I received this presentation of the “Bjerknes Lecture” that Dr. James Hansen gave at the annual meeting of the American Geophysical Union on December 17th. There are the usual things one might expect in the presentation, such as this slide which shows 2008 on the left with the anomalously warm Siberia and the Antarctic peninsula:
Source: James Hansen, GISS
Off topic but relevant, NASA has recently “disappeared”updated this oft cited map showing warming on the Antarctic peninsula and cooling of the interior:
There is also some new information in Hansen’s presentation, including a claim about CO2 sensitivity and coal causing a “runaway greenhouse effect”.
Hansen makes a bold statement that he has empirically derived CO2 sensitivity of our global climate system. I had to chuckle though, about the claim “Paleo yields precise result”. Apparently Jim hasn’t quite got the message yet that Michael Mann’s paleo results are, well, dubious, or that trees are better indicators of precipitation than temperature.
In fact in the later slide text he claims he’s “nailed” it:
He adds some caveats for the 2xCO2 claim:
Notes:
(1)
It is unwise to attempt to treat glacial-interglacial aerosol changes as a specified boundary condition (as per Hansen et al. 1984), because aerosols are inhomogeneously distributed, and their forcing depends strongly on aerosol altitude and aerosol absorbtivity, all poorly known. But why even attempt that? Human-made aerosol changes are a forcing, but aerosol changes in response to climate change are a fast feedback.
(2)
The accuracy of our knowledge of climate sensitivity is set by our best source of information, not by bad sources. Estimates of climate sensitivity based on the last 100 years of climate change are practically worthless, because we do not know the net climate forcing. Also, transient change is much less sensitive than the equilibrium response and the transient response is affected by uncertainty in ocean mixing.
(3)
Although, in general, climate sensitivity is a function of the climate state, the fast feedback sensitivity is just as great going toward warmer climate as it is going toward colder climate. Slow feedbacks (ice sheet changes, greenhouse gas changes) are more sensitive to the climate state.
Hansen is also talking about the “runaway” greenhouse effect, citing that old standby Venus in part of his presentation. He claims that coal and tar sands will be our undoing:
Hansen writes:
In my opinion, if we burn all the coal, there is a good chance that we will initiate the runaway greenhouse effect. If we also burn the tar sands and tar shale (a.k.a. oil shale), I think it is a dead certainty.
That would be the ultimate Faustian bargain. Mephistopheles would carry off shrieking not only the robber barons, but, unfortunately and permanently, all life on the planet.
I have to wonder though, if he really believes what he is saying. Perhaps he’s never seen this graph for CO2 from Bill Illis and the response it gives to IR radiation (and thus temperature) as it increases:
It’s commonly known that CO2’s radiative return response is logarithmic with increasing concentration, so I don’t understand how Hansen thinks that it will be the cause of a runaway effect. The physics dictate that the temperature response curve of the atmosphere will be getting flatter as CO2 increases. Earth has also had much higher concentrations of CO2 in past history, and we didn’t go into runaway then:
Late Carboniferous to Early Permian time (315 mya — 270 mya) is the only time period in the last 600 million years when both atmospheric CO2 and temperatures were as low as they are today (Quaternary Period ).
There’s lots more in this paper to behold in wonderment, and I haven’t the time today to comment on all of it, so I’ll just leave it up to the readers of this forum to bring out the relevant issues for discussion.
I’m sure Steve McIntyre at Climate Audit will have some comments on it, even though his name is not mentioned in the presentation. My name was mentioned several times though. 😉
paminator (00:17:45) :
correction- That should have been “Venus receives almost 2 times higher solar insolation due to its closer proximity to the sun”.
But it reflects ~75% of that insolation back into space so that its atmosphere actually receives less light from the sun than the Earth’s does.
Frank K.
December 22, 2008 10:07 am
I read through Hansen’s presentation, and I don’t know whether to laugh or cry. He clearly has lost it, and crossed the divide from being a credible scientist to a political activist. What I find particularly disturbing is his defense of the vandalism perpetrated by the “Kingsworth 6”. In addition, he has in the recent years said some vile and repulsive statements in defense of his “climate tipping point” hysteria. The most egregious was this:
“In his recent testimony to the Iowa Utilities Board, Rev. James Hansen argued that the construction of a new coal-based power plant is equivalent to the holocaust. The trains that bring coal to the new power plant are nothing else than the death trains that were moving the Jews to extermination camps:
… If we cannot stop the building of more coal-fired power plants, those coal trains will be death trains – no less gruesome than if they were boxcars headed to crematoria, loaded with uncountable irreplaceable species …” http://motls.blogspot.com/2007/11/hansen-power-plants-extermination-camps.html
—
I, for one, can no longer accept anything Jim Hansen says as anything more than political propaganda.
Pamela Gray
December 22, 2008 10:13 am
Maybe it is because people are doing “out the backdoor” assessments of the validity of said global warming and are beginning to smell a contrived panic driven agenda.
In the western part of the US we have this: Record lows at both minimum and maximum combined with record snow falls/liquid precip. The humidity is high yet the air temps are freezing my little behind. Until this month, I always thought colder meant dryer. Nope. I forgot my 5th grade lesson on precipitation circulation. The current weather reminds me much more of that little chapter in 5th grade science books about on-shore flow and mountain precipitation. Simple little model. So simple that it should make the current AGW models, that apparently are too complicated for one chapter in a 5th grade science book, literally short circuit and blow fuses on the computers used for said climate models. http://www.weather.gov/climate/index.php?wfo=pdt
This site = sanity
DR
December 22, 2008 10:34 am
Joel Shore,
This is just more of the same from Hansen.
He claimed to have had the smoking gun in 2005, but as it turns out it was a blank.
foinavon
December 22, 2008 10:47 am
The Scotese “graph”
Nasif Nahle (07:13:30)
anna v (07:19:27)
tty (08:03:04)
J Peden (08:19:15)
The Scotese graph in the Introductory post should set the alarm bells ringing! Surely a “skeptic” should ask the question “where are the data?”
The main problem can be put in a nutshell: A true determination of the relationship between atmospheric CO2 concentrations and earth’s surface temperature can only be obtained from paleodata under those circumstances where contemporaneous paleoCO2 and paleotemp data are available”
What you can’t do is take a scattering of sparse data points (which we can’t see since they’re not represented on the childish sketch) and draw straight lines between these encompassing many 10’s of millions of years in some instances, and pretend that all the vast intervening periods are thus defined.
The other problem is that the CO2 data is from Berners GeoCarb model in which a broad brush representation of the major elements of the earths CO2 history are modeled. It’s not really a proxy CO2 measure..it’s more of a proxy-based broad reconstruction.
I have no idea where the sketched temperature data comes from. Does anybody know? It doesn’t seem to be described on Scotese’s site. In the context of Scotese’s rather nice site describing epochal climate histories, it’s perfectly satisfactory as a broadly educational sketchy indication of how things have changed in the past. But I’d be surprised if Scotese was thrilled at seeing his sketch used as historical temperature evolution to compare with modeled broad-brush CO2 evolution.
There is a whole load of data on contemporaneous proxy CO2 and proxy temperature measures. These have been compiled quite recently in a review by Dana Royer and covers the data up to around 2005:
D.L. Royer (2006) “CO2-forced climate thresholds during the Phanerozoic” Geochim. Cosmochim. Acta 70, 5665-5675.
since Royer’s review, quite a number of further studies have been done which continue to highlight a general link between atmospheric CO2 levels and earth’s temperature under conditions where contemporaneous proxy CO2 and proxy temp. relationships have been established:
R.E. Carne, J.M. Eiler, J. Veizer et al (2007) “Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era” Nature 449, 198-202
W. M. Kurschner et al (2008) “The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of the terrestrial ecosystem” Proc. Natl. Acad. Sci. USA 105, 499-453.
D. L. Royer (2008) “Linkages between CO2, climate, and evolution in deep time” Proc. Natl Acad. Sci. USA 105, 407-408
Zachos JC (2008) “An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics” Nature 451, 279-283.
Doney SC et al (2007) “Carbon and climate system coupling on timescales from the Precambrian to the Anthropocene” Ann. Rev. Environ. Resources 32, 31-66.
Horton DE et al (2007) “Orbital and CO2 forcing of late Paleozoic continental ice sheets” Geophys. Res. Lett. L19708 (Oct. 11 2007).
B. J. Fletcher et al. (2008) “Atmospheric carbon dioxide linked with Mesozoic and early Cenozoic climate change” Nature Geoscience 1, 43-48.
and modelling studies of glaciation thresholds for CO2:
DeConto RM et al (2008) Thresholds for Cenozoic bipolar glaciation Nature 455 652-655.
Lunt DJ et al (2008) Late Pliocene Greenland glaciation controlled by a decline in atmospheric CO2 levels. Nature 454, 1102-1104
etc…
Joel Shore
December 22, 2008 10:50 am
hunter says:
AGW beleivers, when it is convenient, claim climate reposnes to forcings is swift, but when the evidence that the Earth climate is not radically changing, they make the pitiful dodge that ‘we are not seeing the full effect yet’.
….
When Pinatubo or Krakatoa blew, the impact was immediate. If we were seeing someting anywhere close to what Hansen and the IPCC claim, it would alreadybe happening.
Since the same models that accurately represent the effect on climate of the Mt Pinatubo eruption are the ones that predict that it will take a fair bit of time to see the full effect of the current forcings, you are not correct. Now, you could try to make the argument that the effective relaxation times in the climate models are not realistic and the actual times are much shorter (as Schwartz did, although he has now had to backpedal quite a bit in the face of evidence that his method of determining the relaxation time systematically underestimates it in model systems where the correct answer is known). However, to claim that one cannot both account for the effect of Mt Pinatubo and have a reasonably long relaxation time for the climate system is demonstrably wrong.
I don’t consider 118 years (1890 – present) to be a small range? Actually it’s pretty much the entire range so it can’t be ’small’. Small would be 5-10 years, at least to me.
For an exponential or logarithmic function, the question of regarding the region of linearity is related to the FRACTIONAL change in the function over the time period in question. I don’t think you can determine anything one way or the other from your intuition on what is a short or long period of time.
I’d disagree that it is ‘not that big a difference’, close to a 20% difference is big (46% is ~ 20% larger than 37.5%).
Well, I won’t quibble with you on what constitutes a large or small difference but considering that you were originally claiming our current CO2 concentrations (being ~37.5% of the way between 280ppm and 560ppm on a linear scale) constituted being >70% the way to a doubling on a log scale, I would say that the fact that it actually is only 46% of the way to a doubling does mean that the linear-to-log conversion doesn’t make nearly the difference that you thought it did.
Assuming 3C for doubling and accepting the 46% figure, doesn’t that mean that we should have already seen a 1.15 – 1.61C temp increase (and we clearly haven’t seen even the low end of that range)…
See the rest of my post there. Given that we are out-of-equilibrium and given the large uncertainty in the value of the negative aerosol forcing, what we have seen is compatible with a very broad range of values for the equilibrium climate sensitivity. The simple fact is that the 20th and early 21st century temperature record just doesn’t provide us with very strong constraints on this value, which is why we have to look at other empirical evidence.
Uncle Larry
December 22, 2008 11:45 am
Considering the “man made” increase in carbon dioxide (from the burning of fossil fuels and tuna casseroles), shouldn’t we be seeing a corresponding 2-to-1 reduction in oxygen levels in respect to current carbon dioxide levels?
I’m at a loss to find any long-term data on the subject. Does anyone have any sources for such data?
Thanks,
-Uncle Larry
Solomon Green
December 22, 2008 11:51 am
I do not think that Ben Kellet needs ice-core evidence that the Northern Hemisphere has warmer than now during the last 1,000 years. Greenland (so called because of its fertility) was actively farmed from about the eighth century until the little ice-age in the fourteenth cetury. This is borne out not only by archeology but also by contemporaneous written documents. It is still not warm enough to support much farming now. So if the ice cores do not show this pattern of warmer climates one must question either the accuracy of the ice-cores samples or the science which translates ice core samples into historical temperatures.
AnonyMoose
December 22, 2008 11:59 am
“Thousands of scientists reviewed the reports and were able to make as many critiques as they wanted.”
Last time I checked, the critiques were locked up in IPCC headquarters and someone was having trouble getting permission to visit and view them. Anyone know of an independent examination of them?
apb
December 22, 2008 12:20 pm
I love the 600-million year graph showing declining CO2 levels vs. temperature – my question would be, why are there apparent flat limits to temperature at 22C and 12C ? Since we’re at the lower limit, isn’t there only 1 direction to go? Temperature changes certainly weren’t caused by humans before.
hernadi-key
December 22, 2008 12:39 pm
BREAKING NEWS..!!!
————————————————————————-
Did Early Global Warming Divert A New Glacial Age?
ScienceDaily (Dec. 18, 2008) — The common wisdom is that the invention of the steam engine and the advent of the coal-fueled industrial age marked the beginning of human influence on global climate.
But gathering physical evidence, backed by powerful simulations on the world’s most advanced computer climate models, is reshaping that view and lending strong support to the radical idea that human-induced climate change began not 200 years ago, but thousands of years ago with the onset of large-scale agriculture in Asia and extensive deforestation in Europe.
What’s more, according to the same computer simulations, the cumulative effect of thousands of years of human influence on climate is preventing the world from entering a new glacial age, altering a clockwork rhythm of periodic cooling of the planet that extends back more than a million years.
“This challenges the paradigm that things began changing with the Industrial Revolution,” says Stephen Vavrus, a climatologist at the University of Wisconsin-Madison’s Center for Climatic Research and the Nelson Institute for Environmental Studies. “If you think about even a small rate of increase over a long period of time, it becomes important.”
Addressing scientists on Dec 17 at a meeting of the American Geophysical Union, Vavrus and colleagues John Kutzbach and Gwenaëlle Philippon provided detailed evidence in support of a controversial idea first put forward by climatologist William F. Ruddiman of the University of Virginia. That idea, debated for the past several years by climate scientists, holds that the introduction of large-scale rice agriculture in Asia, coupled with extensive deforestation in Europe began to alter world climate by pumping significant amounts of greenhouse gases — methane from terraced rice paddies and carbon dioxide from burning forests — into the atmosphere. In turn, a warmer atmosphere heated the oceans making them much less efficient storehouses of carbon dioxide and reinforcing global warming.
That one-two punch, say Kutzbach and Vavrus, was enough to set human-induced climate change in motion.
“No one disputes the large rate of increase in greenhouse gases with the Industrial Revolution,” Kutzbach notes. “The large-scale burning of coal for industry has swamped everything else” in the record.
But looking farther back in time, using climatic archives such as 850,000-year-old ice core records from Antarctica, scientists are teasing out evidence of past greenhouse gases in the form of fossil air trapped in the ice. That ancient air, say Vavrus and Kutzbach, contains the unmistakable signature of increased levels of atmospheric methane and carbon dioxide beginning thousands of years before the industrial age.
“Between 5,000 and 8,000 years ago, both methane and carbon dioxide started an upward trend, unlike during previous interglacial periods,” explains Kutzbach. Indeed, Ruddiman has shown that during the latter stages of six previous interglacials, greenhouse gases trended downward, not upward. Thus, the accumulation of greenhouse gases over the past few thousands of years, the Wisconsin-Virginia team argue, is very likely forestalling the onset of a new glacial cycle, such as have occurred at regular 100,000-year intervals during the last million years. Each glacial period has been paced by regular and predictable changes in the orbit of the Earth known as Milankovitch cycles, a mechanism thought to kick start glacial cycles.
“We’re at a very favorable state right now for increased glaciation,” says Kutzbach. “Nature is favoring it at this time in orbital cycles, and if humans weren’t in the picture it would probably be happening today.”
Importantly, the new research underscores the key role of greenhouse gases in influencing Earth’s climate. Whereas decreasing greenhouse gases in the past helped initiate glaciations, the early agricultural and recent industrial increases in greenhouse gases may be forestalling them, say Kutzbach and Vavrus.
Using three different climate models and removing the amount of greenhouse gases humans have injected into the atmosphere during the past 5,000 to 8,000 years, Vavrus and Kutzbach observed more permanent snow and ice cover in regions of Canada, Siberia, Greenland and the Rocky Mountains, all known to be seed regions for glaciers from previous ice ages. Vavrus notes: “With every feedback we’ve included, it seems to support the hypothesis (of a forestalled ice age) even more. We keep getting the same answer.”
Uncle Larry “shouldn’t we be seeing a corresponding 2-to-1 reduction in oxygen levels ”
It really would be 8 to 3, as the real ratio is O2=32 and C=12
John S.
December 22, 2008 12:40 pm
The absence of any scientific rigor in Hansen’s immodest claims is patently evident from his miscasting of CO2 as a “forcing” and from his reliance upon an entirely novel notion of “positive feedback” by water vapor leading to a “runaway greehouse.”
CO2 produces not one calorie of energy; it merely absorbs and reradiates energy in a few narrow bands from a planetary surface thermalized entirely by insolation. It is thus a capacitance effect–a minor one, at that, compared to water vapor–and not any proper (i.e., energetic) forcing of the climate system.
Evaporation and moist convection combined rival radiation as a surface cooling mechanism, redistributing surface heat into the atmosphere. That heat is subsequently partially exchanged back and forth with the surface through radiative transfer. There can be no magic multiplication of total thermal energy through any proper feedback, however, in violation of conservation laws. The salutary effect of this so-called “greenhouse” is an elevated surface average along with a low-pass filtering of variations, which results in far smaller diurnal range than is oberved at the Moon. The harsh extermes found there are avoided.
At climatic time scales, the premise that increased CO2 concentrations lead to higher surface temperatures runs into a two-fold problem: temperature leads CO2 on millenial scales and the variables are virtually incoherent on multi-decadal basis. The weak millennial correlations are best expalined by outgassing from the oceans.
The basic physical fact seemingly ignored by Hansen is that one cannot obtain higher humidities aloft without an attendant increase in evaporative cooling at the surface and in cloudiness. The usual GCM model assumption of constant relative humidities is simply unrealistic, as is their parameterized treatment of “average” cloudiness. The danger we’re plainly witnessing is a runaway deification of results from unproven models.
anna v
December 22, 2008 12:45 pm
foinavon ,
from the link you provided about aerosols: Role of Black Carbon on Global and Regional Climate Change
V. Ramanathan http://oversight.house.gov/documents/20071018110734.pdf VI.Major Source of Uncertainty: Emission Sources for BC
Our ability to model the effects of BCs in climate models is severely limited. One of the
main reason is the large uncertainty (factor of 2 or more) in the current estimates of the
emission of the organic (OC) and elemental carbon (EC) (See Bond et al. 2004 and
2007).. Furthermore, biomass burning contribute significantly to the emissions of OC
and EC and the historical trends (during the last 100 years) in these emissions are
unknown and models currently resort to ad-hoc methods such as scaling the current day emissions with past trends in population.
So we are talking factors of two, now.
I suspect all the references you give ( which unfortunately we cannot read since we do not subscribe to the publications) buried somewhere will be similar hedgings.
Do not get me wrong. It is fine that people explore all possible avenues, publish and defend them. That is normal in a scientific environment.
What is wrong is saying the science is settled, which you have adopted and shout loudly. The science is NOT settled. And trying to stampede the world politicians into disastrous energy policies on such flimsy and precarious arguments is unethical and immoral and downright dangerous.
Maybe the gods will take pity on us an bring on a few more winters like this so that AGW hotheads cool off.
Steve
December 22, 2008 12:46 pm
Hey Foinavon,
Yeah, sorry, I did change the title accidentally (I had no ulterior motive other than being lazy 😉 ). I got it from this site without double checking properly and was in a rush.
It is:
Compo, G.P., and P.D. Sardeshmukh, 2008: Oceanic influences on recent continental warming. Climate Dynamics, doi: 10.1007/s00382-008-0448-9.
I’m pretty sure in that paper they don’t claim what the main cause of the oceans warming was (and that’s what I’m interested in) . They say it could be GHG but that it could also be due to natural causes and is a matter of active investigation. Sure GHG may have warmed the oceans but to what degree and were they the main driver of that warming. If so what evidence do we have to show that. Also, do we know what the thermal equilibrium time between atmosphere and ocean? Obviously that is vitally important in our understanding of climate sensitivity to CO2.
There was warming of the planet between say 1860 and 1940 and I find it hard to believe that that was due to CO2. If you look at the global mean surface temperature records, from 1860 to around 1915 the temperature goes up and then back down again even though there is very little change in CO2 (I think there might be a slight upwards trend in CO2). From 1860 to 1940 there is roughly a 0.5 degree change in temperature.
From the SIple Ice core I get the CO2 concentration in 1860 at around 289 ppm and in 1943 around 307 ppm. The global mean temperatures show a rise of around 0.5 degrees but by my calculations and your formula I get CO2 only being able to account for 0.26 of that or roughly half even assuming the oceans have come to thermal equilibrium and CO2 has done all its warming. If it hasn’t then the warming due to CO2 is less than 0.26.
Therefore, to me, there had to have been some natural (or other non CO2 forced) process at work and I’m still not convinced the IPCC (a Polemic of it’s own you’d have to admin) has enough evidence to claim that natural variation can’t have caused the warming of the latter 20th century. Claiming that increases in atmospheric CO2 was the main driver of temperature because you can’t think of any NV that could be responsible seems highly suspect to me because there have been these processes in the past, we may not know what they are and have fancy formulas for them but that doesn’t mean they don’t exist.
Using aerosols for canceling the warming reminds me of Ptolemy’s earth centric model of the solar system and the mini cycles mars and other planets took, they’re necessary to uphold ones view. Surely there is also another plausible explanation, that climate is not as sensitive to CO2 as assumed (2C02 = 3C). Is that not possible?
Chylek [2007] certainly seem to think it is. I think it would make more sense to me to assume that climate sensitivity is small until we are more sure of the effects of aerosols (i.e. uncertainties are reduced) and hence more certain of the climate sensitivity.
Surely you must agree statements like “the debate is over” and “science is settled” don’t help in these situations and seems to imply more certainty to Joe public like me than there really is. Then again I guess no one has actually defined what the “debate” was and which “science” has been settled.
Roy Sites
December 22, 2008 12:50 pm
If you assume that the temperature change is the result of CO2 and then compute the climate sensitivity to a doubling of CO2 and then using that result to prove the temperature change is the result of doubling the CO2 then this is circular reasoniong. I do not see how Mr. Hansen’s calculations are any more than circular reasoning. Please indicate where I am wrong.
Mark
December 22, 2008 12:52 pm
Speaking of Hansen, when I look at his graph (C) on the second page of the following link, I see a regularly occurring temperature cycle. http://www.giss.nasa.gov/meetings/arctic2007/pdf/aws_hansen.pdf
And when I look at where we are right now on the graph (time wise), the slope of those two (red and blue) curves preceding the temperature increases are very similar to the other 3 that happened in the past.
Unless I’m missing something, I see nothing abnormal in that graph for today’s time frame that hasn’t already occurred in the past 3 cycles.
Graeme Rodaughan
December 22, 2008 12:56 pm
sauerkraut (05:46:13) : Cannot help but wonder if some of you folks are related to the creationista/ID folks.
What do ya alls think of comparison of the atmosphere to blood – specifically its function as a buffer? As with blood, it absorbs and absorbs and absorbs until a critical point is reached, whereby it all goes downhill from there.
And your bland generalisation adds “what value” to the conversation?
Comparing the buffering properties of blood with the Atmosphere – have you heard the term “Drawing a long bow”.
My commiserations for your recent loss.
Mark (12:52:08) :
Speaking of Hansen, when I look at his graph (C) on the second page of the following link, I see a regularly occurring temperature cycle. http://www.giss.nasa.gov/meetings/arctic2007/pdf/aws_hansen.pdf
And when I look at where we are right now on the graph (time wise), the slope of those two (red and blue) curves preceding the temperature increases are very similar to the other 3 that happened in the past.
What you’re missing is the last 58 years of growth in CO2 (+~70ppm) and warming (~0.5ºC)!
foinavon
December 22, 2008 1:15 pm
anna v,
Yes there’s considerable uncertainty in the extent of the aerosol forcing. However the evidence indicates that it’s protecting us somewhat from the warming effects of hugely enhanced greenhouse gas concentrations. The nett aerosol contribution is a cooling one. As you have read in the paper that you’ve quoted from, Ramanathan is concerned about the possibility of removing the aerosol load since this will cause a significant enhancement of greenhouse warming (Ramanathan would like to find a means of selectively removing the warming contribution from black carbon).
I’m not shouting. I may have used the odd exclamation mark (!) but you’re the one using cpitalised bold text! As for “the science being settled”, one needs to be specific. Some science is essentially settled, some less so, and some is still controversial……that’s science for you!
It’s unfortunate that you don’t feel able to access the scientific literature (don’t you have a local University library?). It’s very easy to become mired in disinformation by resorting to blogs and other dodgy websites. If you use Google Scholar, you might be able to obtain downloadable versions of the papers. Or email the authors (email addresses obtainable with the free abstracts on journal websites. Some of the articles might be “Open Access”, and anything published by the major publicly funded research organisations (NASA Giss etc.) should be publically available free of charge.
I wouldn’t say that the papers I cited are “hedgings” at all. That’s rather presumptious! They present evidence that informs our understanding…
Just because the world is warming doesn’t mean that we don’t have winters. It’s quite a mild one over here in Blighty!
To: foinavon
“I’m not sure what you mean by “hot spot”. Can you enlighten us? It’s predicted that greenhouse warming will result in particularly strong warming in the high Northern latitudes due to efficient wind and ocean currents that transport excess heat from the equator, coupled with albedo feedbacks. is that what you mean?”
“anyway, please give us some clarification with respect to the “hot spot”
Let me try to fill the gap in your inconvenient memory loss. 😉
“Twelve IPCC climate model forecasts for the Fourth Assessment Report are shown at: http://ipccwg1.ucar.edu/wg1/Report/suppl/Ch10/Ch10_indiv-maps.html: see the column for Figure 10.7.
These model experiments follows the ‘A1B’ emissions scenario, a medium-range emissions trajectory out to 2100. The global average surface warming as of the end of the century for the GISS model is about 2.3 C.29. The tropospheric average is twice that, reaching 5 C, and the focal pattern emerges at the beginning of the forecast period. The visual pattern shown in Figure 5 is found in all 12 climate model simulations done for the recent IPCC report. In the Fourth Assessment Report Figure 9.1 (see http://ipccwg1.
ucar.edu/wg1/Report/AR4WG1_Pub_Ch09.pdf, page 675) a ‘hindcast’ is presented examining model-generated climate patterns for the interval 1890 to 1999. The Figure 5 pattern shows up in the greenhouse-only run (panel c) and, because the greenhouse forcing dominates the experiment,
in the summed changes (panel f). The clear implication of this graph is that a strong warming trend in the tropical troposphere ought to be underway already and should be the dominant pattern of change in comparison with all other forcings. The Figure 5 pattern is also shown in a model-generated ‘hindcast’ that simulates climatic changes from 1958 to 1999 under the assumption of strong GHG-warming, which was done for the US
Climate Change Science Program Report, Figure 1.3 Panels A and F, page 25, available at http://www.climatescience.gov/Library/sap/sap1-1/finalreport/default.htm. Again, the bright disc in the tropical troposphere is the dominant feature of the diagram.”
Now that you know what we are talking about, would you care to explain your view of the discrepancy?
More complete information here: http://www.friendsofscience.org/assets/files/documents/T3tax.VVedition.pdf
paminator
December 22, 2008 1:18 pm
Phil- you say “But it reflects ~75% of that insolation back into space so that its atmosphere actually receives less light from the sun than the Earth’s does.”
Indeed I did mention the difference in Albedo between Earth and Venus in my previous post-
“…but its Albedo is also higher than Earth (0.65 versus 0.3 for Earth).”
More accurate numbers-
Earth Albedo = 0.36, Venus = 0.65, Ratio V/E = 1.77
Top of atmosphere insolation Earth = 1367 W/m^2, Venus = 2600 W/m^2, Ratio = 1.9
Estimated surface insolation Earth = 1367*(1-0.36) = 875/m^2 at equator, noon sunward side
Venus = 2600*(1-0.65) = 910 W/m^2 at equator, noon on sunward side.
Pretty close to even by my estimates.
Surface temperature average Earth = 288 K, Venus = 737 K.
Biggest single difference between Venus and Earth- 92 times more total atmosphere on Venus (both atmospheres are good absorbers of infrared emission from the surface).
No runaway greenhouse needed.
Hansen is well aware of all of this, since I believe his PhD work involved modeling the atmosphere of Venus!
*sigh*
paminator (00:17:45) :
correction- That should have been “Venus receives almost 2 times higher solar insolation due to its closer proximity to the sun”.
But it reflects ~75% of that insolation back into space so that its atmosphere actually receives less light from the sun than the Earth’s does.
I read through Hansen’s presentation, and I don’t know whether to laugh or cry. He clearly has lost it, and crossed the divide from being a credible scientist to a political activist. What I find particularly disturbing is his defense of the vandalism perpetrated by the “Kingsworth 6”. In addition, he has in the recent years said some vile and repulsive statements in defense of his “climate tipping point” hysteria. The most egregious was this:
“In his recent testimony to the Iowa Utilities Board, Rev. James Hansen argued that the construction of a new coal-based power plant is equivalent to the holocaust. The trains that bring coal to the new power plant are nothing else than the death trains that were moving the Jews to extermination camps:
… If we cannot stop the building of more coal-fired power plants, those coal trains will be death trains – no less gruesome than if they were boxcars headed to crematoria, loaded with uncountable irreplaceable species …”
http://motls.blogspot.com/2007/11/hansen-power-plants-extermination-camps.html
—
I, for one, can no longer accept anything Jim Hansen says as anything more than political propaganda.
Maybe it is because people are doing “out the backdoor” assessments of the validity of said global warming and are beginning to smell a contrived panic driven agenda.
In the western part of the US we have this: Record lows at both minimum and maximum combined with record snow falls/liquid precip. The humidity is high yet the air temps are freezing my little behind. Until this month, I always thought colder meant dryer. Nope. I forgot my 5th grade lesson on precipitation circulation. The current weather reminds me much more of that little chapter in 5th grade science books about on-shore flow and mountain precipitation. Simple little model. So simple that it should make the current AGW models, that apparently are too complicated for one chapter in a 5th grade science book, literally short circuit and blow fuses on the computers used for said climate models.
http://www.weather.gov/climate/index.php?wfo=pdt
This site = sanity
Joel Shore,
This is just more of the same from Hansen.
He claimed to have had the smoking gun in 2005, but as it turns out it was a blank.
The Scotese “graph”
Nasif Nahle (07:13:30)
anna v (07:19:27)
tty (08:03:04)
J Peden (08:19:15)
The Scotese graph in the Introductory post should set the alarm bells ringing! Surely a “skeptic” should ask the question “where are the data?”
The main problem can be put in a nutshell:
A true determination of the relationship between atmospheric CO2 concentrations and earth’s surface temperature can only be obtained from paleodata under those circumstances where contemporaneous paleoCO2 and paleotemp data are available”
What you can’t do is take a scattering of sparse data points (which we can’t see since they’re not represented on the childish sketch) and draw straight lines between these encompassing many 10’s of millions of years in some instances, and pretend that all the vast intervening periods are thus defined.
The other problem is that the CO2 data is from Berners GeoCarb model in which a broad brush representation of the major elements of the earths CO2 history are modeled. It’s not really a proxy CO2 measure..it’s more of a proxy-based broad reconstruction.
I have no idea where the sketched temperature data comes from. Does anybody know? It doesn’t seem to be described on Scotese’s site. In the context of Scotese’s rather nice site describing epochal climate histories, it’s perfectly satisfactory as a broadly educational sketchy indication of how things have changed in the past. But I’d be surprised if Scotese was thrilled at seeing his sketch used as historical temperature evolution to compare with modeled broad-brush CO2 evolution.
There is a whole load of data on contemporaneous proxy CO2 and proxy temperature measures. These have been compiled quite recently in a review by Dana Royer and covers the data up to around 2005:
D.L. Royer (2006) “CO2-forced climate thresholds during the Phanerozoic” Geochim. Cosmochim. Acta 70, 5665-5675.
since Royer’s review, quite a number of further studies have been done which continue to highlight a general link between atmospheric CO2 levels and earth’s temperature under conditions where contemporaneous proxy CO2 and proxy temp. relationships have been established:
R.E. Carne, J.M. Eiler, J. Veizer et al (2007) “Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era” Nature 449, 198-202
W. M. Kurschner et al (2008) “The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of the terrestrial ecosystem” Proc. Natl. Acad. Sci. USA 105, 499-453.
D. L. Royer (2008) “Linkages between CO2, climate, and evolution in deep time” Proc. Natl Acad. Sci. USA 105, 407-408
Zachos JC (2008) “An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics” Nature 451, 279-283.
Doney SC et al (2007) “Carbon and climate system coupling on timescales from the Precambrian to the Anthropocene” Ann. Rev. Environ. Resources 32, 31-66.
Horton DE et al (2007) “Orbital and CO2 forcing of late Paleozoic continental ice sheets” Geophys. Res. Lett. L19708 (Oct. 11 2007).
B. J. Fletcher et al. (2008) “Atmospheric carbon dioxide linked with Mesozoic and early Cenozoic climate change” Nature Geoscience 1, 43-48.
and modelling studies of glaciation thresholds for CO2:
DeConto RM et al (2008) Thresholds for Cenozoic bipolar glaciation Nature 455 652-655.
Lunt DJ et al (2008) Late Pliocene Greenland glaciation controlled by a decline in atmospheric CO2 levels. Nature 454, 1102-1104
etc…
hunter says:
Since the same models that accurately represent the effect on climate of the Mt Pinatubo eruption are the ones that predict that it will take a fair bit of time to see the full effect of the current forcings, you are not correct. Now, you could try to make the argument that the effective relaxation times in the climate models are not realistic and the actual times are much shorter (as Schwartz did, although he has now had to backpedal quite a bit in the face of evidence that his method of determining the relaxation time systematically underestimates it in model systems where the correct answer is known). However, to claim that one cannot both account for the effect of Mt Pinatubo and have a reasonably long relaxation time for the climate system is demonstrably wrong.
EVERYBODY PANIC!!! #1
EVERYBODY PANIC!!! #2
EVERYBODY PANIC!!! #3
EVERYBODY PANIC!!! #4
EVERYBODY PANIC!!! #5
The climate is normal.
Merry Christmas, everyone!
Hungry for more charts & graphics? OK:
Pirates cause global cooling
Proof of global warming
Cheers!
Bill Marsh says:
For an exponential or logarithmic function, the question of regarding the region of linearity is related to the FRACTIONAL change in the function over the time period in question. I don’t think you can determine anything one way or the other from your intuition on what is a short or long period of time.
Well, I won’t quibble with you on what constitutes a large or small difference but considering that you were originally claiming our current CO2 concentrations (being ~37.5% of the way between 280ppm and 560ppm on a linear scale) constituted being >70% the way to a doubling on a log scale, I would say that the fact that it actually is only 46% of the way to a doubling does mean that the linear-to-log conversion doesn’t make nearly the difference that you thought it did.
See the rest of my post there. Given that we are out-of-equilibrium and given the large uncertainty in the value of the negative aerosol forcing, what we have seen is compatible with a very broad range of values for the equilibrium climate sensitivity. The simple fact is that the 20th and early 21st century temperature record just doesn’t provide us with very strong constraints on this value, which is why we have to look at other empirical evidence.
Considering the “man made” increase in carbon dioxide (from the burning of fossil fuels and tuna casseroles), shouldn’t we be seeing a corresponding 2-to-1 reduction in oxygen levels in respect to current carbon dioxide levels?
I’m at a loss to find any long-term data on the subject. Does anyone have any sources for such data?
Thanks,
-Uncle Larry
I do not think that Ben Kellet needs ice-core evidence that the Northern Hemisphere has warmer than now during the last 1,000 years. Greenland (so called because of its fertility) was actively farmed from about the eighth century until the little ice-age in the fourteenth cetury. This is borne out not only by archeology but also by contemporaneous written documents. It is still not warm enough to support much farming now. So if the ice cores do not show this pattern of warmer climates one must question either the accuracy of the ice-cores samples or the science which translates ice core samples into historical temperatures.
“Thousands of scientists reviewed the reports and were able to make as many critiques as they wanted.”
Last time I checked, the critiques were locked up in IPCC headquarters and someone was having trouble getting permission to visit and view them. Anyone know of an independent examination of them?
I love the 600-million year graph showing declining CO2 levels vs. temperature – my question would be, why are there apparent flat limits to temperature at 22C and 12C ? Since we’re at the lower limit, isn’t there only 1 direction to go? Temperature changes certainly weren’t caused by humans before.
BREAKING NEWS..!!!
————————————————————————-
Did Early Global Warming Divert A New Glacial Age?
ScienceDaily (Dec. 18, 2008) — The common wisdom is that the invention of the steam engine and the advent of the coal-fueled industrial age marked the beginning of human influence on global climate.
But gathering physical evidence, backed by powerful simulations on the world’s most advanced computer climate models, is reshaping that view and lending strong support to the radical idea that human-induced climate change began not 200 years ago, but thousands of years ago with the onset of large-scale agriculture in Asia and extensive deforestation in Europe.
What’s more, according to the same computer simulations, the cumulative effect of thousands of years of human influence on climate is preventing the world from entering a new glacial age, altering a clockwork rhythm of periodic cooling of the planet that extends back more than a million years.
“This challenges the paradigm that things began changing with the Industrial Revolution,” says Stephen Vavrus, a climatologist at the University of Wisconsin-Madison’s Center for Climatic Research and the Nelson Institute for Environmental Studies. “If you think about even a small rate of increase over a long period of time, it becomes important.”
Addressing scientists on Dec 17 at a meeting of the American Geophysical Union, Vavrus and colleagues John Kutzbach and Gwenaëlle Philippon provided detailed evidence in support of a controversial idea first put forward by climatologist William F. Ruddiman of the University of Virginia. That idea, debated for the past several years by climate scientists, holds that the introduction of large-scale rice agriculture in Asia, coupled with extensive deforestation in Europe began to alter world climate by pumping significant amounts of greenhouse gases — methane from terraced rice paddies and carbon dioxide from burning forests — into the atmosphere. In turn, a warmer atmosphere heated the oceans making them much less efficient storehouses of carbon dioxide and reinforcing global warming.
That one-two punch, say Kutzbach and Vavrus, was enough to set human-induced climate change in motion.
“No one disputes the large rate of increase in greenhouse gases with the Industrial Revolution,” Kutzbach notes. “The large-scale burning of coal for industry has swamped everything else” in the record.
But looking farther back in time, using climatic archives such as 850,000-year-old ice core records from Antarctica, scientists are teasing out evidence of past greenhouse gases in the form of fossil air trapped in the ice. That ancient air, say Vavrus and Kutzbach, contains the unmistakable signature of increased levels of atmospheric methane and carbon dioxide beginning thousands of years before the industrial age.
“Between 5,000 and 8,000 years ago, both methane and carbon dioxide started an upward trend, unlike during previous interglacial periods,” explains Kutzbach. Indeed, Ruddiman has shown that during the latter stages of six previous interglacials, greenhouse gases trended downward, not upward. Thus, the accumulation of greenhouse gases over the past few thousands of years, the Wisconsin-Virginia team argue, is very likely forestalling the onset of a new glacial cycle, such as have occurred at regular 100,000-year intervals during the last million years. Each glacial period has been paced by regular and predictable changes in the orbit of the Earth known as Milankovitch cycles, a mechanism thought to kick start glacial cycles.
“We’re at a very favorable state right now for increased glaciation,” says Kutzbach. “Nature is favoring it at this time in orbital cycles, and if humans weren’t in the picture it would probably be happening today.”
Importantly, the new research underscores the key role of greenhouse gases in influencing Earth’s climate. Whereas decreasing greenhouse gases in the past helped initiate glaciations, the early agricultural and recent industrial increases in greenhouse gases may be forestalling them, say Kutzbach and Vavrus.
Using three different climate models and removing the amount of greenhouse gases humans have injected into the atmosphere during the past 5,000 to 8,000 years, Vavrus and Kutzbach observed more permanent snow and ice cover in regions of Canada, Siberia, Greenland and the Rocky Mountains, all known to be seed regions for glaciers from previous ice ages. Vavrus notes: “With every feedback we’ve included, it seems to support the hypothesis (of a forestalled ice age) even more. We keep getting the same answer.”
Uncle Larry “shouldn’t we be seeing a corresponding 2-to-1 reduction in oxygen levels ”
It really would be 8 to 3, as the real ratio is O2=32 and C=12
The absence of any scientific rigor in Hansen’s immodest claims is patently evident from his miscasting of CO2 as a “forcing” and from his reliance upon an entirely novel notion of “positive feedback” by water vapor leading to a “runaway greehouse.”
CO2 produces not one calorie of energy; it merely absorbs and reradiates energy in a few narrow bands from a planetary surface thermalized entirely by insolation. It is thus a capacitance effect–a minor one, at that, compared to water vapor–and not any proper (i.e., energetic) forcing of the climate system.
Evaporation and moist convection combined rival radiation as a surface cooling mechanism, redistributing surface heat into the atmosphere. That heat is subsequently partially exchanged back and forth with the surface through radiative transfer. There can be no magic multiplication of total thermal energy through any proper feedback, however, in violation of conservation laws. The salutary effect of this so-called “greenhouse” is an elevated surface average along with a low-pass filtering of variations, which results in far smaller diurnal range than is oberved at the Moon. The harsh extermes found there are avoided.
At climatic time scales, the premise that increased CO2 concentrations lead to higher surface temperatures runs into a two-fold problem: temperature leads CO2 on millenial scales and the variables are virtually incoherent on multi-decadal basis. The weak millennial correlations are best expalined by outgassing from the oceans.
The basic physical fact seemingly ignored by Hansen is that one cannot obtain higher humidities aloft without an attendant increase in evaporative cooling at the surface and in cloudiness. The usual GCM model assumption of constant relative humidities is simply unrealistic, as is their parameterized treatment of “average” cloudiness. The danger we’re plainly witnessing is a runaway deification of results from unproven models.
foinavon ,
from the link you provided about aerosols: Role of Black Carbon on Global and Regional Climate Change
V. Ramanathan
http://oversight.house.gov/documents/20071018110734.pdf
VI.Major Source of Uncertainty: Emission Sources for BC
Our ability to model the effects of BCs in climate models is severely limited. One of the
main reason is the large uncertainty (factor of 2 or more) in the current estimates of the
emission of the organic (OC) and elemental carbon (EC) (See Bond et al. 2004 and
2007).. Furthermore, biomass burning contribute significantly to the emissions of OC
and EC and the historical trends (during the last 100 years) in these emissions are
unknown and models currently resort to ad-hoc methods such as scaling the current day emissions with past trends in population.
So we are talking factors of two, now.
I suspect all the references you give ( which unfortunately we cannot read since we do not subscribe to the publications) buried somewhere will be similar hedgings.
Do not get me wrong. It is fine that people explore all possible avenues, publish and defend them. That is normal in a scientific environment.
What is wrong is saying the science is settled, which you have adopted and shout loudly. The science is NOT settled. And trying to stampede the world politicians into disastrous energy policies on such flimsy and precarious arguments is unethical and immoral and downright dangerous.
Maybe the gods will take pity on us an bring on a few more winters like this so that AGW hotheads cool off.
Hey Foinavon,
Yeah, sorry, I did change the title accidentally (I had no ulterior motive other than being lazy 😉 ). I got it from this site without double checking properly and was in a rush.
It is:
Compo, G.P., and P.D. Sardeshmukh, 2008: Oceanic influences on recent continental warming. Climate Dynamics, doi: 10.1007/s00382-008-0448-9.
I’m pretty sure in that paper they don’t claim what the main cause of the oceans warming was (and that’s what I’m interested in) . They say it could be GHG but that it could also be due to natural causes and is a matter of active investigation. Sure GHG may have warmed the oceans but to what degree and were they the main driver of that warming. If so what evidence do we have to show that. Also, do we know what the thermal equilibrium time between atmosphere and ocean? Obviously that is vitally important in our understanding of climate sensitivity to CO2.
There was warming of the planet between say 1860 and 1940 and I find it hard to believe that that was due to CO2. If you look at the global mean surface temperature records, from 1860 to around 1915 the temperature goes up and then back down again even though there is very little change in CO2 (I think there might be a slight upwards trend in CO2). From 1860 to 1940 there is roughly a 0.5 degree change in temperature.
From the SIple Ice core I get the CO2 concentration in 1860 at around 289 ppm and in 1943 around 307 ppm. The global mean temperatures show a rise of around 0.5 degrees but by my calculations and your formula I get CO2 only being able to account for 0.26 of that or roughly half even assuming the oceans have come to thermal equilibrium and CO2 has done all its warming. If it hasn’t then the warming due to CO2 is less than 0.26.
Therefore, to me, there had to have been some natural (or other non CO2 forced) process at work and I’m still not convinced the IPCC (a Polemic of it’s own you’d have to admin) has enough evidence to claim that natural variation can’t have caused the warming of the latter 20th century. Claiming that increases in atmospheric CO2 was the main driver of temperature because you can’t think of any NV that could be responsible seems highly suspect to me because there have been these processes in the past, we may not know what they are and have fancy formulas for them but that doesn’t mean they don’t exist.
Using aerosols for canceling the warming reminds me of Ptolemy’s earth centric model of the solar system and the mini cycles mars and other planets took, they’re necessary to uphold ones view. Surely there is also another plausible explanation, that climate is not as sensitive to CO2 as assumed (2C02 = 3C). Is that not possible?
Chylek [2007] certainly seem to think it is. I think it would make more sense to me to assume that climate sensitivity is small until we are more sure of the effects of aerosols (i.e. uncertainties are reduced) and hence more certain of the climate sensitivity.
Surely you must agree statements like “the debate is over” and “science is settled” don’t help in these situations and seems to imply more certainty to Joe public like me than there really is. Then again I guess no one has actually defined what the “debate” was and which “science” has been settled.
If you assume that the temperature change is the result of CO2 and then compute the climate sensitivity to a doubling of CO2 and then using that result to prove the temperature change is the result of doubling the CO2 then this is circular reasoniong. I do not see how Mr. Hansen’s calculations are any more than circular reasoning. Please indicate where I am wrong.
Speaking of Hansen, when I look at his graph (C) on the second page of the following link, I see a regularly occurring temperature cycle.
http://www.giss.nasa.gov/meetings/arctic2007/pdf/aws_hansen.pdf
And when I look at where we are right now on the graph (time wise), the slope of those two (red and blue) curves preceding the temperature increases are very similar to the other 3 that happened in the past.
Unless I’m missing something, I see nothing abnormal in that graph for today’s time frame that hasn’t already occurred in the past 3 cycles.
sauerkraut (05:46:13) :
Cannot help but wonder if some of you folks are related to the creationista/ID folks.
What do ya alls think of comparison of the atmosphere to blood – specifically its function as a buffer? As with blood, it absorbs and absorbs and absorbs until a critical point is reached, whereby it all goes downhill from there.
And your bland generalisation adds “what value” to the conversation?
Comparing the buffering properties of blood with the Atmosphere – have you heard the term “Drawing a long bow”.
My commiserations for your recent loss.
Mark (12:52:08) :
Speaking of Hansen, when I look at his graph (C) on the second page of the following link, I see a regularly occurring temperature cycle.
http://www.giss.nasa.gov/meetings/arctic2007/pdf/aws_hansen.pdf
And when I look at where we are right now on the graph (time wise), the slope of those two (red and blue) curves preceding the temperature increases are very similar to the other 3 that happened in the past.
What you’re missing is the last 58 years of growth in CO2 (+~70ppm) and warming (~0.5ºC)!
anna v,
Yes there’s considerable uncertainty in the extent of the aerosol forcing. However the evidence indicates that it’s protecting us somewhat from the warming effects of hugely enhanced greenhouse gas concentrations. The nett aerosol contribution is a cooling one. As you have read in the paper that you’ve quoted from, Ramanathan is concerned about the possibility of removing the aerosol load since this will cause a significant enhancement of greenhouse warming (Ramanathan would like to find a means of selectively removing the warming contribution from black carbon).
I’m not shouting. I may have used the odd exclamation mark (!) but you’re the one using cpitalised bold text! As for “the science being settled”, one needs to be specific. Some science is essentially settled, some less so, and some is still controversial……that’s science for you!
It’s unfortunate that you don’t feel able to access the scientific literature (don’t you have a local University library?). It’s very easy to become mired in disinformation by resorting to blogs and other dodgy websites. If you use Google Scholar, you might be able to obtain downloadable versions of the papers. Or email the authors (email addresses obtainable with the free abstracts on journal websites. Some of the articles might be “Open Access”, and anything published by the major publicly funded research organisations (NASA Giss etc.) should be publically available free of charge.
I wouldn’t say that the papers I cited are “hedgings” at all. That’s rather presumptious! They present evidence that informs our understanding…
Just because the world is warming doesn’t mean that we don’t have winters. It’s quite a mild one over here in Blighty!
To: foinavon
“I’m not sure what you mean by “hot spot”. Can you enlighten us? It’s predicted that greenhouse warming will result in particularly strong warming in the high Northern latitudes due to efficient wind and ocean currents that transport excess heat from the equator, coupled with albedo feedbacks. is that what you mean?”
“anyway, please give us some clarification with respect to the “hot spot”
Let me try to fill the gap in your inconvenient memory loss. 😉
“Twelve IPCC climate model forecasts for the Fourth Assessment Report are shown at: http://ipccwg1.ucar.edu/wg1/Report/suppl/Ch10/Ch10_indiv-maps.html: see the column for Figure 10.7.
These model experiments follows the ‘A1B’ emissions scenario, a medium-range emissions trajectory out to 2100. The global average surface warming as of the end of the century for the GISS model is about 2.3 C.29. The tropospheric average is twice that, reaching 5 C, and the focal pattern emerges at the beginning of the forecast period. The visual pattern shown in Figure 5 is found in all 12 climate model simulations done for the recent IPCC report. In the Fourth Assessment Report Figure 9.1 (see http://ipccwg1.
ucar.edu/wg1/Report/AR4WG1_Pub_Ch09.pdf, page 675) a ‘hindcast’ is presented examining model-generated climate patterns for the interval 1890 to 1999. The Figure 5 pattern shows up in the greenhouse-only run (panel c) and, because the greenhouse forcing dominates the experiment,
in the summed changes (panel f). The clear implication of this graph is that a strong warming trend in the tropical troposphere ought to be underway already and should be the dominant pattern of change in comparison with all other forcings. The Figure 5 pattern is also shown in a model-generated ‘hindcast’ that simulates climatic changes from 1958 to 1999 under the assumption of strong GHG-warming, which was done for the US
Climate Change Science Program Report, Figure 1.3 Panels A and F, page 25, available at http://www.climatescience.gov/Library/sap/sap1-1/finalreport/default.htm. Again, the bright disc in the tropical troposphere is the dominant feature of the diagram.”
Now that you know what we are talking about, would you care to explain your view of the discrepancy?
More complete information here:
http://www.friendsofscience.org/assets/files/documents/T3tax.VVedition.pdf
Phil- you say “But it reflects ~75% of that insolation back into space so that its atmosphere actually receives less light from the sun than the Earth’s does.”
Indeed I did mention the difference in Albedo between Earth and Venus in my previous post-
“…but its Albedo is also higher than Earth (0.65 versus 0.3 for Earth).”
More accurate numbers-
Earth Albedo = 0.36, Venus = 0.65, Ratio V/E = 1.77
Top of atmosphere insolation Earth = 1367 W/m^2, Venus = 2600 W/m^2, Ratio = 1.9
Estimated surface insolation Earth = 1367*(1-0.36) = 875/m^2 at equator, noon sunward side
Venus = 2600*(1-0.65) = 910 W/m^2 at equator, noon on sunward side.
Pretty close to even by my estimates.
Surface temperature average Earth = 288 K, Venus = 737 K.
Biggest single difference between Venus and Earth- 92 times more total atmosphere on Venus (both atmospheres are good absorbers of infrared emission from the surface).
No runaway greenhouse needed.
Hansen is well aware of all of this, since I believe his PhD work involved modeling the atmosphere of Venus!
*sigh*