not force global temps up or down. Temps fell when CO2 was high, and rose when CO2 was low, and vice versa. That factoid has been demonstrated numerously at WUWT (my personal favorite was the post by Frank Lansner last month).

    http://wattsupwiththat.com/2009/01/30/co2-temperatures-and-ice-ages/

    I know it flies in the face of The Consensus, but increased CO2 over the last ten years has been accompanied by falling global temperatures. Ipso facto, that theory is wrong. The ice record confirms that CO2 as the climate forcing GHG is bunkum, and in fact throws the entire GHG as a forcer of climate change into question, regardless of whichever GHG we’re talking about.

    It does no good, I know, to tell True Believers that the seas are NOT going to boil. Some folks are deeply invested emotionally as well as financially into the End of Creation hysteria. But I tell them anyway, not to bum their trip but out of a slim hope that logic will cure their madness.

  23. tty says:

    A few notes on the previous interglacial 120,000 years ago:

    The CO2 level was actually a bit higher than 290 ppm see:

    http://www.geol.lu.se/personal/MSR/bjerknes.pdf or:
    http://www.geol.lu.se/PERSONAL/DNH/images/RUN2005.pdf

    The ice-core record smooths out the short-term changes during the interglacials, and is probably systematically low at least during interglacials (stomatal index measurement give consistently higher results during the Holocene too) .

    The temperatures in northern Siberia were MUCH higher than today (on the order of 10 degrees centigrade) and forest extented to the Arctic coast, but no noticeable CH4 release resulted, nor did it during earlier warm interglacials. This strongly suggests that this particular feedback is imaginary.

    About the Ordovician glaciation. Not only did it occur at a time of much higher CO2 levels, it may well have been the most severe during the Cenozoic. It is the only glaciation to have caused a mass extinction.

  24. John Edmondson says:

    Also the cyclicity of glacial/interglacial is a crucial point. The ice ages are driven by 3 interacting astronomical variables.
    1.These are the variation of the earth’s orbital eccentricity. The eccentricity varies between 0 , a perfect circle, and 0.1, at these times the earth sun distance varies between 88 and 98 million miles. Cycle length = 100,000 years
    2. Axial inclination , this is currently 23.5 degrees, but can vary between 22.5 and 24.5, cycle length = 41,000 years.
    3. Precession of the equinox, this is the variation of the seasons compared with the calender. i.e. in the NH summer solstice occurs in June, but in 13,250 years time NH summer solstice occurs in December. Cycle length = 26,500 years.
    An Ice age will happen when the above parameters cause reduced solar heating in the NH summer. Permanenet Snow and Ice moves south , increasing the earth’s albedo. This positive feedback continues to reduce temperature until the ice covers all of Canada, the Northern part of USA large parts of Europe. Typically the average temperature is 5 degrees below what we see today.
    Ice ages are a lot easier to start than to end. The is why glacial/interglacial times spans are typically 100,000/20,000 years.
    To end an Ice age the sun would have to a maximum heating effect to melt the Ice and reduce the albedo. To do this the axial inclination would have to be near 24.5 degrees, NH summer solstice sun distance near to the minimum of 88 million miles.
    2 other points.
    Ice ages are a NH only, antartica has little or no influence on this.
    Carbon dioxide varies during Ice ages, but is not the driver.

  25. foinavon says:

    Mike Ramsey (22:34:44)

    Your selective quoting of a sigle sentence of Shackleton (2002) misrepresents the theme of the article. Shackleton and the science of 2000 in general recognised the dominant role of Milankovitch cycles as the primary drivers of ice age glacial-interglacial cycles. The question was what factor(s) amplify the rather puny changes arising from variations in insolation due to changes in orbital eccentricity.

    A previous study (Imbrie) had proposed that the temporally primary amplification was ice sheet dynamics (albedo feedbacks). Shackleton (the paper you linked to) analyzed deep sea sediments and the new glacial core records to infer a phasing of drivers (Milankovitch orbital eccentricity) and amplifiers (CO2; ice sheet albedo responses) and concluded that the primary amplifier of the weak orbital eccentricity was CO2 rises in advance of albedo effects through ice sheet dynamics.

    So Shackleton (2000) can’t really be “recruited” to support the straw man “argument” of the top post. Then as now, the evidence supports CO2 and albedo effects as the primary amplifiers of the orbital variations that drive the ice age cycles (we’d probably reinstate ice age dynamics a little more prominently nowadays since we have a better handle on the relative timings of responses now).

    Nicholas J. Shackleton (2000) The 100,000-Year Ice-Age Cycle Identified and Found to Lag Temperature, Carbon Dioxide, and Orbital Eccentricity Science 289, 1897 – 1902

  26. mugwump says:

    Steven Goddard,

    How can you be so simplistic as to take Al Gore’s claims on face value?

    “there is one relationship that is far more powerful than all the others and it is this. When there is more carbon dioxide, the temperature gets warmer”

    Clearly, what Al meant depends upon what the meaning of the word “is” is.

    [/sarc]

  27. Roy says:

    Molon was absolutely right about the negative/positive feedback distinction, and if anyone is going to use that term they should either use it properly or make it explicit that they using it colloquially (i.e. wrongly).

    It’s not a mistake I would make and I immediately tune out when I see someone else making it. It is a big deal–almost worth blogging about.

  28. E.M.Smith says:

    Bill D (22:35:08) : All of the science that I have read says that sun cyles drive the long term glacial cycles

    I assume you meant to say ‘insolation cycles due to orbital mechanics’ since solar cycles don’t have any known 100,000 or 40,000 year periodicities…

    Warming increases rates of bacterial degredation on land and in water, as well as making stronger thermal statification in the oceans. Thus, warming can lead to less CO2 burial in the ocean and more CO2 release from soils. Right now the tundra is a major reservoir of organic carbon. If warming and melting continue, releases from this source will increase.

    And what about the effect of growing 25 to 50 TONS per acre per year of plants (as demonstrated in Eucalyptus, Willow, and Poplar groves)? Hmm? How about that 40% increase in growth rate demonstrated from higher CO2 levels?

    Please balance your CO2 books on plant dynamics. Warmer and higher CO2 results in much greater biosequestration over most of the earth surface. Look beyond the tundra…

    Yes, this matters a great deal. Just where do you think all that coal and oil came from in the first place… See peat bogs for a modern example of the process still at work.

  29. Ellie in Belfast says:

    The one question we need to ask is this –

    “Can the climate get COOLER when there are high(er) levels of CO2 in the atmosphere?”

    This needs to be asked – and answered – clearly, loudly and often. The answer, clearly and unequivocally, from historical data, is YES.

  30. Allen63 says:

    I question if the historic interglacial CO2 peaks were in the 290 range (as on the graph). The ancient atmospheric CO2 has not been directly measured. Rather, ice core measurements have been “adjusted” by a “factor”. I question the “factor”.

    Could be that current CO2 levels are not any higher than recent ancient interglacial levels. A bit OT for this thread, but it is something I think about every time I see that graph.

  31. Archonix says:

    So, here I am lurking around, not being particularly scientifically minded (leaning toward Psychology rather than a hard science because that’s just how my mind works) and I see statements like Nicks, and wonder…

    You see, the last 20 years of the AGW hype have been premised on the idea that CO2 drives the climate. To state, now, that this has never been stated in the precisely worded way Nick asks for is rather like turning to a large haystack and saying “But there isn’t a straw in there that’s exactly 111.762 mm with a diameter of 16 mm, therefore the entire haystack doesn’t exist”.

    It’s a clever bit of obfuscation to say that nobody has made a precise statement but it rather misses the point; the claim has been that CO2 drives climate. The proof is lacking, and the claim falsified by the data.
    Back to lurking!

  32. John Philip says:

    We look forward to Mr Goddard’s next post where, having single-handedly shown how the world’s assembled climate and coral experts are mistaken he goes on to demonstrate that chickens cannot actually lay eggs because the chickens ‘lag’ the eggs… :)

    The same argument was advanced by Viscount Monckton, and the counterargument elegantly expressed by Dr Stephan Harrison, Senior Lecturer in Physical Geography at the University of Exeter

    He says that during glacial/interglacial transitions, increases in atmospheric C02 follow rather than precede warming, and argues that this nullifies the present causal link between high levels of CO2 and observed warming. Of course it doesn’t. Warming at glacial/interglacial timescales is driven by orbital forcing, with C02 playing an important feedback on global temperatures. This is entirely different to the situation that exists today, where changes in insolation amounts or patterns are insufficient to explain the warming we see. Either Monckton knows this (in which case his arguments should be dismissed as pure propaganda) or he doesn’t know this, in which case his understanding of the science is woeful.

    Are we getting hung up on semantics here? Historically CO2 does not ‘drive’ the changes in temperature, in the sense of initiating them, but does act as a powerful feedback once they are underway, which explains the ‘lag’. Not a difficult concept really.

    Others adressing the issue include the Royal Society see misleading argument No 3,, RealClimate, (read the letter by Professor og Geosciences Jeff Severinghaus) its a New Scientist Climate Myth, and it is currently No 11 in the skeptical science list of arguments.

    Reply: Tone it down ~ charles the moderator

  33. foinavon says:

    Steven Goddard (00:06:50)

    It’s worth putting back Gore’s previous sentence from that part of his film you quoted from:

    The relationship is very complicated. But there is one relationship that is more powerful than all the others and it is this. When there is more carbon dioxide, the temperature gets warmer, because it traps more heat from the sun inside.

    Of course it would have been better if Gore had said “all else being equal, when there is more carbon dioxide, the temperature gets warmer….”. That would accord with scientific understanding. In any case I suspect that everyone that is interested in this subject will know that orbital variations “drive” the ice age cycles and are amplified by CO2/albedo (and water vapour!) feedbacks.

    A more serious point is your assertion:

    And let us not forget that during the Ordovician, CO2 levels were 10X current values, and earth had an ice age.

    That’s rather “Gore-like” in its omissions! First it’s incorrect since we simply don’t know what the CO2 levels were at the time of the late-Ordovician glaciation nearly 450 million years ago.Unfortunately we don’t have any paleoCO2 proxies contemporaneous with that event. Secondly it’s very well characterised that the solar constant was around 5% weaker then (late-Ordovician) than now, and so the threshold for significant glaciation was much higher then than now. So whereas widespread glaciation can occur on Earth now with CO2 levels around/below 500/600-ish ppm of CO2, during the late-Ordovician greenhouse gas levels would have to be much higher (greater than 2000 ppm and perhaps as high as 3500 ppm CO2 [***]) to suppress significant glaciation.

    e.g. D. L. Royer (2006) CO2-forced climate thresholds during the Phanerozoic Geochimica et Cosmochimica Acta 70, 5665–5675

  34. Nick Stokes says:

    Roy and Molon: I absolutely agree – proper use of the term negative feedback is important.
    On feedback Ferdinand gives a good summary too, until it comes to GCM’s and modern times. Now CO2 is not a feedback – it’s a forcing. We’re injecting it into the atmosphere.

    Ozzie John and cohenite – foiunavon above has summarised the standard theory of Ice Ages. AGW theory doesn’t say that past warmings were caused by CO2, and I don’t believe they were. It just says that the present unique circumstances, in which large amounts of fossil carbon are being added to the atmosphere, will cause warming.

    In fact CO2 change was never a good explainer of Ice Ages. It would only raise the question – what drives the CO2 change (then)?

  35. Philip Mulholland says:

    A Centifugal governor is a mechanical device that automatically determines the power output of a steam engine and is an example of system control via negative feedback http://en.wikipedia.org/wiki/Centrifugal_governor

    The phrase “Dangerous negative feedback” is an oxymoron with a dissemblance rating of genius level.

  36. Smokey says:

    John PhiliP quotes:

    …the situation that exists today, where changes in insolation amounts or patterns are insufficient to explain the warming we see.

    What warming?

    CO2 is a minor forcing agent, overwhelmed by other factors. Our planet is proving it to those who simply open their eyes: click

  37. David Porter says:

    Nick Stokes (03:41:51) :

    “In fact CO2 change was never a good explainer of Ice Ages. It would only raise the question – what drives the CO2 change (then)? ”

    How about temperature?

  38. David Porter says:

    John Philip (03:24:53) :

    Are we getting hung up on semantics here? Historically CO2 does not ‘drive’ the changes in temperature, in the sense of initiating them, but does act as a powerful feedback once they are underway, which explains the ‘lag’. Not a difficult concept really.

    Explain the concept please because I find it difficult. The difficulty I have is that I feel I have to believe it before I can understand it. Would that be correct?

  39. Nick Stokes says:

    David Porter
    How about temperature? Well, it’s temperature that you’d be trying to explain, so that won’t do. Although it’s not too far off – heat vaporising CO2 which causes heating … is the kind of positive feedback mechanism which can promote oscillation from relatively weak drivers. But you still need a driver – orbital aberrations have the right kind of frequency.

    I think the role of CO2 in this kind of feedback should not be overstated – water vapor is probably more significant.

  40. DocMartyn says:

    ” Bill D (22:35:08) :
    Thus, warming can lead to less CO2 burial in the ocean and more CO2 release from soils.”

    O.K., on the last point; where and when did the carbon become entrapped in the soil?

    Organic material is sequestrated in the soil during growth, are you suggesting that during a cold period there is more entrapped, which is released when things heat up?

    Can you model the time-line for the entrapment of carbon and its release on the same time scale as presented by the author.

  41. mugwump says:

    John Philip (03:24:53) :

    Historically CO2 does not ‘drive’ the changes in temperature, in the sense of initiating them, but does act as a powerful feedback once they are underway, which explains the ‘lag’. Not a difficult concept really.

    The whole point John is that the “powerful feedback” part is entirely unproven. The Stefan-Boltzmann law gives a very weak feedback effect of about 1 degree for doubling of CO2. Anything beyond that requires invoking even more powerful feedbacks such as water vapor, and discounting potential negative feedbacks such as clouds.

    Steven’s post illustrates this nicely: if CO2 was such a powerful feedback then how come the ice core record shows that it seems to be almost completely overwhelmed by other effects?

    The simple fact is we still have very little understanding of the relative strengths of the different feedbacks and how they are influenced by the climate state, despite Al Gore’s and the alarmist industry’s vociferous claims to the contrary.

  42. Dorlomin says:

    Steve Goddard has excelled himself again. Posts like this will have all those so called ‘scientists’ quaking in their boots!

  43. Alexander Harvey says:

    Here is a longer Benthic Carbonate reconstruction:

    http://en.wikipedia.org/wiki/File:Five_Myr_Climate_Change.png

    Visually I notice the appearance of greater variance or amplitude with lower tempertures.

    Is this real or an artifact of the reconstruction? Anyone know?

    If it is not an artifact then does it imply that the climate is more stable when temperatures are warmer? (Less positive feedback?)

    If so, does that imply Climate Sensitivity has declined with increasing temperatures?

    These are not statements, just questions; as I sure do not know. If it is an artifact it needs sorting as it is very suggestive of a real difference in the temperature stability between warm and cold periods.

    Alexander Harvey

  44. Tim L says:

    Looks like a place to post this, note 100,000 years pattern in graft.

    The Fermi telescope and NASA’s Swift satellite detect “in the order of 1,000 gamma-ray bursts a year, or a burst every 100,000 years in a given galaxy,”

    http://news.yahoo.com/s/afp/20090219/sc_afp/sciencespaceastronomy;_ylt=AgMlEZoKo9cB4K9JUXloNxVxieAA;_ylu=X3oDMTE5djBmdHJiBHBvcwMzBHNlYwN5bi1tb3N0LXZpZXdlZARzbGsDaHVnZWdhbW1hLXJh

  45. Bill Illis says:

    For the opposite point of view on CO2 and the ice ages …

    You have to read Hansen’s latest paper published recently in Open (Access) Atmosphere Science Journal (but was rejected by Science and even NASA would not put out a news release on it)).

    The long list of coauthors includes all the paleoCO2 experts.

    He is bumping up the long-term equilbrium warming estimate to +6.0C for a doubled CO2 based on his current understanding of how the ice ages work, the now-slower-than-thought ocean thermal response time, the causes of the Antarctic glaciation (now I know why foinavon keeps bringing this up) and the Eocene thermal maximum.

    Here is the full paper.

    http://www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf

    The published one is here (just small changes and authors added).

    http://arxiv.org/abs/0804.1126

    Basically, warming will be slower than originally thought, but most of the ice sheets will still melt and the albedo feedback from the lack of ice will push us to +6.0C from a doubled CO2 within 1,500 years.

    This all depends on his current understanding of how the ice works and his misunderstanding of Pangani’s CO2 estimates during the Antarctic glaciation.

  46. redneck says:

    tty (01:45:59)

    The Ordovician occured during the Palaeozoic era.

    M White (03:50:08) :

    “Wrapping Greenland in reflective blankets”

    I wonder if academics, like Dr. Box, ever think about the practical aspects of their proposals. It does explain why academics, like Dr. Box, should remain in institutions and not venture into the private sector.

  47. Steven Goddard says:

    What the Vostok cores show is that there is 0% correlation between CO2 levels and the direction the temperature is moving. You can pick any CO2 level on the graph, and find an equal number of points where the temperature is going up, and where it is going down. This is the exact opposite of what Al Gore was claiming.

    As far as Dr. Hansen goes, he put this claim in his Illinois Wesleyan presentation.
    Chief instigator of climate change was earth orbital change, a very weak forcing.
    http://www.columbia.edu/~jeh1/2008/illwesleyan_20080219.pdf
    This claim is self-contradictory. The “chief instigator” would have to be the strongest influence in the system, because it has to be able to overcome the combination of all of the other feedbacks in order to reverse the direction which the temperature is moving. 15,000 years ago CO2 was low, H20 was low, and albedo was high – yet the temperature started rising quickly. Changes in the earth’s orbit had to be able to overwhelm the combination of CO2 forcing + H2O forcing + albedo forcing, all of which were working to lower temperature further at the time.

  48. Steven Goddard says:

    I taught a class of 10 year olds on Friday. The class was not about global warming, but one of the children raised the subject.

    If you want the names of people who believe that Al Gore’s giant CO2 graph proves that rising CO2 leads to rising temperatures, go to any public school and talk to the brightest children. They all have been brainwashed to believe this.

    Whether or not AGW is a serious concern, the Vostok graph tells us nothing about it. All that it shows is that there is a relationship between temperature and CO2 levels.

  49. Steven Goddard says:

    For clarity, I asked Anthony to add the following addendum to the article, but I don’t know if he is busy with CA today.

    The use of the term “negative feedback” in this article is the commonly understood meaning – i.e. feedbacks that drive temperature down. Technically speaking, this usage is incorrect. From a viewpoint of semantics, a negative feedback would be one that works against the current trend. This semantic difference has no relevance to the logic being presented in the article.

  50. george h. says:

    There is no evidence in any timescale: decadal, century, milenial or geologic that CO2 levels significantly contribute to temperature change. The satellite records show this, the ice core data shows this as do longer geologic records.

    As many have observed, as CO2 levels have continued to rise over the last decade, temperatures have fallen contrary all GCM expectations. The 20th century showed no consistent relationship between the two with periods of increase and decline over the period. As others have pointed out on this thread, careful (nonGoreon) analysis of the ice core data fail to demonstrate the defensive CO2 amplification position.

    During the Cretaceous and Jurassic geologic periods CO2 levels were as much as 5 times greater than the current levels — no tipping point there! During the Miocene the world was about 10°F warmer and the CO2 concentration was significantly less. During the Pleistocene CO2 increases were accompanied by global cooling.

    Historic and geologic data are inconsistent with GW theory. Imagine what climate scientists would be saying were it the other way round — it the world really looked like their discredited models.

  51. Todd Snigg says:

    As a lurker here interested in the subject (AGW) I think its important to point out that while AGW scientists may not believe that the CO2 is the ‘primary driver’ of rising temperatures, the ‘public relations department’ of AGW theory proponents is putting out something completely different. Chock it up to our sound-bite culture, but to those of us outside the circle of the ‘settled debate’ it sure seems like the primary talking point is something along the likes of:
    “We’re killing ourselves with CO2, now stop eating beef, buy a Prius, ride a bike to work, and don’t breathe hard while doing it.”
    Typically the people saying this then get back into their Gulfstream G-IV and jet off to the next city to say the same thing to another group of people. After buying their carbon-credits to off-set the trip, of course.

    So maybe what you (AGW scientists) have is more of PR problem. But it sure seems like the debate is anything but ‘settled’.

    Just one man’s opinion.

    Todd

  52. Philip_B says:

    Let’s assume John Philip is correct,

    Historically CO2 does not ‘drive’ the changes in temperature, in the sense of initiating them, but does act as a powerful feedback once they are underway,

    If CO2 is a powerful positive feedback during the warming part of the glacial/interglacial cycle, then it must be an equally powerful negative feedback at equal concentrations during the cooling part of the cycle.

    Which means there must be an even more powerful positive feedback (or forcing) overcoming CO2 during the cooling phase.

    The even more powerful feedback is then mysteriously absent during the warming phase. This is a far too ad hoc explanation for me.

  53. len says:

    Bill Illis notes that Hansen says in a recent paper,

    “Basically, warming will be slower than originally thought, but most of the ice sheets will still melt and the albedo feedback from the lack of ice will push us to +6.0C from a doubled CO2 within 1,500 years.”

    So a trace gas with trump the Milankovitch cycle. How silly is this going to get.

    What I’m interested in now is does our ‘ice age’ (interglacials and glacials … all relatively cold) that we live in correspond to the length of time the Super Massive Black hole in the center of the galaxy has been asleep?

    http://biocab.org/Carbon_Dioxide_Geological.jpg

    http://www.pbs.org/wgbh/nova/blackhole/program.html

    No time for Hansens paper, the politics of AGW is getting boring … and my Jack Russel wants to play.

  54. Chris V. says:

    Steven Goddard (06:07:38) :

    What the Vostok cores show is that there is 0% correlation between CO2 levels and the direction the temperature is moving. You can pick any CO2 level on the graph, and find an equal number of points where the temperature is going up, and where it is going down.

    You seem to have a misunderstanding of the term “forcing”. The forcing is the CHANGE in net irradiance at the top of the atmosphere, relative to some reference level.

    250 ppm of CO2 could be a positive forcing (causing temperatures to increase), if CO2 levels 500 years earlier were 200 ppm. Or 250 ppm of CO2 could be a negative forcing if CO2 levels 500 years earlier were 300 ppm. This is exactly what your graph shows.

  55. tallbloke says:

    Alexander Harvey (05:07:27) :

    Here is a longer Benthic Carbonate reconstruction:

    http://en.wikipedia.org/wiki/File:Five_Myr_Climate_Change.png

    Visually I notice the appearance of greater variance or amplitude with lower tempertures.

    Is this real or an artifact of the reconstruction? Anyone know?

    If it is not an artifact then does it imply that the climate is more stable when temperatures are warmer? (Less positive feedback?)

    If so, does that imply Climate Sensitivity has declined with increasing temperatures?


    A very good question. Perhaps the more stable temperatures 45M years ago when it was warmer than now suggest that higher temperature is closer to the earth’s long term optimum. Maybe if we had a study of a period with much higher temperatures at a similar resolution we might see bigger amplitude variance there too. Of course, the optimum might change with the distribution of the landmass. As might the degree of variance at other temperatures. Greater biomass may have a greater dampening effect on temperature swings too.

    Complicated innit? :o)

  56. srchuck says:

    Regardless of one’s persuasion concerning what CO2 actually forces, one must agree that changes in H2O force more.

    Regardless of what one believes about the validity of paleoCO2 data, one must agree that when the planet was 8C cooler, the atmosphere contained much less H2O vapor, and that H2O vapor change slightly lags temperature change.

    If a<b, then why are we hung up on a? If “greenhouse effect” is of serious concern, we should be principally concerned about the increase in pan humidity associated with the trends in irrigation over the last century.

    Or, perhaps both are of small import as “greenhouse” gases, in support of the thesis of this thread (though I believe it can be shown that other properties of water are strong drivers of the glacial cycle…a topic for another thread).

  57. Gary Pearse says:

    A couple of (very) cold winter (certainly in Canada and apparently in Europe) in the face of growing CO2 can’t scientifically be used as evidence of AGW supporters being wrong. However, the general public and our news media up here have quietened on the subject (BBC is an exception – maybe they need to turn their thermostats down). Also, the global warming “consensus” is feeling the need to fight rearguard actions – although still showing confidence in their hot world scenarios, we are beginning to see the semantic phase: “oh we didn’t actually say that”… “of course there will be temporary reversals” (Dr. Hansen predicted a world record temperature being recorded in the next 2-3 years and this was two years ago … I apologize for not having the exact links but it is in Hansen’s blog in a few places) … “oh dear, the ice extent sensors have underestimated ice extent by half a million sq km…. the Hadley Centre (weather people in UK), once leading champions of AGW are now telling the media to temper down their extravagant AGW rhetoric. … And what about slurs against WUWT:

    Didjeridust”

    “This is just a way of trying to give the simple minds among the readers here the impression that there actually is people in the “AGW camp”, the “Alarmists”, “Climate hysterics” or whaetever, that holds this view.

    “Science Blog of the year” – Yeah, right!”

    Like the feedbacks and forcings of CO2, we are likely to see the same type of forces at work in the debate going forward. Dr. Hansen and others are already extending the “best before” date by several decades. If the AGW consensus turns out to be wrong, don’t expect any mea culpas. What happens to these types of debates if they go wrong is that gradually they melt away around the edges and those who have taken the most irretrievable stances die of old age.

    Let us be grateful for WUWT it is one of the better avenues for preventing the “consensus” from closing off debate. Its award is well deserved, witness the fact that the heavyweights in the AGW feel the need to respond immediately to damaging posts – degraded satellite sensors (NSIDC), Norways Nansen group explaining downward revisions of ice extent, NASA’s quick response to errors in measuring world temp (mixing months in the record) . Both sides of the debate facilitated here is clearly read religiously every day. They have handed out Nobel Prizes for much less than this.

  58. Pamela Gray says:

    But Steven, the AGW scientists are now saying that CO2 is both a negative and a positive feedback mechanism as well as a forcing. So regardless of the initial natural cause of a temperature change in the past, CO2 will make it worse, whether it goes up or down. So if it is going up, CO2 will make it go up more. If it is going down CO2 will make it go down more. If we have new circumstances and temperature was stable and perfect (IE no natural forcings in action), a sudden change is initially caused by and made worse by CO2, which explains the dire circumstances we are now in, and yes, even when it gets colder instead of warmer. I know it is complicated and there are other far more educated scientific web sites that will help explain this to you.

    There is work afoot to replace burying nuclear reaction waste (a deadly substance that only due diligence by knowledgeable people have saved us from) with sequestered CO2 instead because it is such a harmful gas. I tell ya. If they hadn’t banned that substance in hairspray, we would all be dead now from skin cancer. Nuclear waste and CO2 are just as deadly. We should be thanking these people instead of childishly arguing with them;

  59. Alexander Harvey (05:07:27) :

    Visually I notice the appearance of greater variance or amplitude with lower tempertures.

    Is this real or an artifact of the reconstruction? Anyone know?

    If it is not an artifact then does it imply that the climate is more stable when temperatures are warmer? (Less positive feedback?)

    Indeed, climate is more stable during warm periods than during cold one’s. That has to do with albedo: the change of land from vegetation to ice sheets and back is a very strong feedback in both directions, which strengthens any small change in orbital caused insolation. But that is a lot less when most of the ice sheets are already melted, thus less feedback in warmer periods.

    And clouds may be involved as temperature regulator, once the vapor pressure reaches a maximum (like hurricanes forming when seawater reaches 28°C, dissipating energy to cooler places and to space).

    About CO2 as “strong” feedback: The ice ages indeed show that CO2 is NOT a strong feedback, as no effect is measurable from 40 ppmv drop at the end of the Eemian, neither any response from temperature on CO2 changes during the LGM-Holocene transition. Thus CO2 is NOT a strong driver of temperature either, even if we are responsible for the 100 ppmv increase in the past 150 years.

    The average 3°C/2xCO2 of the current GCM’s is already much too high, let it be the 6°C/2xCO2 proposed by Hansen e.a. This is not supported by evidence form the ice cores.

    Hansen was the first to introduce the 3°C/2xCO2, because he missed a feedback factor, as the ice ages – interglacials show a larger temperature variation than calculated from albedo changes. Thus CO2 must give a strong feedback. But any other feedback (an underestimate of the albedo feedback or of cloud feedback – nobody knows the cloud cover of the ice ages…) could do the job as well.

  60. Sandw15 says:

    Steven Goddard’s statement,
    “Whatever drives glacial cycles must be a very strong force, and it is not CO2.”,
    describes the crucial issue in climate change. I’ve been following this debate since the mid 90’s and it seems to me that the discovery of the CO2 lag in the Vostok cores marked a drastic turning point in the debate.
    If I remember right, in the 90’s AGW proponents were adamant that Milankovitch cycles were not significant drivers of climate change. Their arguments regarding Milankovitch cycles seemed valid at the time and still seem valid now. In other words, the Milankovitch cycles seem inadequate to provide climate forcing sufficient to overcome the proposed theoretical influence of CO2. Now, the AGW crowd seem to love Milankovitch cycles. Am I imagining this? Memory plays tricks.
    Solar variability continues to be denied as a factor in the AGW arguments. If one accepts their earlier arguments regarding Milankovitch cycles and their continuing arguments involving solar variability then there is a clear implication of some other factor not currently identified. This factor is capable of causing large rapid shifts in temperature. It seems that any prudent researcher concerned with the effects of rapid climate change would be giving some thought to this possibility. Um…the precautionary principal would seem to suggest that somebody ought to be covering that base. Of course, this presumes that the researchers are really concerned about the future well-being of humanity.
    Anyway, is the following statement true? There is an unknown factor which causes large worldwide temperature swings but climate scientists are not interested in finding out what it is.

  61. Bill Illis says:

    I found and downloaded the CO2 and Temperature data over the last 100 million years from Berner, Pagani and Zachos (all coauthors on Hansen’s latest paper) and plotted these on the same graph.

    As you can see, the temperature and CO2 history of the planet is complicated. While there is a small correlation between temperatures and CO2, there is much more reason to believe this link is not very strong and there are often very contradictory trends in the two measures.

    CO2 is certainly not the main driver of temperatures.

    Those of you who have spent some time at Global Warming Art looking at separate historical CO2 and Temperatures plots will want to see this.

    http://img10.imageshack.us/img10/4364/tempvsco2100m.png

  62. Bill Yarber says:

    The ice core data goes back over 400,000 years but how far in the past do they stop or become unviable and force us to use actual CO2 measurements? Since CO2 concentrations are significantly higher today than in any of the ice core data, is there a problem with melding measured CO2 values with ice core values? Is there degradation in the CO2 levels appearant in the ice cores that we are not ajusting for? Or has man really pumped out so much CO2 that we truly are in a whole new ball game and this time it is different? Being a CO2 sceptic, I don’t think so, but this chart shows gives me a better understanding why some people do.

    Bill

  63. thefordprefect says:

    Look there is NO coloquial use of the term “negative feed back” – it can only have one meaning. Feed back that reduces the effect of disturbances.
    E.G. wiki:
    Negative feedback feeds part of a system’s output, inverted, into the system’s input; generally with the result that fluctuations are attenuated. Many real-world systems have one or several points around which the system gravitates. In response to a perturbation, a negative feedback system with such point(s) will tend to re-establish equilibrium.

    There is the negative feedback on ebay – with a different meaning.

    I have not seen it used to mean negative forcing until the misuse in the Telegraph article and here.

    If technical authors do not understand this what hope is there?

    Mike

  64. beng says:

    If the CO2/methane/temp changes had been in lockstep (the greenhouse radiational effects are instantaneous), it prb’ly would’ve convinced me & alot of others that CO2 drives climate.

    Wonder if the phrase “we gotta get rid of those ice-core time lags” was ever uttered?

  65. Alexander Harvey says:

    Bill,

    Thanks for the link to the Hansen paper.

    Now I am struggling a little with his use of the words forcing and feedback (slow and fast).

    Now CS is defined in terms of temperatures and radiative forcings and those forcings are defined in terms of Net Irradiance.

    Now the net irradiance changed little betwen the LGM and the Holocene, he states that equilibria existed in both periods. So only true forcings (effects not due to the change in temperature) can be included in the calculation. The sun and GHG that changed from some other reason than temperature.

    Feedbacks (effects due to the change in temperature should not be included).

    I would have thought that would have ruled out most or all of the -3.5 figure (ice ,veg, etc) and the CO2 part of the -3 figure leaving about 0.75 W/m^2 as the forcing giving a CS of ~6 degC/(W/m^2) or ~20C per CO2 doubling,

    Now I can see what he is saying, he has two points on the NI(T) function [Net Irradiance function] seperated by 6.5 W/m^2 and 5 degC and he draws a straight line between them and extropolates to higher temperatures which is okay if that straight line represents physical reality but if in getting from A to B the CS =1/NI(T) was nearly vertical their is no justification of the extrapolation.

    I will be willing to accept that people may have a very different concept also called CS but I think the argument will still hold but would require many more words to explain.

    Alexander Harvey

  66. Robert Rust says:

    Al Gore’s movie ends with, “Are you ready to change your life?” What does Mr. Gore ask you to change? Reduce your “carbon footprint.”

    My son’s 9th grade science teacher stated emphatically that AGW was real, humans are going to kill the planet unless we stopped the carbon.

    I, for one, have taken a modified version of the Al Gore pledge. I promise to try to be successful enough to put as much carbon into the air as Mr. Gore does. Heated swimming pools, world wide travel, exotic foods flown in for large parties – must be fun.

    —-
    Mr. Goddard takes hard data, points out interesting patterns that indicate that CO2 simply can’t be “the thing” that drives the temperature. Nick, et. al. focus on the few comments regarding the “who” in the public discussions and not on the “what”. I wonder why that is.

  67. Alexander Harvey says:

    Oops correction,

    Having used the term Net Irradiance I went on to use it where I shouldn’t of:

    Now I can see what he is saying, he has two points on a flux function F(T) seperated by 6.5 W/m^2 and 5 degC and he draws a straight line between them and extropolates to higher temperatures which is okay if that straight line represents physical reality but if in getting from A to B the CS =1/F(T) was nearly vertical their is no justification of the extrapolation.

    Such is life!

    Alex

  68. Steven Goddard says:

    Sandw15,

    Excellent comments!

    Chris V,

    You are now proposing that the polarity of CO2 forcing is dependent is dependent on CO2 levels “500 years earlier?” You better call up your local climate modeler and explain that to him, because I can assure you that GCM radiative transfer models do not have any component of distant past CO2 levels as part of their calculation.

    thefordprefect,

    You apparently have no disagreement with the logic, as you have decided to pursue a nonsensical argument around semantics. Negative is normally interpreted as making things smaller. (You may remember that from primary school mathematics.) This could mean the trend gets smaller, or it could mean the temperature gets smaller. In this case of a declining temperature regime, the meanings are opposite.

    The problem with the BBC segment was that the term “negative feedback” was used incorrectly by either definition. I’m sure you think you are being clever, but rest assured – you are not.

  69. Jeff says:

    george h. wrote:
    “As many have observed, as CO2 levels have continued to rise over the last decade, temperatures have fallen contrary all GCM expectations. ”

    If temperatures have fallen over the last decade, why were all the years since 2000 warmer than 1999?

  70. Bill Yarber (08:48:47) :

    The ice core data goes back over 400,000 years but how far in the past do they stop or become unviable and force us to use actual CO2 measurements? Since CO2 concentrations are significantly higher today than in any of the ice core data, is there a problem with melding measured CO2 values with ice core values? Is there degradation in the CO2 levels appearant in the ice cores that we are not ajusting for? Or has man really pumped out so much CO2 that we truly are in a whole new ball game and this time it is different?

    The ice core data are going back to 800,000 years nowadays. There is no adjustment of the ice core data necessary, the bubbles still contain the atmosphere as it was many thousands of years ago. If there was diffusion of CO2 through the ice, the CO2 measurements would level out over time, but the oldest and youngest glacial/interglacial ratio remains the same.

    And yes, we have pumped twice the amounts of CO2 into the atmosphere than what is measured in ice cores and the atmosphere (with an overlap of about 20 years for the Law Dome ice cores). The other halve is sequestered by oceans and the biosphere.

    If the increase has a real (or even dangerous) impact, that is the multibillion euro(*) question.

    (*) because of the devaluation of the dollar some expressions need an economic upgrade…

  71. Smokey says:

    Jeff:

    If temperatures have fallen over the last decade, why were all the years since 2000 warmer than 1999?

    You’re confusing an anomaly with the trend.

    Here’s the trend: click [the green line]

  72. Policyguy says:

    Sandw15,

    “Anyway, is the following statement true? There is an unknown factor which causes large worldwide temperature swings but climate scientists are not interested in finding out what it is.”

    If a “climate” scientist is someone whose research has benefited by the AGW theory, then, in my opinion you are correct. One merely accepts AGW and proceeds to calculate the impact on whatever piece of science may be their specialty. Just climb on the hay wagon and sing to the tune. Who cares why the worldwide temperature swings.

    Those interested in finding out what “it” is are people like Steven and yourself.

    But look what Al Gore and the IPCC did. I stand in awe. They trumped difficult to understand and oftentimes contradictory science and packaged their overly simplistic version of it in snippets that support their desired new socio-economic model. Now we have a world of lemmings following the Goracle.

    So Steven, keep it up. Perhaps at some point we will have a Goracle too, but one who understands how to extract the CO2 following temperature information in your plot, as well as the logic that shows that temperatures move up and down in grand steps through the same CO2 concentrations, and who can communicate with nine year olds around the planet, who can then teach their parents.

  73. Richard Sharpe says:

    I think that the next thing the Academic-Political complex will tell us is that CO2 production leads to runaway coolening, so they have to tax us for it.

  74. Chris V. says:

    Steven Goddard (09:46:19) :

    Chris V,

    You are now proposing that the polarity of CO2 forcing is dependent is dependent on CO2 levels “500 years earlier?” You better call up your local climate modeler and explain that to him, because I can assure you that GCM radiative transfer models do not have any component of distant past CO2 levels as part of their calculation.

    No, you misunderstood me. I was commenting on this statement you made:

    What the Vostok cores show is that there is 0% correlation between CO2 levels and the direction the temperature is moving. You can pick any CO2 level on the graph, and find an equal number of points where the temperature is going up, and where it is going down.

    The DIRECTION the temperature is moving depends on the CHANGE in the CO2 forcing. As long as your starting temperature is near equilibrium, increasing CO2 will cause temperatures to rise, and decreasing CO2 will cause temperatures to fall.

    The ABSOLUTE CO2 levels do not determine the temperature TREND. The CHANGE in the CO2 levels does.

  75. Jeff says:

    Smokey wrote:
    “You’re confusing an anomaly with the trend.”

    If you start your line at 1999 instead, you will get a positive slope to your green line. Or at 1997. All you’re doing is cherry-picking the years that give you the result that you want.

  76. The “Oxbridge Harvard consensus” has said for decades, that while CO2 does not make the ice ages start to end, it presently kicks in to amplify the warming. “Popular consensus” says “Science shows that CO2 amplifies”, a mantra without a shred of proof. RealClimate gives the mantra, without a shred of proof; popular consensus quotes RealClimate.

    On the other hand, Frank Lansner and friends here at WUWT recently showed many things we can see in the shape of the graphs alone that DO amount to evidence that gives the lie to the mantra. Lansner used a composite of the last 4 Ice Ages, an excellent way to bring out the shared patterns, cut out the noise, and make the basics easy to grasp. Ah, but this lacks the comfort value of “Science Shows…”

    Check my Climate Science primer on this

  77. Smokey says:

    Jeff

    You cite the year 1999 — and then you accuse me of cherry picking??

    OK then, take your pick of whatever time series you want. Any time series from 6 years ago, to 4.6 billion years ago:

    click1

    click2

    click3

    click4

    click5

    click6

    click7

    click8

    click9

    click10

    click11

    click12

    click13

    click14

    click15

    click16

    click17

    click18

    click19

    click20

    Face it, the planet is cooling. And FYI, global cooling does not mean global warming. It means global cooling.

  78. Leon Brozyna says:

    Frankly, as a slightly literate layman, the whole business of CO2, AGW, tipping points, et al strikes me as nothing more than simple primitive tribal superstition dressed up in fancy modern verbiage. The incessant barrage of media presentations on global warming seem to create the impression that all the changes that are occurring can be attributed to mankind’s evil industrial activities. Repent all ye sinners for ye have unleashed the evil CO2 god and he is wrecking havoc on the beneficent Gaia.

  79. RICH says:

    CO2 does not drive ice-out conditions on our lakes either…

    Here is a link for ice-out data on Lake Winnipesaukee, New Hampshire, dating all the way back to 1887.

    http://www.winnipesaukee.com/index.php?pageid=iceout

    Some cherry picking here, but if you look at the actual data, there is absolutley no reason [whatsoever] to be concerned of an impending climate catastrophy:

    Ice-out for 1921 was March 28.
    Ice-out for 1998 was April 7.
    Ice-out for 1889 was April 14.
    Ice-out for 2001 was May 2.

    http://me.water.usgs.gov/iceout_data/Data.Winnipesaukee.txt

    The only thing that stands out here was cooling during the 60s and 70s, which some people claim was a “lie”. Everyting else seems normal.

    My conclusion. Man-made global warming is a grossly exagerated hoax.

  80. Simon Evans says:

    A few questions for you, Steven:

    1. Does increasing CO2 increase IR absorption or not (regardless of by how much, to what effect, etc. – I just want to know whether it does, yes or no)?

    2. Are changes in ice albedo positive feedbacks to temperature change (by “positive feedback” I mean what anyone who understands feedbacks would mean)?

    3. If so, do such changes in albedo lag the initial change in temperature in the record of the glacial cycles?

    4. If they do, and if you recognise that albedo changes are positive feedbacks, and that thus they amplify changes in temperature, why do you seek to reject the positive feedback of CO2 changes because it lags the initial temperature change (as any feedback is bound to do, of course)?

    5. Have areas of ice extent been at a given level when the albedo change has been amplifying cooling and at the same given level when albedo change has been amplifying warming? The direction of change is what is important, is it not, rather than the absolute level?

    I will be interested, as always, to see whether you can give me straight answers to these straight questions.

    REPLY: Simon I don’t like your tone, suggesting the respondent won’t give “straight answers” while asking the questions is disingenuous. I grow tired of your attitude toward other participants. [self snip] – Anthony

  81. DocMartyn says:

    “Jeff (11:51:54) :

    Smokey wrote:
    “You’re confusing an anomaly with the trend.”

    If you start your line at 1999 instead, you will get a positive slope to your green line. Or at 1997. All you’re doing is cherry-picking the years that give you the result that you want.”

    How dare you suggest that Smokey is a climate Scientist.

  82. Roger Knights says:

    “that is the multibillion euro(*) question. (*) because of the devaluation of the dollar some expressions need an economic upgrade…”

    It’s the Euro that’s devaluing:
    http://seekingalpha.com/article/120922-trouble-brewing-in-europe-could-send-eur-usd-to-2-yr-low

  83. Simon Evans says:

    Anthony,

    REPLY: Simon I don’t like your tone, suggesting the respondent won’t give “straight answers” while asking the questions is disingenuous. I grow tired of your attitude toward other participants. [self snip] – Anthony

    In which case, I suggest you ban me from your site.

    I note, again, that you are quick to object to the tone of a poster challenging the argument of one of the items on this site whilst you have not objected to the tone coming from ‘the other side’ (for example, SG’s response to a post above: “I’m sure you think you are being clever, but rest assured – you are not”, not to mention all the other scornful and defamatory remarks that are churned out on this site every day).

    I have asked for a straight answer since I have asked the question before and not received one.

    I do not know why you consider my questions ‘disingenuous’. Are you suggesting that I am engaging in Socratic irony? Well, that could only be the case if you presume the ignorance of the person I am questioning, so that’s a matter of your interpretation and not mine.

    But as I say, if you don’t like my tone then do what you wish. If, however, you wish to maintain the sense of fair access to debate, then I suggest you should be looking at some other people’s tone in advance of mine.

    REPLY: Thanks for illustrating my point. Your quest for a “straight answer” demonstrates your expectations of it. Thus any answer given that does not meet your expectations will be criticized by you, no matter if it is factually correct or not. That is what is disingenuous about your approach. As for others, the question is about you. And since you are not a moderator, you have no benefit of knowing what comments make it here or not. Again you draw only on your beliefs- Anthony

  84. Simon Evans says:

    Anthony,

    Thus any answer given that does not meet your expectations will be criticized by you, no matter if it is factually correct or not.

    That is completely untrue. I will not criticise factual statements. I think you are drawing on your own beliefs there, if I may say so.

  85. Simon Evans says:

    [removed - see most recent comment from Anthony]

  86. wattsupwiththat says:

    Simon- I decided after looking further that the term had different meaning in Britain than in the US, (I thought of it as comical and about pretentiousness and a US reference agreed, but the meaning is different in Britain) so I withdraw it indicated by [self snip] and comments related to it, with my apology.

  87. Chris V. (11:42:14) :

    The DIRECTION the temperature is moving depends on the CHANGE in the CO2 forcing. As long as your starting temperature is near equilibrium, increasing CO2 will cause temperatures to rise, and decreasing CO2 will cause temperatures to fall.

    The ABSOLUTE CO2 levels do not determine the temperature TREND. The CHANGE in the CO2 levels does.

    The different feedback definitions used here makes this more complicated than necessary, but temperature change is the cause and CO2 is the feedback, not reverse over the ice ages, until recently. Thus indeed a fixed point of CO2 in the past doesn’t say anything about the influence of one on the other, as a feedback only can work after an initial change, not a steady state of the primary factor.

    Thus the answer on the five questions of Simon Evans is yes, but as important is the answer to the question “is CO2 causing an important feedback” and there the answer, based on the same ice cores is no…

  88. Greg says:

    Regarding Simon’s post just above.
    If the “direction of change is what is important… rather than the absolute level” then you haven’t properly identified the mechanism that is driving the effect. You need to ask the question “what is driving the direction of change”?
    Perhaps you could plot the derivative of CO2 over time. If it turns out d(CO2)/dt correlates well with temperature without the lag, then there are two sensible conclusions: temperature causes change in CO2; or something else directly causes both temperature change and CO2 direction change simultaneously.

  89. Chris V. says:

    Ferdinand Engelbeen (15:25:43) :

    Thus the answer on the five questions of Simon Evans is yes, but as important is the answer to the question “is CO2 causing an important feedback” and there the answer, based on the same ice cores is no…

    How do the cores show that?

    Everything shown in the graph in the OP is completely consistent with CO2 acting as a positive feedback to an initial warming (or cooling) caused by Milankovich cycle albedo changes.

  90. Greg says:

    Regarding Simon’s post just above.
    If the “direction of change is what is important… rather than the absolute level” then you haven’t properly identified the mechanism that is driving it.
    Perhaps you could plot the derivative of CO2 over time. If it turns out d(CO2)/dt correlates well with temperature and without the lag, then there are two sensible conclusions: temperature causes change in CO2; or, something else directly causes both temperature change and CO2 direction change simultaneously.

  91. kent says:

    Simon Evans (12:42:41) :

    A few questions for you, Steven:

    1. Does increasing CO2 increase IR absorption or not (regardless of by how much, to what effect, etc. – I just want to know whether it does, yes or no.

    The answer to this question is both yes and no. Yes if there is more IR that has not been absorbed and no if there is none left to be absorbed.
    The data that I have seen indicates that most IR in the frequencies available to CO2 is already being absorbed. Where there is some left is at the poles.
    I question the reflectivity of ice. Ice is clear and transparent. It is snow and shatered ice that is reflective. (Think of an ice rink before anyone is on it. Once they rip it up it becomes white and reflective.)
    We keep seeing life under meters of sea ice. Sunlight penetrates the ice with no problem, powering the food chain. This light is not reflected.
    When sea ice melts it takes thermal energy out of the water below it. When open polar water warms it stays on the surface but when polar water cools it sinks out of site. We get to see the warm water because it stays on the surface but what happens to the water that cools and sinks?

  92. Robert Bateman says:

    If tomorrow, the Sun dropped it’s output and turned Red, it would be as if there were an eclipse or volcano every day. The Earth would cool rapidly, the oceans would start holding more CO2, and neither the Temperature or the CO2 levels would have an effect larger than zilch on the Sun. You could belch all the CO2 from all the coal plants you could feed, but it wouldn’t save the planet from having it’s photosynthesis asphyxiated, nor would it warm the planet 1/10th of a degree. In a billion years, the Earth would look like Mars.
    Frozen desert.

  93. thefordprefect says:

    Steven Goddard (09:46:19) :
    The technical meaning of the word feedback is important especially when there is an adequate word “forcing” which could have been used. But I will let it rest here.
    I was not trying to be clever nor was I trying to duck the information you posted. Below I give you some analysis of my own which SEEMS to show that entry and exit from ice ages is caused by GHGs. I offer no PROOF as I was not there at the time. But the data is not mine and has not been doctored.
    The data for the following “analysis” is from:
    http://www.ncdc.noaa.gov/paleo/icecore/antarctica/domec/domec_epica_data.html
    EPICA Dome C Ice Core Data
    I have been through entry and exit from most ice ages/cold periods and have noted the age that either CH4 or CO2 have significant changes. In most cases this occurs just before or at the same time that temperature change occurs and is acting as a green house gas.
    There is one strange temperature dip at around 722000 ybp which is not explained by a GHG change.
    Exit from ice age CH4 CO2 17500ybp
    http://img15.imageshack.us/img15/562/iceageco2ch450018500my5.jpg
    Entry to ice age CH4 128500ybp
    Exit from ice age CH4 CO2 136000ybp
    http://img15.imageshack.us/img15/4554/iceageco2ch4100150gt7.jpg
    Entry to ice age CH4 CO2 242000ybp
    Exit from ice age CH4 CO2 24900ybp –too early?
    http://img16.imageshack.us/img16/5796/iceageco2ch4220260yh6.jpg
    Entry to ice age CH4 (CO2) 333000ybp
    Exit from ice age CH4 34300ybp
    http://img17.imageshack.us/img17/8106/iceageco2ch4300350nn4.jpg
    Entry to ice age CH4 (CO2) 406000ybp
    Exit from ice age CO2 432000ybp
    http://img18.imageshack.us/img18/4103/iceageco2ch4360450lh8.jpg
    Entry to ice age CO2 CH4 489000ybp
    Exit from ice age CO2 CH4 531000ybp
    http://img22.imageshack.us/img22/9684/iceageco2ch4460550dz0.jpg
    Entry to ice age CH4 566000ybp
    Exit from ice age CO2 583000ybp
    Entry to ice age CH4 CO2 611000ybp
    Exit from ice age CO2 CH4 629000ybp
    http://img23.imageshack.us/img23/9392/iceageco2ch4540650om1.jpg
    Entry to ice age CH4 695000ybp
    Exit from ice age ———-
    Entry to ice age ———
    http://img27.imageshack.us/img27/634/iceageco2ch4650740et7.jpg
    Exit from ice age CO2 740500ybp
    http://img7.imageshack.us/img7/4350/iceageco2ch4710750fx5.jpg
    Entry to ice age CH4 (CO2)786000ybp
    http://img14.imageshack.us/img14/8453/iceageco2ch4750800kz4.jpg
    Mike

  94. Chris V. says:

    kent (16:53:41) :

    The CO2 absorption bands are only partially saturated in the lower atmosphere.

    In the cold upper atmosphere there is CO2, but almost no water vapor, so there is still plenty of outgoing radiation at the wavelengths absorbed by CO2.

  95. Larry Kirk says:

    A good post. Thanks Stephen. The comments with links to longer term climate and CO2 data are also particularly interesting. We have far more to fear from an ice age than a repeat of the Eocene. Everything dies in an ice age.

    I think that commentators’ well-intentioned fears of the politico-scientific indoctrination of our children may be a little overblown though. The children that I know seem to have very short attention spans, and an acute distaste for hectoring political agenda in adults. When I dutifully took my 13 year old son to see ‘An Inconvenient Truth’, when it first came out here, he sat through it with an expression of execrable boredom, and then when we came out from the movie and I asked him what he had thought of it, he turned to me and through gritted teeth said: “We did that at school three years ago!” It had about as much interest for him at thirteen as a party political broadcast by the Conservative party or an interminable, droning grammar school religious assembly had for me at the same age. So I apologised embarrasedly and we went and had something interesting to eat instead.

  96. Policyguy says:

    Larry,

    I tend to agree with your assessment of kids’ attention. In the real world, it is adults who accept the more simplistic “everyone agrees” dogma and in the public policy arena, act on it. More often than not, these individuals do not have a technical background and shy away from independent conclusions.

  97. Philip_B says:

    Interesting that methane seems to lead the temperature falls. I didn’t see an example of leading temperature increases.

  98. Philip_B says:

    climate is more stable during warm periods than during cold one’s. That has to do with albedo: the change of land from vegetation to ice sheets and back is a very strong feedback in both directions, which strengthens any small change in orbital caused insolation.

    I agree that plant albedo together with water vapour levels from plant transpiration are probably the most important feedbacks.

    Still dosn’t explain the warming and cooling cycle though.

  99. flyfisher says:

    I’m a developmental geneticist by trade, so I must admit I don’t understand many of the terms/data used in the more detailed posts. However, what I do understand is that there is no way in hell that CO2 can be anything but a minor player in the warming of the earth. CO2 levels have risen unabated for quite some time now, yet we have not seen a similar increase in temps. The past several years have all been flat. And don’t give me this garbage about needing to measure things over time or 5-10 years is much too short a period to use for predictions. Nonsense. Either it works or it doesn’t. If I increase the cellular level of a particular protein I will probably get a known, consistent response. If I decrease a proteins’ levels I will probably get a known, consistent response. If I get nothing then I can say, without a doubt, that increasing or decreasing the protein’s expression does not affect the cell. If CO2 continually absorbs IR and traps heat, and more CO2 will do the same, how can you explain the fact that temps have NOT gone up to keep pace with CO2? Is this not evidence that there is another, stronger player(s) in heating/cooling the earth?

  100. Steven Goddard says:

    Chris V,

    Your statement is partially incorrect. LW radiation is not trapped at any level of the atmosphere as your post implies.

    The sum total of incoming and outgoing LW+SW radiation is essentially zero, minus changes in oceanic heat content. The effect of increased greenhouse gases is to increase the frequency of absorption/re-radiation events, as LW radiation works it’s way back out into space. But rest assured, all of the LW radiation finds its’ way out.

    In order to maintain equilibrium of incoming and outgoing radiation, an increase in greenhouse gases requires that atmospheric temperatures increase, or a decrease in greenhouse gases requires that temperatures decrease. That is the greenhouse effect.

    This image is a good one to explain how the equilibrium works. Note that outgoing is exactly equal to incoming. 30% of incoming SW radiation is reflected, and the other 70% is returned to space as LW.
    http://www.aer.com/images/rc/heattrap_thumbb.gif

  101. Syl says:

    “So whereas widespread glaciation can occur on Earth now with CO2 levels around/below 500/600-ish ppm of CO2…”

    then why-o-why are people so adamant we have to get back to 280 or so and that the 380 we currently have is close to or beyond a ‘tipping point’? We are currently STARVED of co2 and 280 is dangerously low for the health of life as we go into the next glaciation. I have seen NO studies that quantify the loss of life as CO2 was depleted from the atmosphere as the globe cooled. All scientists have been interested in is extinctions! Well, if a few individuals of a species survive and therefore don’t go extinct that doesn’t make killing off most of them due to co2 starvation okay does it?

    This makes the one-sided arguments of warmers rather specious and empty.

  102. Chris V. (16:32:28) :

    If you look at the detailed graphs, one sees a lagged response of CO2 on temperature, but no response of temperature on CO2, with or without a lag. The moment that CO2 levels drop with 40 ppmv, ice sheets start to melt and temperature goes up at the end of the Eemian (the previous warmer interglacial), neither does temperature accelerate upward when CO2 increases during the LGM-Holocene warming. Thus the least one can say is that the feedback of CO2 is (far) less than the over 30% of the feedback (with 3 K/2xCO2) that current models “predict”.
    See:
    http://www.ferdinand-engelbeen.be/klimaat/eemian.html
    and
    http://www.ferdinand-engelbeen.be/klimaat/klim_img/epica5.gif

  103. Mark T says:

    Simon, you said:

    2. Are changes in ice albedo positive feedbacks to temperature change (by “positive feedback” I mean what anyone who understands feedbacks would mean)?

    4. If they do, and if you recognise that albedo changes are positive feedbacks, and that thus they amplify changes in temperature, why do you seek to reject the positive feedback of CO2 changes because it lags the initial temperature change (as any feedback is bound to do, of course)?
    Anyone that truly understands the concept of feedback also understands that the terms positive or negative have nothing to do with amplification or attenuation. I suggest you take a course on control theory if you want to understand why this is.

    Mark

  104. kent (16:53:41) :

    I question the reflectivity of ice. Ice is clear and transparent. It is snow and shatered ice that is reflective. (Think of an ice rink before anyone is on it. Once they rip it up it becomes white and reflective.)

    Ice sheets are always covered with snow, at least during cooling and cold(er) periods. Snow has a high reflectivity for visible light and is a very good emitter for IR waves. So it cools much faster and reflects far more sunlight than vegetation. Add to that the water vapor feedback in a warming or cooling climate and you have a strong feedback in both directions, with or without GHGs.

  105. thefordprefect says:

    There are a couple of occasions (up to 500kybp) where ch4 could lead temperature rise –
    343kybp occurs 2ky before rise so only a possibility
    430kybp occurs 1ky after start of rise.

    I’m not sure what the accuracy of the dating is will look it up later.

    A thought (not a theory!) co2 causes temp rise. methane released from once frozen tundra. co2 released from sea. Temp rise amplified. methane exhausted. half life in atmosphere 7 – 10 years. methane levels fall. co2 insufficien forcing to maintain temp. temp drops.

  106. Nick Stokes says:

    Anyone that truly understands the concept of feedback also understands that the terms positive or negative have nothing to do with amplification or attenuation.
    That’s absurd. Amplification is exactly what feedback (and its sign) is about. From Wiki:
    Negative feedback feeds part of a system’s output, inverted, into the system’s input; generally with the result that fluctuations are attenuated.
    In contrast, positive feedback is a feedback in which the system responds in the same direction as the perturbation, resulting in amplification of the original signal instead of stabilizing the signal.

  107. Syl says:

    “Everything shown in the graph…”

    That’s the key because NOT everything is shown in the graph. I’ll give you a hint: it beings with ‘w’.

  108. Joel Shore says:

    And don’t give me this garbage about needing to measure things over time or 5-10 years is much too short a period to use for predictions. Nonsense. Either it works or it doesn’t.

    Is this not evidence that there is another, stronger player(s) in heating/cooling the earth?

    Good point. And, another “theory” that these climate scientists perpetuate is the idea that there is this thing called the “seasonal cycle”! According to this theory, it should now be getting warmer in Rochester, NY as the Northern hemisphere is heading toward what the proponents of this unproven hypothesis call “summer”. However, a couple weeks ago in Rochester, we had some warm weather but now it is very cold again. In fact, there has been a clear downward trend over the last couple of weeks. The seasonal cycle proponents gives us some garbage about needing to measure things over a longer time period. But, I say, “Nonsense!” Either it works or it doesn’t!

    Is this not evidence that there is another, stronger player than the seasonal cycle in heating/cooling the earth?

  109. John Galt says:

    If CO2 doesn’t drive climate change, then what’s the point?

  110. Mark T says:

    Nick Stokes (02:00:26) :
    That’s absurd. Amplification is exactly what feedback (and its sign) is about. From Wiki:
    Negative feedback feeds part of a system’s output, inverted, into the system’s input; generally with the result that fluctuations are attenuated.
    In contrast, positive feedback is a feedback in which the system responds in the same direction as the perturbation, resulting in amplification of the original signal instead of stabilizing the signal.

    Unlike you, I learned my control theory from a textbook and many, many hours of study towards a few degrees, not Wikipedia. “Positive” and “negative” refer to the sign applied to the feedback term, nothing more, Nick. Try not to be so ignorant of the facts and re-read that quote, in particular the part that says “Negative feedback feeds the part of a system’s output, inverted,…” In other words, NEGATIVE means the feedback is INVERTED, or in simpler terms, negated.

    Get off your collective high horses. You guys really do not understand these concepts.

    Mark

  111. Mark T says:

    Oh, and, btw, if you would care to get into a discussion of the gain of a system we can go there too. For a simple single pole system:

    y(n) = x(n) + ay(n-1)

    the transfer function for a positive results in a gain of 1/(1-a) for lowpass signals. Test #1: figure out why. For a negative, the gains works out to be 1/(1-a) for highpass signals. Test #2: figure out why. Both have gain and attenuation, but it is frequency dependent.

    That’s what happens when you read the Wiki and think you understand what is, to any engineer, basic concepts.

    Mark

  112. Mark T says:

    I should add, a must be less than unity for stability.

    Mark

  113. foinavon says:

    Mark T (07:41:51)

    Mark you have to be a little careful applying words definitions and concepts from one scientific field (control theory in engineering for example) to another (climate; Earth’s energy “budget”) where the meanings of words may not be exactly the same.

    In fact control theory, while an excellent subject, is not the most appropriate analogy for addressing the Earth’s energy budget arising from changes in forcings, since this doesn’t really contain predominant elements of “control”. In fact, the effects of changes in forcings is probably best understood in relation to changes in the equilibrium temperature that results from changes in the forcings with amplifications due to feedbacks.

    So, for example, any enhanced atmospheric warming (from enhanced solar irradiation, for example, or enhanced greenhouse gas concentrations) results in a water vapour feedback that can be expressed mathematically to give a total response that is similar to the form of the equation you posted:

    e.g. If the solar change (or enhanced greenhouse forcing) results in a 1 oC change, and the resulting water vapour feedback adds an additional x of additional warming then the total warming from the primary forcing (enhanced solar or greenhouse) + water vapour feedback is something like 1 + x + x^2 + x^3 + x^4 …

    which is 1/(1-x).

    The result is an amplification of the effect of the primary forcing and the shift of the earth’s equilibrium temperature to a new (higher) value. Obviously the water vapour feedback doesn’t “feedback” to affect the solar forcing (it does have a slight “engineering style” feedback into the CO2 forcing since enhanced warming recruits a small amount of additional CO2 from ocean/terrestrial sources).

    One can add in albedo feedbacks which are also positive feedbacks. These will result in an enhanced amplification of the temperature response to the primary forcing, whether in a warming or cooling direction. One needs also to consider the extent to which the various feedbacks (amplifications) are, or are not, effectively self-limiting. For example the albedo feedback may be dominated by the retreat (in a warming world) of sea ice, but once the ice retreats back to the continental margin, the contribution of the albedo feedback will wane.

    In short the use of the term “feedback” must be considered in relation to the subject at hand. We are interested in the thing and not the word that may be used to describe it!

  114. Nick Stokes says:

    “results in a gain of 1/(1-a) ”
    This is true whether a is positive or negative (which determines whether the feedback is positive or negative). In your system, the open loop gain is 1. And if a is negative the gain is less than 1 (attenuated); if a is positive but less than 1, the gain is greater than 1 (amplified). Exactly what Wiki, Simon and I are saying. And if you want to introduce frequency dependence, the phase shift just makes a complex, but doesn’t really change the principle.

    BTW, I did not learn these ideas from Wiki. I have a PhD in mathematical control theory.

  115. Jeff Alberts says:

    A thought (not a theory!) co2 causes temp rise. methane released from once frozen tundra. co2 released from sea. Temp rise amplified. methane exhausted. half life in atmosphere 7 – 10 years. methane levels fall. co2 insufficien forcing to maintain temp. temp drops.

    Are there ice core plots of Methane and temp?

  116. jack mosevich says:

    OT but intresting: an article about 385 million year old tree fossils. Next-to-last paragraph:

    This was also a significant moment in the history of the planet. The rise of the forests removed a lot of Carbon Dioxide from the atmosphere. This caused temperatures to drop and the planet became very similar to its present-day condition.”

    Link: http://www.sciencedaily.com/releases/2007/04/070418130435.htm

  117. Mark T says:

    foinavon:

    I understand the climate science perversion of the word, and it stems from a lack of understanding of basic control theory, whether they are consistent or not. However, I was directly addressing Nick’s assertion which was in direct reference to the control theory use of the word feedback, which he clearly misread (he chided me for saying negative referred to the sign of the feedback term, yet failed to notice that the Wiki quote actually agreed with me!).

    As to the rest of what you state, it is immaterial to my point (and quite frankly, not in contradiction to what I said, either). Control theory still applies, even if they (climate scientists) do not use it correctly. As I noted, it is frequency dependent. Their perverted used of the term is actually correct if the proper frequencies are noted (which depends upon the delay in the feedback path). To date, I have not seen anyone that quotes the Wikipedia article demonstrate a clear understanding of this, however.

    And, I disagree that the term “feedback” must be considered in relation to the subject at hand, or at least, that the subject is not at least fundamentally still control theory at its heart. Terminology is invented so that people that understand the theory are able to communicate with each other. I understand that there is no “control” in this particular system (though any self-regulating systems has some measure of “control”), but that does not mean that the analysis methods and terminology does not apply.

    Mark

  118. gary gulrud says:

    “Now CO2 is not a feedback – it’s a forcing.”

    All right, a feedback in AGW-speak changes the amplitude, got it. So one can’t model more than quadratic functions? Seems that a forcing could go negative in non-linear systems.

  119. gary gulrud says:

    “The ABSOLUTE CO2 levels do not determine the temperature TREND. The CHANGE in the CO2 levels does.”

    So a forcing is a derivative, and a feedback is an exponent?

    I am reminded of Wittgenstein’s maxim that most philosophical conundrums are founded in a confusion over the limitations of language, particularly the fact that ambiguity cannot be avoided, proven axiomatically by Goedel.

    The idiocy that is AGW is unavoidably enabled and continued thru climate jargon.

  120. gary gulrud says:

    “cold upper atmosphere there is CO2, but almost no water vapor”

    I doubt this, CO2 is poorly mixed in AIRS data, heavier than air and freezes like H2O in the “cold upper atmosphere”.

    “so there is still plenty of outgoing radiation at the wavelengths absorbed by CO2.”

    This does not follow in any case. If only 1% of IR reaches the ground from the Sun why should the reverse direction be different?

  121. Nick Stokes says:

    he chided me for saying negative referred to the sign of the feedback term” Really? Where?
    As I said above, frequency dependence does not change the basic properties of positive/negative feedback. In your expression the gain is 1/(1-a). Taking account of phase shift (so a is complex), it’s still the case that if the real part of a is negative, the absolute value (magnitude) of gain is less than one; conversely, if the real part is positive (but less than 1) the absolute value of gain is positive.

    I don’t see how climate scientists are getting this wrong. In fact, there’s an earlier comment on this thread by Bill Illis criticising a recent Hansen paper in which he continues to carefully examine the lags in the feedback response.

  122. Mark T says:

    Um, no, a is not complex, a is a constant in my example. Again, you express your ignorance of the subject matter.

    Sorry, but you are completely off base when you say “frequency dependence does not change the basic properties of positive/negative feedback.” Look up the phrase “bode analysis.” While you’re at it, perform a frequency response of these two equations, one positive and one negative:

    y(n) = x(n) + 0.9*y(n-1),
    y(n) = x(n) – 0.9*y(n-1)

    clearly frequency matters, contrary to your ill-informed opinion. Shall I post plots of the responses? When you mention 1/(1-a) and then apply +/- a to the gain you are doing it incorrectly. 1/(1-|a|) is actually the result (sorry if that was not clear), in one case at DC in the other at higher frequencies (depends upon the delay element in your equation).

    I don’t see how climate scientists are getting this wrong.
    Because YOU don’t understand. Listen, Nick, you know yourself that you don’t have a background in this, yet you continue to argue it from a position of ignorance, why?

    Mark

  123. Mark T says:

    I should point out that the equations above would need to be generalized into continuous time variables rather than discrete. It’s just easier to visualize using discrete equations. Discretization merely causes the “spectrum” of the analysis to repeat at intervals of the sampling period.

    Mark

  124. Mark T says:

    Constant a would imply a linear feedback, i.e., a constant slope. A logarithmic response would show up as a slowly decreasing value for a, approaching zero, or no more feedback.

    Mark

  125. Wondering Aloud says:

    Way to not read carefully.

  126. Fred2 says:

    Steve’s thesis, that CO2 does not force (initiate) glaciation cycles, stands. That is, changes in CO2 have not caused changes between glacial and interglacial periods.

    So this at least limits the power of CO2 to change climate. And one cannot use the glaciation history to “Prove” the power of CO2.

    All of this, by itself, does not disprove AGW. But it is up to the AGW proponents to prove their theory, it is not the burden of anyone else to disprove AGW unless it was previously considered proven.

  127. Wondering Aloud says:

    What is clear from the ice core data is two fold

    1. Carbon dioxide trails temperature and so can not be the primary cause as it would violate causality.

    2. The idea that temperature increase releases carbon dioxide is reasonable but the second part that this amplifies the signal is clearly not supported by the data in fact the shape and timings of the peaks and cooling portions of the graph falsify this hypothesis as well.

    I see reason to think carbon dioxide should help warming however the ice core data really doesn’t support it.

  128. Wondering Aloud says:

    You may want to check on what Leif has been saying on various threads here. His field is solar astronomy and he seems to be able to argue convincingly that solar variability doesn’t match the record either.

    It isn’t that we know why the climate is varying, I am just darn tired of being told that we do. Things like “an inconvenient truth” do significant harm to science as a whole and as a result to society.

  129. Wondering Aloud says:

    How strong is the evidence that the orbital cycles people keep mentioning are in fact the cause of the glacial cycles? I only ask this because until a few months ago I was convinced they could, now… not so much. We need an explanation for the glaciations ending is the problem, if we haven’t got that we haven’t got much.

  130. Wondering Aloud says:

    The problem is the relationship that is “more powerful than alln the others” is also clearly dead wrong from the vary data set he is pointing at.

    Claiming minor problems with what someone else says does not alter this HUGE deliberate falsehood.

    Why are paleo proxies OK for the AGW folks to abuse but not ok when the evidence in them disputes it?

  131. Simon Evans says:

    Thank you.

  132. Nick Stokes says:

    Mark,
    I’ve been reluctant to get into this juvenile casting of aspersions on knowledge and qualification (particularly inappropriate here) but it’s hard to avoid. Your original disparagement of Simon was contradicted by explicit quotes from Wikipedia. And this is standard undergrad stuff where Wiki errors won’t last long. You keep bizarrely misquoting me – I still don’t get the negative chiding, and I didn’t say frequency doesn’t matter.

    Then you come up with something like this: gain is 1/(1-|a|). That just shows complete lack of understanding. The sign (pos or neg) of the feedback is the sign of a. This expression says that the gain is the same whether a is pos or neg. That may be in line with your original assertion, but it’s absurd. It says that feedback always increases gain.

    ps I don’t have a problem with your use of a discrete example.

  133. thefordprefect says:

    Jeff Alberts (09:49:16) :
    Are there ice core plots of Methane and temp?

    My post above – thefordprefect (17:22:56) – contains links to plots of most ice age entries/exits with ch4 and co2 levels fom epica ice cores. The same core data has dust values which will also affect ice age. These are available but not plotted above.
    Mike

  134. Chris V. says:

    CO2 levels in the upper atmosphere are about 320 ppm up to 90 km:

    http://www.agu.org/pubs/crossref/1992/92JD01622.shtml

    Water vapor decreases very rapidly with altitude. At 16 km, water vapor concentrations are only 1-2% of their surface concentrations. :

    http://www.aero.org/publications/crosslink/summer2000/02.html

    WRT to your second point, most of the energy hitting the earth from the sun is not in the infrared; most of the energy radiating from the earth is.

  135. Chris V. says:

    I understand the greenhouse effect, thank you. I didn’t imply that LW radiation is “trapped” at a certain level. My point is that all the LW leaving the earth has to go through the upper atmosphere to get out, but up there there is very little water vapor, so the CO2 absorption bands at high altitude are less saturated than they are at low altitudes.

  136. Joel Shore says:

    Steve’s thesis as you have stated it has been the accepted science for at least 30 years, so that’s hardly new news.

    And, what one can do is use the glacial – interglacial cycles to estimate the climate sensitivity, i.e., the global temperature response to a given change in forcings. And, what one finds if one adds up all of the forcings and compares it to the estimated temperature change, then one gets a result of 3/4 +-1/4 C / (W/m^2). [FYI, this calculation also tells us that about 1/3 of the temperature change between the glacial and interglacial cycles is due to changes in CO2 levels...with maybe another 10% due to the other greenhouse gases and most of the result due to the change in albedo due to changes in ice sheets and vegetation.]

    Since doubling CO2 creates ~4 W/m^2 of forcing, that corresponds to a climate sensitivity of between 2 and 4 C for a doubling of CO2.

    And, as Hansen has pointed out, this calculation counts albedo changes due to ice sheet expansion or contraction as a forcing, not a feedback. In our current “experiment” where we are increasing CO2, these will act as a feedback, which will tend to further increase the climate sensitivity…although there is some debate about how much and how quickly these feedbacks will act.

  137. The earth’s albedo was very high due to extensive ice cover which had much of North America and Europe buried in ice. Using the popular “CO2 and feedbacks explain everything”

    It is an all too prevalent misconception that albedo alone will effect the temperature of a radiantly heated ball . I recently implemented the basic Stefan-Boltzmann equation for gray balls and only differences in albedo towards and away from sources of heat make any difference . See http://cosy.com/Science/TemperatureOfGrayBalls.htm .

  138. Joel Shore says:

    Bob,

    I think that the source of your confusion is that you are assuming that the same emissivity should be used for both absorption and emission. However, these occur at very different wavelengths (i.e., the solar radiation is strongly weighted in the visible and near ultraviolet and infrared whereas the earth’s emission is in the far infrared) and hence that is not the case.

    As a general hint, if you find yourself in disagreement with well-settled science, rather than immediately questioning the science you should first question your own understanding.

  139. Sandw15 says:

    Joel Shore
    “Since doubling CO2 creates ~4 W/m^2 of forcing, that corresponds to a climate sensitivity of between 2 and 4 C for a doubling of CO2.”

    and then there’s this
    http://www.john-daly.com/artifact.htm

    The conclusion of this research was
    “the absorption is 0.054 W/m2 – and not 4.3 W/m2.
    This is roughly 80 times less than IPCC’s radiative forcing.”

    I understand enough chemistry to understand that the bottom line is that the absorption spectrum of CO2 is already saturated. All radiation in these frequencies is absorbed within 10 m of the Earth’s surface. No amount of CO2 can absorb frequencies that have already been extinguished. In other words, all the energy that CO2 can possibly absorb is already being absorbed.

    “And, as Hansen has pointed out, this calculation counts albedo changes due to ice sheet expansion or contraction as a forcing, not a feedback.”

    Seriously, I don’t understand…does that mean it counts more than it would as a feedback?…less?….the same? Is it counted in the 4.3 w/m2?
    It looks as if that 4.3w/m2 needs a little propping up or something. Maybe some Red Bull.

  140. thefordprefect says:

    @Steven Goddard
    I have now checked EPICA Vostok and Fuji data. All seem to show that exit from low temp period is co-incident with CO2 increase.

    EPICA and Vostok also have dust data. In general the increases in temperature are at a similar time to reduction in dust. However, CO2 increase is better synchronised to temp increase.

    You claim that there is no synchronicity between CO2 and Temperature. So I was wondering if you are using the same data as me. Could you give a link to the data you are using please?

    Have you checked the plots I made (see post above – thefordprefect (17:22:56) ) from data at this location http://www.ncdc.noaa.gov/paleo/icecore/antarctica/domec/domec_epica_data.html
    EPICA Dome C Ice Core Data is more detailed and longer than the Vostok data that I could find. Would you agree that CO2 seems to drive the exit from a cold period?
    Mike

  141. Sandw15 says:

    “Are there ice core plots of Methane and temp?”
    Try
    http://www.exploratorium.edu/climate/cryosphere/data2.html
    If memory serves, methane responds more quickly to the temperature change than CO2 but also lags the temp.

  142. Nick Stokes says:

    Mike,
    As I said above, there’s fairly widespread agreement now that CO2 does not look like an Ice Age initiator, partly because of its lagging phase. It was never part of the AGW argument that CO2 would be responsible, although since the cause of Ice Ages has not been clear, people have looked at it. Sec 2.4.1 of the AR3 2001 summarises the evidence at that time – there is more now. They say, for example:

    From a detailed study of the last three glacial terminations in the Vostok ice core, Fischer et al. (1999) conclude that CO2 increases started 600 ± 400 years after the Antarctic warming.

  143. Steven Goddard says:

    Prefect,

    I said nothing of the sort. What I said is that there is no correlation between CO2 levels and the direction which the temperature is moving. It is trivial to prove this. Pick any CO2 level on the ice core graph and count how many times that level correlated to downwards and upwards movements in temperature. You will find that the two quantities are equal, meaning there is 0% correlation between CO2 level and the temperature trend.

    If you are going to comment, please take the time to read what I said more carefully.

  144. thefordprefect says:

    Steven Goddard (21:15:12) :
    Apologies for not understanding you report.

    But now you have really confused me with your statement above.

    1). Do you mean that if you chose a CO2 level that occurs when the temperature is changing there are as many positive temperature transitions as negativ? – But surely mathematically there must always be as many positive transitions as negative?

    2). Or do you mean that if CO2 is increasing and is at a particular % it is as likely to be cooling as warming?

    3). Or do you mean that when CO2 is –
    above x% it is as often cold as hot
    below x% it is as often hot as cold

    If you mean the latter I will have a look at my EPICA results tonight and see if there is a transition CO2 level at which cold is prevalent
    Mike

  145. Joel Shore says:

    Sandw15 says:

    and then there’s this
    http://www.john-daly.com/artifact.htm

    The conclusion of this research was
    “the absorption is 0.054 W/m2 – and not 4.3 W/m2.
    This is roughly 80 times less than IPCC’s radiative forcing.”

    All because you can find something on the internet doesn’t make it right. The objection about the CO2 bands already being saturated is discussed here in the historical context: http://www.aip.org/history/climate/co2.htm (search on saturated). The fact that the forcing is around 4 W/m^2 is so universally agreed to be scientists, even skeptics like Richard Lindzen and Roy Spencer that it is way out in the weeds to try to argue otherwise.

    Seriously, I don’t understand…does that mean it counts more than it would as a feedback?…less?….the same? Is it counted in the 4.3 w/m2?

    Think about it. The calculation that gets the climate sensitivity of ~3/4 C per (W/m^2) from the ice age – interglacial transition includes in the W/m^2 the forcing due to changes in ice sheets and the resulting albedo change. However, when we are talking about calculating the climate sensitivity to changes in CO2, that is the only forcing that we are including. So, changes in the albedo due to such land ice sheet changes will then produce additional “forcing” that we haven’t really counted because it is part of the feedback process. This will cause some additional temperature change.

  146. Steven Goddard says:

    Prefect,

    If the climate is cyclical, then there will be an equal number of rising and falling transitions. The claim from Hansen, Gore etc. is that the climate has reached a “tipping point” where it is moving exponentially upwards. Whether or not they are correct about the tipping point, the ice core data provides no evidence to support their claims – and Al Gore was grossly incorrect in his usage of the giant ice core plot in his movie.

    The point is that the ice core data is irrelevant to the argument. All that it shows is that CO2 follows temperature.

  147. nevket240 says:

    “Basically, warming will be slower than originally thought, but most of the ice sheets will still melt and the albedo feedback from the lack of ice will push us to +6.0C from a doubled CO2 within 1,500 years.”

    1500 years.??????? good grief!! this looks like a “get out”
    Look back 1500 years and see how far humanity has come technologically. Just look back 100 years !!

    The EcoDruids are in panic mode as shown by the Steig Affair
    and that noteworthy attempt to involve the last man standing in this sordid affair of AGW, Antartica.

    regards

  148. nevket240 says:

    “We look forward to Mr Goddard’s next post where, having single-handedly shown how the world’s assembled climate and coral experts are mistaken”

    Oh, really sir. Assembled where?? How many are feeding on the public teat?? How many are really Climate Scientists??
    or just politically appointed advocates who are not being held accountable?? Why are so many other Climate Specialists now forging a publicly visible rebuttal?? Do you regard political activists hijacking public policy through bad science to be a moral issue or a “feedback” of some sort.

    regards

  149. Katherine says:

    Looks like we’ll have to wait a little longer for global CO2 measurements. Apparently the launch of the Orbiting Carbon Observatory ran into some problems.

    NASA Climate Change Satellite Has Troubled Launch

  150. foinavon says:

    Sandw15 (19:06:53) :

    I understand enough chemistry to understand that the bottom line is that the absorption spectrum of CO2 is already saturated. All radiation in these frequencies is absorbed within 10 m of the Earth’s surface. No amount of CO2 can absorb frequencies that have already been extinguished. In other words, all the energy that CO2 can possibly absorb is already being absorbed.

    No, that’s incorrect:

    If one considers longwave IR emitted from the Earth’s surface, the wavelength/energy of the emitted wavelength has to be considered, since the absorption coefficient (k) is inversely related to the wavelength of the absorption band. The transmisivity, t, (absorbtivity = 1-transmisivity) of a column of air is given by:

    t = e^(-k*p*l)

    where k is the absorption coefficient, p is the partial pressure and l is the path length.

    since the absorption coefficients for the absorption bands of the greenhouse gases are known[***], we can calculate the pathlength required to effectively absorb all of the radiation at that energy/wavelength.

    For 99% absorption, the pathlength of the 4-5 micron absorption band of CO2 is 625 metres at current atmospheric CO2 concentrations

    and for the ~14-20 micron absorption band, CO2 at 385 ppm is still unsaturated at 7,800 metres of altitude.

    likewise for the 12-20 micron infrared absorption band of water at 0.4%, water vapour is still absorbing at 1,700 metres.

    So the radiation is certainly not absorbed within 10 metres of the Earth’s surface!

    (iii) Thus, at current atmospheric greenhouse gas concentrations, the absorption bands aren’t saturated; enhancement of the concentration of greenhouse gases, particularly at higher altitudes [see (iv)], is effective in trapping more of the longwave IR emitted from the Earth’s surface.

    (iv) In any case, the altitude of absorption of IR emitted from the Earth’s surface isn’t that important. A key element of the greenhouse effect is the altitude of emission of longwave IR into space. This has to happen for radiative balance between incoming radiation and outward radiation.

    As greenhouse gases are added to the Earth’s atmosphere, the radiation of IR into space is suppressed at any altitude (especially altitudes far from the Earth’s surface). So the radiation emitted to space from (say) 5 km is suppressed by enhanced CO2 concentrations, and so the altitude of mean radiation to space is increased. Since an increased altitude in the troposphere is at a lower temperature, the efficiency of radiation to space is decreased. The troposphere must warm in order to restore radiative balance. Since the surface and troposphere are strongly coupled, the warming of the troposphere is transmitted to the earth’s surface (and vice versa).

    [***] This has been well known for more than half a century. See for example:

    RM Goody and GD Robinson (1951) Quart. J. Roy. Meteor. Soc. 77, 151-185

  151. foinavon says:

    Steven Goddard (06:24:14) :

    If the climate is cyclical, then there will be an equal number of rising and falling transitions. The claim from Hansen, Gore etc. is that the climate has reached a “tipping point” where it is moving exponentially upwards. Whether or not they are correct about the tipping point, the ice core data provides no evidence to support their claims – and Al Gore was grossly incorrect in his usage of the giant ice core plot in his movie.

    The point is that the ice core data is irrelevant to the argument. All that it shows is that CO2 follows temperature.

    Hansen doesn’t say that the “climate has reached a “tipping point” where it is moving exponentially upwards” (what is “it” btw, that is “moving exponentially upwards”?). Hansen iseems to be pretty explicit about what he says. He considers that the Earth can’t support a significant Greenland ice sheet at CO2 levels above 450/500 ppm at equilibrium (likely to be achieved on the millenial timescale). He considers that the climate sensitivity is likely to be a good bit higher than 3 oC, once the extremely long time scale ice dynamics are factored into the analysis. In another context he considers that burning all of the fossil fuels would result in truly catastrophic consequences and these might well involve non-linear effects that could be considered “tipping points” (e.g. massive die-off of tropical rainforests; massive release of methane from deep-sea clathrates as oceans warm…that sort of thing).

    We may as well address his views in the context of what he actually says/writes!

    And in fact the ice core data is highly relevant to the argument. One can’t inspect the ice core data visually and infer lack of effects of greenhouse gas levels from an absence of obvious visually-apparent signatures. One of the facts of life of modern science (since the mid 19th century at least) is that we can address phenomena that aren’t revealed by simplistic visual inspection. The ice age cycles have to be addressed in terms of a full consideration of the radiative forcings, feedbacks and amplifications. Everyone knows very well that changes in greenhouse gas levels don’t instigate transitions between glacial and interglacial periods. That’s the result of Milankovitch cycles. However the Milankovitch cycles produce puny changes in insolation and their effects can only produce the observed record once ice sheet dynamics and greenhouse gas forcings are included in the analysis. In terms of the record these contributors are pretty much “mixed together”. So while increases in atmospheric CO2 driven by Southern hemisphere sea ice retreat may lag the temperature rise recorded in Antarctic cores by 800 (+/- 600) years, that doesn’t mean that rising CO2 levels don’t contribute to the subsequent 4000-ish years of warming through a glacial-interglacial transition….and vice versa in a cooling transition.

    If one wants to understand these phenomena, all of the evidence needs to be considered. It’s helpful to know, for example, that while temperature changes precede CO2 changes in Antarctic cores, the rise in atmospheric CO2 levels occurs in advance of warming in the tropics (probably) and in the high Northern latitudes (very likely).

    http://icebubbles.ucsd.edu/Publications/CaillonTermIII.pdf

    (and subsequent work has reinforced that conclusion)

    http://www.sciencemag.org/cgi/content/abstract/1143791

  152. thefordprefect says:

    Steven Goddard (06:24:14) :
    If the climate is cyclical, then there will be an equal number of rising and falling transitions.

    Surely this depends on your stating and finishing times?

    … the ice core data provides no evidence to support their claims – and Al Gore was grossly incorrect in his usage of the giant ice core plot in his movie.

    Cannot comment on this as I have not watched the film, sorry.

    The point is that the ice core data is irrelevant to the argument. All that it shows is that CO2 follows temperature.

    but this is just not true. If you look at the EPICA core data then CO2 levels rise just at the point where the temperature begins to rise from the lows. The point at which temperatures start falling is more messy but CH4 and/or CO2 frequently begin to fall at that time. Dust during low temperature periods is often elevated.

    If you would have a look at the EPICA data I think you should agree that CO2 rise and temp rise ar synchronised.
    Mike

  153. thefordprefect says:

    As Foinavon has pointed out:
    The ice age cycles have to be addressed in terms of a full consideration of the radiative forcings, feedbacks and amplifications.

    Dust/CO2/CH4/clathrates/O3/H2O/NO2/Insolation/ etc/etc need to be looked at to fully explain ice age cycles. But from looking at EPICA data CO2 could be one reason for the exit from an ice age.

    One need also to understand that the ice core data is a very coarse set of data with most records being separated by 1-10,000 years. Not good for deciding which came first – heat or CO2
    Mike

  154. maksimovich says:

    Eight glacial cycles from an Antarctic ice core

    The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long—28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.

    http://www.nature.com/nature/journal/v429/n6992/abs/nature02599.html

  155. Wondering Aloud says:

    Your position on this thread has been that CO2 does not trail temperature change but in fact leads it. I don’t know if this data you refer is typical, representative, or cherry picked. What I do know from digging through these graphs is it doesn’t seem to support your contention. Some are unclear but others clearly show the temperature change leading the so called greenhouse gas increases though there seems to be an attempt through scaling to hide this.

    Perhaps there is some major change in dating methodology that may still turn this relation right side up for you, I certainly hope so, I am freezing my backside off. This data however doesn’t seem to do it.

  156. Wondering Aloud says:

    Chris V this is a reference to an abstract that just says it is a new method and doesn’t give us the actual method or data summary.

    I would think a method that claimed uniform levels up to 90 km is a method I’d like to see in detail before bought that. Darn unlikely is the first thought that leaps to mind.

  157. thefordprefect says:

    Wondering Aloud (15:47:06) : I assume you are refering to the plots in my post:
    thefordprefect (17:22:56).

    The data is not cherry picked – it is the data from EPICA ice core from the reference given

    Scaling is changed to get a suitable period on the plot nothing more.

    I have requested the original author look at this ice core data as it is longer and more detailed than the Vostok core. I would have expected him to download and plot the data himself rather than relying on my plots. If you disbelieve mine then it is a simple matter to replicate the plots yourself.
    Anyway, in all but one the plots (which include all the ends of cold periods in 800000 years as far as I am aware) CO2 is in sync with the rise in temp.
    The exception is at 722000 years bp in plot
    http://img27.imageshack.us/img27/634/iceageco2ch4650740et7.jpg

    Allowing for the granularity of the data (as much as 2000 years between points) I would suggest the temp and CO2 are increasing in synchronism. (remember that the graphs have their time scales reversed – earlier is to the right of the plot – scale is years before present [1950])

    I am not suggesting that CO2 or CH4 are the only forcings in operation but CO2 is certainly one of them.
    Mike

Comments are closed.