I recall a conversation I had with Dr. Bob Carter at a restaurant in Townsville, QLD after our public presentations there in June 2010 where he lamented the fact that many of the AGW proponents and many of his critics, “really don’t integrate the earth’s geologic timeline into their critical thinking”. I’ve had dozens of similar comments posted on WUWT. It only takes one look at this graph from Lorraine Lisiecki’s most recent paper in Geophysical Research Letters to get a handle on the geologic timeline of CO2 in recent Earth history. The title and x axis annotations are mine. Compare the peaks of CO2 and Sea Surface Temperature change over the last 1.5 million years.
Figure 3. Proxy comparison. (top) pCO2 (red) [Petit et al., 1999; Monnin et al., 2001; Siegenthaler et al., 2005; Lüthi et al., 2008 , Dd13CP−NA 2 (blue), alkenone concentration (green dashed) [Martínez‐Garcia et al., 2009″], boron‐based estimates with error bars (black dots [Hönisch et al., 2009]; gray circles [Tripati et al., 2009]; triangles [Seki et al., 2010]), and alkenone d13C estimates (squares) [Seki et al., 2010]. Dd13CP−NA 2 and alkenone proxies are scaled to ppm using the mean and standard deviation of pCO2 from 800–0 ka. (See auxiliary material for ODP 1090 age model.) (bottom) Changes in Dd13CP−NA 2 (blue), WEP SST [Medina‐Elizalde and Lea, 2005], and a tropical SST stack (purple) [Herbert et al., 2010] with trend reduced by 0.29°C/Myr to match the WEP. Dd13CP−NA 2 is scaled to °C using the standard deviation of the SST stack from 500–100 ka. – click for larger image”]
Granted, there’s not enough resolution on this graph to see the present (at far left) clearly, and I’m sure there will be arguments complaining it doesn’t show the current measured CO2 ppm value, at ~390ppm, but I’m not posting this to try to dispel current measurements, only to help others gain an understanding of the longer geologic record. Here’s the abstract and conclusion, along with another graph of interest:
Abstract: (emphasis mine)
A high‐resolution marine proxy for atmospheric pCO2 is needed to clarify the phase lag between pCO2 and marine climate proxies and to provide a record of orbital‐scale
pCO2 variations before the oldest ice core measurement at 800 ka. Benthic d13C data should record deep ocean carbon storage and, thus, atmospheric pCO2. This study finds that a modified d13C gradient between the deep Pacific and intermediate North Atlantic (Dd13CP−NA2) correlates well with pCO2. Dd13CP−NA 2 reproduces characteristic differences between pCO2 and ice volume during Late Pleistocene glaciations and indicates that pCO2 usually leads terminations by 0.2–3.7 kyr but lags by 3–10 kyr during two “failed” terminations at 535 and 745 ka. Dd13CP−NA 2 gradually transitions from 41‐ to 100‐kyr cyclicity from 1.3–0.7 Ma but has no secular trend in mean or amplitude since 1.5 Ma. The minimum pCO2 of the last 1.5 Myr is estimated to be 155 ppm at ∼920 ka. Citation: Lisiecki, L. E. (2010), A benthic d13C based proxy for atmospheric pCO2 over the last 1.5 Myr, Geophys. Res. Lett., 37, L21708, doi:10.1029/2010GL045109.
That minimum pCO2 920,000 years ago of 155ppm comes dangerously close to the value at which photosynthetic function shuts down, said to be around 140-150ppm. Earth came close to losing its plant life then.
Here’s another graph, again annotated by me, showing her data:
Figure 2. Comparison of pCO2 (gray) [Petit et al., 1999; Monnin et al., 2001; Siegenthaler et al., 2005; Lüthi et al., 2008 with (top) benthic d18O (black) [Lisiecki and Raymo, 2005 and (bottom) Dd13CP−NA 2 (black). Glacial stages are labeled by MIS number. In Figure 2 (bottom), pCO2 has been smoothed with a 2‐kyr boxcar filter.
I also found this passage of interest:
An anomalous phase relationship between ice volume and pCO2 may explain why these two warming events [Termination 6 (535 ka) and MIS 18 (745 ka)] are weaker than most Late Pleistocene terminations. During both “failed” terminations, the initial d18O change is approximately half the amplitude of most Late Pleistocene terminations; d18O spends ∼20 kyr at intermediate values of 3.8–4.2‰ and then briefly returns to more glacial values before achieving full interglacial conditions ∼40 kyr after the initial warming. The Dd13CP−NA2 lag during these two failed terminations suggests that full deglaciation requires an early pCO2 response.
This is along the lines of Andrew Lacis CO2 knob idea, but it is clear that CO2 isn’t fully in control, but one of many control knobs for climate. There’s also some discussions about the role of polar ice in climate regulation:
The initial trigger for terminations and the mechanistic link between pCO2 and northern hemisphere ice volume remain controversial [e.g., Huybers, 2009; Denton et al., 2010]. Variability in the phase between d18O and Dd13CP−NA2 supports the hypothesis of Toggweiler [2008] that glacial changes in pCO2 are controlled by southern hemisphere processes only weakly linked to northern hemisphere insolation and ice volume. However, tighter coupling between the hemispheres appears to develop at ∼500 ka, as suggested by smaller phase differences between Dd13CP−NA 2 and d18O (Table S3), an increase in pCO2 amplitude, and the phase lock between Antarctic temperature and northern hemisphere insolation during the last five terminations [Kawamura et al., 2007].
Conclusions
[19] In conclusion, Dd13CP−NA2 correlates well with ice core pCO2 from 800–0 ka and reproduces many features of the pCO2 record. Comparison of Dd13CP−NA
2 and pCO2 suggests that marine and ice core age models [Lisiecki and Raymo,
2005; Parrenin et al., 2007; Loulergue et al., 2007] differ by ≤2.7 kyr at terminations. Within the marine sedimentary record Dd13CP−NA2 usually leads d18O by 0.2–3.7 kyr at terminations but lags by 3–10 kyr during “failed” terminations at 535 and 745 ka. Thus, an early pCO2 response appears necessary for complete deglaciation, and pCO2 appears less tightly coupled to northern hemisphere ice volume before 500 ka. [20] Several proxies that correlate with pCO2 (Dd13CP−NA2 , South Atlantic productivity [Martínez‐Garcia et al., 2009], and WEP SST [Medina‐Elizalde and Lea, 2005]) and a carbon
cycle box model [Köhler and Bintanja, 2008] suggest that glacial pCO2 minima do not decrease during the MPT. Moreover, the minimum pCO2 concentration of the last
1.5 Myr is estimated to occur at 920 ka. Dd13CP−NA2 gradually shifts from 41‐kyr cycles to 100‐kyr cycles from 1.3–0.7 Ma but shows no secular trend in mean or amplitude over the last 1.5 Myr, whereas tropical SST records suggest warmer glacial maxima before 1.3 Ma [Herbert et al., 2010]. This likely indicates that at least one of these proxies is affected by factors other than pCO2 before 1.3 Ma; thus, additional high resolution proxies are needed.
======================================================
The thing to bear in mind is that these are proxies, not empirical measurements, and there’s no error/uncertainty shown. Of course at the present, we have ~ 390ppm of CO2 in the atmosphere, and that is nothing I dispute, not does any other skeptic I know of. What is clear from this study though is that our current period of increased CO2 is riding on the back of natural variability of CO2 concentration, which has been observed to occur with regularity over the past 1.5 million years. Of course the question arises as to how much the present concentrations will affect our slide into the next glaciation, if at all. If we are lucky, our “geoengineering” of the planet with some extra CO2 may very well be a lucky break for humanity. Notice that those peaks in CO2 and SST, the most recent of which is the very brief period of the rise of man, are quite short compared with the much longer periods of cooler temperatures.
h/t to Dr. Leif Svalgaard, who has the full paper here
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Mike says:
In fact these theoretical physicists turned “climatologists” have shown a consistent inability to handle proxy data with the necessary large grain of salt.
Crispin in Washington DC says:
In fact, referring to that survey that AGW people often quote as if it were scientific evidence, the majority of geologists don’t even think that people are responsible for a “significant part” of the warming trend.
Finally note that during a glacial expansion the amount of water vapor in the air would decrees significantly causing co2 to have 3 times its normal effect according to everybody’s favorite site Wikipedia.
I have a problem with these types of graphs, or rather in the context they are presented.
First of all all cheers to the work done, but it still is only a smooth out average of proxy data from a local area. So for starters it can only say something about the local CO2 levels if, and only if, it has been interpreted correctly and the proxies are accurate and all that and the proper calculations are done properly and the algorithm’s used doesn’t include any bugs, et cetera.
What bugs me the most with these kind of graphs is that everything has changed and it keeps changing all the time.
We change the way we collect data, the way we store data, the way we treat data. We have changed the programming language used to implement the algorithms, we have changed the algorithms, we have changed the math, we have change our criteria for interpreting the data how we implement the data, how we treat the data and the results and how we treat and interpret the results, some even change the reference periods from time to time, et cetera. It’s all BS unless you use the same methods of collecting, storing, treating of the data through the same algorithm implement the exact same through the exact same interface on the same god damn hardware (and yes even different hardware gives different results in the minute form, the more accurate the hardware becomes the more obvious the difference.)
Rational Debate has just commented:
“That’s an easy one and we have had the technology for decades – nuclear. The biggest problem with nuclear by far has been interference by anti-nuclear factions, and various government regulations.”
Agreed, and the greens lead the pack.
Liquid-fluoride thorium is the answer, just as soon as governments start listening to scientists, rather than computer modellers, magicians, druids, spin doctors, astrologers, prophets of doom, anything green, other politicians, and STOP WASTING MONEY ON INEFFECTUAL, OVER-PRICED, SHORT-LIVED WINDMILLS!!!
JPeden says: “…And all in the face of the fact that Communism has never worked and is essentially a dead end kind of human and societal evolution = Slavery.”
A dead end, indeed: “According to R. J. Rummel’s article in the Encyclopedia of Genocide (1999) the top three most murderous regimes are: (1) the Union of Soviet Socialist Republics, 62 million deaths, 1917-’87; (2) People’s Republic of China, 35 million, 1949-’87; (3) Germany under the National Socialist German Workers’ Party, 21 million, 1933-’45.”
That’s 118,000,000 people who have fallen victim to the Socialist “Workers’ Paradise” hoax, so far. That’s twenty Holocausts, all in the name of Socialist “equality.” Relabeling it ‘green’ will never remove the murderous stench that accompanies it.
“Power tends to corrupt, and absolute power corrupts absolutely…” –John Emerich Edward Dalberg Acton
See: http://rexcurry.net/socialism.html
JPeden says:
Actually, that is not true. Communism has worked for some people. Most notably, those who were in charge and were nimble enough to avoid being purged at the whim of those above/around them.
jorgekafkazar comments:
“Even at 100% efficiency, solar cells are so far from economic practicality that they are a pipe dream except for a very few remote applications. Promoting solar cells as alternative energy is, well, lunacy.”
Agreed, again, as above for B****Y WINDMILLS!!!, with the codicil that not only are photovoltaic cells very expensive, and have a relatively short life (some 20-25yr at present), they also are made with some rare materials. China has made a small fortune.
re post by:
Proxy credibility is based, of course, on a number of different issues. In Mann’s case, there were major flaws found that really dragged the credibility of his proxy use into question.
As to vegetation surviving ice ages “quite well…” how are you defining ‘quite well?’ Its my understanding that during ice ages many plant species go extinct, biodiversity really drops, etc. During periods of warmth, biodiversity explodes. In other words, not a lot survives ices ages ‘quite well.’
walt man says:
November 13, 2010 at 12:22 pm
… we see that vegetation survived the ice ages quite well:
180ppm 20000 years ago
——————————
Here are three versions of the global vegetation map at the last glacial maximum and we see that vegetation did not do too well in the ice ages – mainly because CO2 and precipitation levels were lower – C4 bushes and trees need extra precipitation when CO2 levels are low because the stomata need to be open more, allowing greater water transpiration – C4 grasses do okay with low CO2 and low precipitation but there is a limit.
(All the charts are from the same person who is the leading expert on this but for whatever reason the color schemes are not chosen very well).
http://www.esd.ornl.gov/projects/qen/lastgla.gif
http://upload.wikimedia.org/wikipedia/commons/e/e4/Last_glacial_vegetation_map.png
http://stommel.tamu.edu/~baum/paleoveg/veg-adams-big.gif
Mike says:
November 13, 2010 at 10:04 am
“We”, Mike?
Have you done ANYTHING personally to support your recommendation?
Or are you going to continue to drive, which requires petroleum-based fuels, or use electricity that comes from a majority of carbon-fuel power plants?
How about the clothes you wear (many petrol-based), or the plastics that you use, or the house that was built from materials hauled in on rubber-tired trucks.
I could go on and on and on, but please, enlighten us with an answer regarding your personal sacrifices showing how you’re “leaving carbon in the ground”.
John from CA says: November 13, 2010 at 11:25 am
Are the daily CO2 readings and trends at Mauna Loa related to Industrialization, Urbanization, and environmental conditions in South America?
Hi John. The increase in CO2 concentration being measured a Mauna Loa is due to the net burning of fossil fuel (coal, oil, gas) across the entire planet, of which South America is a contributor. Historically North America has been the major player.
crosspatch says: November 13, 2010 at 12:01 pm
If Earth’s atmosphere was pure CO2 and no water…
You are describing Venus.
nc says: November 13, 2010 at 11:43 am
R.Gates how much of the present C02 levels are caused by man? Also how long does that C02 hang around?
The increase in CO2 from pre-industrial times is near 100% caused by man as confirmed by isotope studies. A pulse of CO2 in the atmosphere has an “effective residence time” on the order of 100s of years. The spread of estimates for this number is quite large. (The “residence time” of an individual CO2 molecule is much shorter – of the order of years – and the two are regularly confused.)
Richard Sharpe says: November 13, 2010 at 11:22 am
I my opinion, those who are most vocally calling for a return to pre-industrial usage of carbon-based fuels are those who are least likely to survive if we do so.
Indeed. I am in the “c”AGW camp, meaning I am applying +3C as climate sensitivity, extrapolating the results and not liking where the analysis takes us. It is well and good to say the earth has seen warmer temperatures and life flourished. It is another thing altogether to assess how our current agricultural and coastal city based +6 billion people lifestyle can adapt if such a change happens rapidly.
The flip side is Richard’s comment. Calls from the environmental movement for 50% reductions in fossil fuel use by 2030 etc are legion with absolutely no credible mechanism for how this is to be accomplished. Many (not all) strident opponents to fossil fuel use have not invested the time to work out where their bread comes from and how the internet is powered. I highly recommend Dr David Mackay’s “Sustainable Energy without the hot air” http://www.withouthotair.com/. Other commentators have also recommended this read. It provides a framework for understanding the magnitude of the problem and the necessary scale of any enterprise that could provide a solution.
jorgekafkazar says:
November 13, 2010 at 12:32 pm
Currently photovoltaics are 2-3 times the cost nuclear power. Natural gas is close to half the cost of nuclear.
The efficiency of photovoltaics is largely irrelevant as space to place them is not a limiting factor. The critical metric is cost per megawatt hour. Natural gas is about $70, coal about $90, nuclear/geothermal/biomass all near $120, wind is around $160, and pulling up in distant last place the current generation photovoltaics is around $300.
The thing of it is that photovoltaic cost per megawatt hour can come down a heck of a lot in a short period of time. So can biomass. The rest have much less room for improvement although latest generation experimental nuclear reactor designs might be competitive with natural gas but it takes decades to go from experiment to safe commercial reactors. Biomass and photovoltaic are the most promising near term alternatives – biomass to generate liquid fuels to power the vast infrastructure extant in internal and external combustion motors and photovoltaics to power everything else. In the meantime there appears to be adequate supplies of existing energy sources and no need to waste money developing and/or installing alternatives that are far more expensive and show little promise of great cost/performance improvements. That money would be much better spent on R&D in PV and biomass improvements.
“John from CA says:
November 13, 2010 at 10:48 am
Given that temperature drives CO2 and given the observatory location related to ENSO changes, isn’t it a bit odd the CO2 record from 1958-present has nearly always risen?
John from CA says:
November 13, 2010 at 11:25 am
Are the daily CO2 readings and trends at Mauna Loa related to Industrialization, Urbanization, and environmental conditions in South America?”
Before 1750, temperatures drove CO2 levels since warm oceans can hold less CO2 (and all other gases) than colder oceans. However since the industrial revolution around 1750, man has been increasing the CO2 due to the burning of fossil fuels in houses and cars. The rate of man’s production of CO2 has really accelerated since 1945. As a result, the CO2 has increased from about 280 ppm in 1750 to 390 ppm today.
Roughly, about 50% of the CO2 man has put into the air since 1750 has stayed in the air, about 40% has gone into the oceans and about 10% has gone into increased photosynthesis in plants. The net effect is that concentrations in the air are now going up at a linear rate. See page 6 at (http://scienceandpublicpolicy.org/images/stories/papers/monckton/co2_report_july_2010.pdf). However the effect of CO2 on temperature is logarithmic (Law of diminishing returns). For a graphical illustration of this, see page 8 at (http://joannenova.com.au/globalwarming/the_skeptics_handbook_2-3_lq.pdf).
So the bottom line is that while this increased CO2 is good for plants and food production, it has virtually no further effect on temperature. Any talk about about tipping points and trying to avoid this with carbon capture is just not scientific and a total waste of money.
nc ask on November 13, 2010 at 11:43 am:
“R.Gates how much of the present C02 levels are caused by man? Also how long does that CO2 hang around?”
Ay, there’s the rub. The answer depends on who you ask and how you ask it. Do a Google search and you find very few answers that agree with one another. The IPCC put a value of 100 years on CO2 residence time in the atmosphere while many, perhaps most other scientific studies show a value of 5-15 years. Man’s contribution to CO2 levels is also hotly debated. AGW proponents say that half of all the human contribution accounts for all of the increase (and half is absorbed by oceans and plants.) But some estimates are as low as 15 ppmv; that’s roughly 4% of the CO2 in the atmosphere. (CO2 currently increases between one and 2.5 ppm annually.)
Yet a better question is “How much is mankind’s contribution to the ‘greenhouse effect?’ ” It is about 0.28%, if water vapor is taken into account– about 5.53%, if not. Yet another interesting question is to ask the difference between CO2 content of winds coming ashore on the Pacific coast and winds exiting the Atlantic coast of the USA. An article in Science magazine (sorry, I can’t find the reference now) said that North America was a net CO2 sink, probably due to reforestation. That makes one wonder why North America is accused of being the source of all this CO2, and what we can really do by way of Kyoto, et al.
As for the annual increase in CO2 in the atmosphere, that has been shown to vary by a factor of more than six within a six-year time period. (1992-1998). Something is not understood about sources and sinks. As a geologist, I would argue that the carbon cycle itself is poorly understood.
So it depends on what question you ask as well as of whom you ask it.
We were just talking about this in the post, ‘ “Extreme Global Warming” In The Ancient Past.’ As it is about to vanish from the bottom of “Recent Posts,” I hope I am forgiven for reprinting here what I replied there, about the subject. (The problem is that WUWT zooms through so many subjects, these days, that by the time I have finished mulling something over in my head and decided upon my reply, the post I want to reply about is already old news…”) Anyway, I replied:
RE: “The rapid increase in atmospheric carbon dioxide levels around 40 million years ago approximately coincides with the rise of the Himalayas and may be related to the disappearance of an ocean between India and Asia as a result of plate tectonics…”
The geology I’ve read suggests some sort of “hot spot” was able to melt away the “roots” of the Indian sub-continent, so that when it broke away from Antarctica it was able to zoom north at a speed something between twice and three times as fast as any continent “drifts” today.
Innocent Asia was just sitting there, minding its own business, with a vast continental shelf which had been accumulating coal and oil and gas for hundreds of millions of years, when along comes this upstart chip of Antarctica and smashes into it. It seems to me very little of the coal and oil and gas in Asia’s continental shelf survived the collision. (Unless there are reserves high up in the Himalayas.)
In other words, Mother Nature burned oil in a manner far more effective than mankind can, and leeched every bit of coal out, even from areas which would be completely inaccessible to man, and squeezed all the natural gas from the pre-collision continental shelf of Asia. One way or another, (and likely involving volcanoes and even limestone being turned to CO2,) a vast amount of “sequestered” CO2 was ejected back into the atmosphere.
If the uptick in CO2 caused warming, and if the warming didn’t “run away” then, why should warming “run away” now?
All that seemed to happen was the world became a warmer and lusher place, a place in many ways more kind to life, and to evolution. Mammals were able to thrive and develop all sorts of new species. The vast release of CO2 gave life a kick in the pants.
Were it not for the release of “sequestered” carbon, a planet might become increasingly cold and sterile, with plants gasping for breath due to so little CO2 being left in the air, and an “Iceball Earth” becoming a distinct possibility.
So…..perhaps those who like to think of Gia as having a mind that thinks, ought think in this manner:
Gia was very worried Earth might turn into an iceball, and all life would freeze. She had to figure out some way to release a lot of sequestered carbon, but there were no continents due to collide, and no asteroids available. Therefore, in a stroke of genius, She evolved humans out squeaky little tree shrews, and, at the last possible moment and in the nick of time, burned up lots of coal, and an ice age was averted.
At the very least, thinking in this manner would allow Moon-bats to feel much more warm and fuzzy about toasting their toes by a warm fire, and might even allow them to be thankful during a Thanksgiving dinner.
Rational Debate says:
November 13, 2010 at 1:35 pm
re post by:
walt man says: November 13, 2010 at 12:22 pm
Hmm! Proxy!
How come we can believe these proxies but not Mann’s?
Every one seems sure that CO2 at high levels will improve the earth an very low levels will kill vegetation. But, assuming the proxies are believable, then we see that vegetation survived the ice ages quite well: 180ppm 20000 years ago.”
The main problem, as I see it, is taking a proxy for say, temperature from tree ring formation, is that an increase in temperature will inevitably lead to an increase in atmospheric CO2. An increase in CO2 level will automatically increase plant growth, and so tree rings, as a proxy for temperature will, after several hundred years, be wider apart, due to abnormal growth. Which way is this taken in the production of all these graphs? Temperature rise always precedes atmospheric CO2 rise.
“Power tends to corrupt, and absolute power corrupts absolutely…” –John Emerich Edward Dalberg Acton
Hmph. This may appear as a truism, and no doubt we are all aware of its existence.
I would put it another way…
Corruption of power tends towards absolute power, and if conjoined can lead to absolute corruption.
Michael Chrichton in his book “State of Fear” gives a great synopsis of the vegetation rebound after the glaciers. He also provides references.
If one accepted for a moment that CO2 was driving temperature what would the graphs look like? The AGW theory states that the CO2 reduces the outgoing radiation
in the 14-18 micron band and so the earth has to increase its temperature in order to radiate more energy at the other wavelengths to compensate. However the earth’s climate system has a huge thermal inertia due to the capacitance of the sea so it would take many thousands of years for the effect of increased CO2 to be fully balanced. Thus one would expect that peak CO2 would correlate with the fastest rate of increase in temperature. That rate of rise would then gradually diminish as the absolute temperature increased until equilibrium was reached. Therefore the peak temperature should follow the peak CO2 by several thousand years. One would definitely not expect to see the temperature fall at a time when CO2 was at its peak. However it is generally understood that far from the absolute temperature lagging CO2 by several thousand years the CO2 tends to lag the temperature by up to one thousand years. Thus we find that periods of cooling tend to coincide with peak CO2 and periods of warming coincide with minimum CO2. Thus the facts do not support the theory.
The other thing that no one has been able to explain to me is why there should be a variation of CO2 linked to the Milankovitch cycles that drives the temperature. All logic seems to suggest that it is the temperature that is cyclic and that drives the CO2 due to it solubility in water being temperature dependent.
Indeed I believe AGW climate scientists accept that it is this way round but they then insist that the CO2 effect acts as a positive feedback. However the graphs shown have none of the characteristics of any positive feedback like overshoot. If there is any positive feedback it must be tiny compared with the main cyclical driver otherwise the oscillation would stop.
It was this contradictory paleo data that first made me question AGW orthodoxy. I have seen nothing that makes me change my view.
That minimum pCO2 920,000 years ago of 155ppm comes dangerously close to the value at which photosynthetic function shuts down, said to be around 140-150ppm. Earth came close to losing its plant life then.
Bill Illis says:
November 13, 2010 at 10:50 am
CO2 at 155 ppm was low enough that the most common C3 bushes and trees would have a very hard time growing. The globe was probably nearly completely C4 grass-covered with sparse forests in the high precipitation rain-forest areas only. [That should also say something about what the animals were eating at the time as well].
An interesting and even alarming aspect of this paper is the CO2 minima that have apparently come close to levels that restrict plant metabolism and photosynthesis. Puts in perspective the EPA’s intellectual brilliance in declaring CO2 a pollutant.
Here is a speculative hypothesis – probably wrong but perhaps thought-provoking.
Why does global temp spike up sharply after long gradual decline during recent glaciations? Lets assume that global temperature and climate are closely associated with and controlled by the hydrological precipitation cycle on land. Assume secondly that plant life – trees and land plants in particular – play a major role in sustaining the hydrological cycle in its current form (thus the big temp drop in the phanerozoic following evolution of land plants and trees.)
So (here’s the hypothesis): during glaciations, CO2 falls along with temperature. Eventually CO2 gets to a level when it starts to restrict plant metabolism. This causes a big change in global plant cover (land and sea), affecting hydrology. The effect on hydrology in turn affects climate – a big decrease in albedo for instance.
Thus the sharp termination of glaciations is due to a global plant stress event caused by incipient CO2 starvation. The end. Discuss.
Finally – as I have posted before – fig. 6 of this paper by Franck shows that it is CO2 starvation that will bring about the end of all life on earth:
http://www.biogeosciences.net/3/85/2006/bg-3-85-2006.pdf
Anyone know where I can get a good deal on an SUV?
Reply to DCC says:
November 13, 2010 at 3:05 pm
You mention a more than 6 fold change from 1992 to 1998. The low number for 1992, 0.43, just happens to be when the effects of the eruption of Mount Pinatubo were being felt. The Hadcrut3 anomaly for that year was 0.062. On the other hand, the high number of 2.93 was in 1998 when Hadcrut3 recorded its all time high anomaly (so far) of 0.548. See (http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3gl.txt). I am well aware of the often mentioned 800 year period between changes in prehistoric times, however it seems that these numbers cannot be a coincidence either. My explanation for both numbers being low in 1992 and both being high in 1998 is that while man was contributing about the same amount of CO2 in each of these years, the colder ocean in 1992 absorbed more CO2 and in 1998, the warmer ocean absorbed much less of the man-made CO2.
I feel that the following sentence needs some clarification: “But some estimates are as low as 15 ppmv; that’s roughly 4% of the CO2 in the atmosphere.” This certainly sounds much less than the 39% increase one obtains when comparing the 280 ppm from 1750 to 390 ppm today. They seem contradictory, but the 4% is just the excess humans contribute each year at the present time. In the 1800s, this percentage would have been much lower. However the cumulative total of all human increases over 260 years is that we have increased the CO2 by 39%. Do you more or less agree with this?
Clean up on isle 5
Ammonite says:
November 13, 2010 at 2:08 pm
Ammonite says:
November 13, 2010 at 2:11 pm
Ammonite says:
November 13, 2010 at 2:17 pm
Ammonite says:
November 13, 2010 at 2:35 pm
Don’t know bout you guys but I would prefer +3degC over today’s temps vs. -6degC. Gonna get very crowded down south during the next glacial.