This is an attempt to redefine the graph made famous by Al Gore in An Inconvenient Truth that showed temperature leading CO2.
From a press release embargoed until 1PM EST 4/4:
Work that may clarify the relationship between carbon dioxide (CO2) levels and temperature at the end of the last ice age is presented in this week’s Nature. The study reveals that rising temperatures were preceded by CO2 increases during the last deglaciation, contrary to prior findings derived from ice cores that were thought to represent larger global patterns. These results support an important role for CO2 in driving global climate change.
Antarctic ice-core records indicate that CO2 may have influenced climate changes during the Pleistocene ice ages, which began around 2.6 million years ago and ended about 11,700 years ago. However, the exact role of CO2 in producing climate changes has remained unclear, partly because ice-core records only reflect local temperatures. To better understand the relationship between CO2 and global climate change, Jeremy Shakun and colleagues reconstruct global surface temperatures for the last deglaciation. They show that rising temperatures are correlated with, and generally lag behind, increasing levels of CO2.
The reconstructed global temperatures were produced using proxy records of temperature variability, such as those recorded in planktonic microorganisms. Anomalies in the correlations, such as in the Antarctic where the CO2 changes lag behind temperature, are explained by redistribution of heat between the Northern and Southern Hemispheres, the authors suggest.
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Here is the long form press release (h/t to junkscience.com):
Rising CO2 levels linked to global warming during last deglaciation
CORVALLIS, Ore. – Many scientists have long suspected that rising levels of carbon dioxide and the global warming that ended the last Ice Age were somehow linked, but establishing a clear cause-and-effect relationship between CO2 and global warming from the geologic record has remained difficult.
A new study, funded by the National Science Foundation and published in the journal Nature, identifies this relationship and provides compelling evidence that rising CO2 caused much of the global warming.
Lead author Jeremy Shakun, who conducted much of the research as a doctoral student at Oregon State University, said the key to understanding the role of CO2 is to reconstruct globally averaged temperature changes during the end of the last Ice Age, which contrasts with previous efforts that only compared local temperatures in Antarctica to carbon dioxide levels.
“Carbon dioxide has been suspected as an important factor in ending the last Ice Age, but its exact role has always been unclear because rising temperatures reflected in Antarctic ice cores came before rising levels of CO2,” said Shakun, who is a National Oceanic and Atmospheric Administration (NOAA) Post-doctoral Fellow at Harvard University and Columbia University.
“But if you reconstruct temperatures on a global scale – and not just examine Antarctic temperatures – it becomes apparent that the CO2 change slightly preceded much of the global warming, and this means the global greenhouse effect had an important role in driving up global temperatures and bringing the planet out of the last Ice Age,” Shakun added.
Here is what the researchers think happened.
Small changes in the Earth’s orbit around the sun affected the amount of sunlight striking the northern hemisphere, melting ice sheets that covered Canada and Europe. That fresh water flowed off of the continent into the Atlantic Ocean, where it formed a lid over the sinking end of the Atlantic Meridional Overturning Circulation – a part of a global network of currents that brings warm water up from the tropics and today keeps Europe temperate despite its high latitudes.
The ocean circulation warms the northern hemisphere at the expense of the south, the researchers say, but when the fresh water draining off the continent at the end of the last Ice Age entered the North Atlantic, it essentially put the brakes on the current and disrupted the delivery of heat to the northern latitudes.
“When the heat transport stops, it cools the north and heat builds up in the Southern Hemisphere,” Shakun said. “The Antarctic would have warmed rapidly, much faster than the time it takes to get CO2 out of the deep sea, where it was likely stored.
“The warming of the Southern Ocean may have shifted the winds as well as melted sea ice, and eventually drawn the CO2 out of the deep water, and released it into the atmosphere,” Shakun said. “That, in turn, would have amplified warming on a global scale.”
The researchers constructed a record of global surface temperature from 80 temperature reconstructions spanning the end of the Ice Age and found that average temperature around the Earth correlated with – and generally lagged behind – rising levels of CO2.
Peter Clark, an Oregon State University scientist and co-author on the paper, said changes in solar radiation were the likely trigger for the series of effects that followed. His 2009 study, published in Science, confirmed an earlier theory that wobble in the Earth’s axis, which changes the amount of sunlight captured by Earth, first caused melting of the large northern ice sheets.
“It has long been known that Earth’s slow wobble is caused primarily by the gravitational influences of the larger planets, such as Jupiter and Saturn, which pull and tug on the Earth in slightly different ways over periods of thousands of years,” said Clark, a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences.
Shakun said there is “an enormous amount” of carbon sequestered in the deep ocean.
“The Southern Ocean is connected to all the deep ocean basins,” he pointed out, “so the most likely mechanisms to draw it out of the ocean were certainly there.”
The question now, the researchers say, is how human-generated carbon dioxide will affect the planet when there isn’t an ice age.
“CO2 was a big part of bringing the world out of the last Ice Age,” Shakun said, “and it took about 10,000 years to do it. Now CO2 levels are rising again, but this time an equivalent increase in CO2 has occurred in only about 200 years, and there are clear signs that the planet is already beginning to respond.”
“While many of the details of future climate change remain to be figured out, our study bolsters the consensus view that rising CO2 will lead to more global warming,” Shakun added.
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The paper is at http://www.nature.com/nature/journal/v484/n7392/full/nature10915.html and named:
Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation
Jeremy D. Shakun, Peter U. Clark, Feng He, Shaun A. Marcott, Alan C. Mix, Zhengyu Liu, Bette Otto-Bliesner, Andreas Schmittner & Edouard Bard
Abstract:
The covariation of carbon dioxide (CO2) concentration and temperature in Antarctic ice-core records suggests a close link between CO2 and climate during the Pleistocene ice ages. The role and relative importance of CO2 in producing these climate changes remains unclear, however, in part because the ice-core deuterium record reflects local rather than
global temperature. Here we construct a record of global surface temperature from 80 proxy records and show that temperature is correlated with and generally lags CO2 during the last (that is, the most recent) deglaciation. Differences between the respective temperature changes of the Northern Hemisphere and Southern Hemisphere parallel variations in the strength of the Atlantic meridional overturning circulation recorded in marine sediments. These observations, together with transient global climate model simulations, support the conclusion that an antiphased hemispheric temperature response to ocean circulation changes superimposed on globally in-phase warming driven by increasing CO2 concentrations is an explanation for much of the temperature change at the end of the most recent ice age.
METHODS SUMMARY
The data set compiled in this study contains most published high-resolution
(median resolution, 200 yr), well-dated (n5636 radiocarbon dates) temperature
records from the last deglaciation (see Supplementary Information for the full
database). Sixty-seven records are from the ocean and are interpreted to reflect sea
surface temperatures, and the remaining 13 record air or lake temperatures on
land. All records span 18–11 kyr ago and,85% of them span 22–6.5 kyr ago. We
recalibrated all radiocarbon dates with the IntCal04 calibration (Supplementary
Information) and converted proxy units to temperature using the reservoir corrections
and proxy calibrations suggested in the original publications. An exception
to this was the alkenone records, which were recalibrated with a global
core-top calibration41. The data were projected onto a 5u35u grid, linearly
interpolated to 100-yr resolution and combined as area-weighted averages. We
used Monte Carlo simulations to quantify pooled uncertainties in the age models
and proxy temperatures, although we do not account for analytical uncertainties
or uncertainties related to lack of global coverage and spatial bias in the data set. In
particular, the records are strongly biased towards ocean margins where high
sedimentation rates facilitate the development of high-resolution records. Given
these issues, we focus on the temporal evolution of temperature through the
deglaciation rather than on its amplitude of change. The global temperature stack
is not particularly sensitive to interpolation resolution, areal weighting, the
number of proxy records, radiocarbon calibration, infilling of missing data or
proxy type. Details on the experimental design of the transient model simulations
can be found in ref. 25.
The temperature stacks and proxy data set are available in Supplementary Information.
Full Methods and any associated references are available in the online version of
the paper at www.nature.com/nature.
PDF files
-
- Supplementary Information (9.2M)
- This file contains Supplementary Text and Data, Supplementary Figures 1-30, Supplementary Tables 1-3, additional References and Supplementary Appendices 1-2.
Excel files
-
- Supplementary Data (2.4M)
- This file contains Supplementary Data.
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Don Easterbrook has some initial thoughts on the Nature paper.
The paper is based on many assumptions without supporting data. Here are a few examples:
1. They assume that CO2 is capable of causing climate changes, even though 95% of the greenhouse gas (GHG) effect is from water vapor. In order to seriously consider CO2 as a causal mechanism, you first need to prove that very tiny increases in CO2 do indeed increase atmospheric water vapor. However, during recent warming, purported to be caused by increased CO2, atmospheric water vapor has not gone up, it has decreased slightly. CO2 by itself cannot cause significant warming because there is little of it in the atmosphere (0.038%) and CO2 accounts for only a few percent of the GHG effect.
2. They assume that the AMOC is the only driver of climate change, totally ignoring the influence of the Pacific Ocean, which covers almost half of the Earth’s surface and we can see in the modern data a strong influence of ENSO as a driver of climate changes (actually a closer correlation than the AMOC). They offer no evidence that the AMOC is the main and only driver of climate change.
3. They assume a hemispheric ‘see-saw’ of climate changes in which the North and South Hemispheres are out of phase, despite strong evidence in both hemisphere that climate changes were closely simultaneous, not out of phase with one another (Easterbrook, 2011).
4. The dismiss all other causal mechanisms by simply stating that they are only of ‘regional importance’, similar to the tactic of dismissing the MWP and Little Ice Age as only regional climate changes, not global. They also totally ignore the complete lack of correlation of CO2 with Holocene climate changes. They don’t even mention the very strong correlation of variation in 10Be and 14C with climate changes, suggesting a solar cause.
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The Antarctic Ice core graph is particularly troublesome.
In the long scale graph at top, I pointed out that the resolution of the temperature reconstruction diminished as the sample got older. Willis responded to my query with this:
The resolution for temperature drops, as does the CO2 resolution, because the ice is getting more compressed and so there is more and more time between equally spaced samples. Here’s one of my old graphs of the same data, showing the same phenomenon:
Where I think they go wrong is the claim that they can somehow reconstruct, not just the couple thousands of years of temperature that Mann claimed, but nearly a million years of temperature … and that the timelines for the two wouldn’t have errors.
My rule of thumb about these kinds of things is, no error bars … no science.
w.
Other rebuttals are in the works. I will add to this posting as they develop.
Pat Michaels writes to junkscience.com:
I am very unexcited about this. I have always thought that the timing of carbon dioxide changes and warming/cooling is pretty much irrelevant… What is interesting about this latest “finding” is that it demonstrates, yet again, the unfalsifiability of climate change “science”. The standard argument on the ice cores has been that temperature preceding carbon dioxide changes is simply evidence for positive feedback rather than lack of forcing. Now the argument will revert back to the other way around — that CO2 causes all the major pleistocene (which we are still in — see Greenland) climate fluctuations.
About that carbon dioxide–it’s just another attempt to explain the true mystery of climate change, which is why major glaciations ever go away.
My mantra is that “it’s not the heat, it’s the sensitivity”, which is obviously overestimated in climate models, for a variety of reasons that should be obvious.
Tom V. Segalstad Associated Professor of Resource and Environmental Geology, at the
University of Oslo writes:
There are some serious problems with ice cores.
I’ll be surprised if the new Nature paper cites our paper by Jaworowski, Segalstad & Ono (1992): Do glaciers tell a true atmospheric CO2 story? in the professional peer-reviewed Elsevier journal “Science of the total environment”, Vol. 114, pp. 227-284 (1992). The paper is available on my website here: http://www.co2web.info/stoten92.pdf
There’s a follow-up paper (abstract) on the stable isotope temperature measurement technique in ice cores here: http://www.co2web.info/aig.pdf
I checked the references of the Shakun et al paper published today, and the paper Segalstad mentions is not part of the references section. I guess it was too inconvenient to mention.
Without prejudice regarding the additional bobbers and spinners the authors have added to the Ptolmaic system of temperature control by CO2, remember that CO2 leading temperature is a necessary condition for causation, but not a sufficient one. The lead of temperature during periods of glacation, too great to be obfuscated, doesn’t prove that temperature controls CO2, it merely makes this the only plausible relationship.
Looking at the graph, as CO2 causes the global temperature to go up, wouldn’t you expect that delayed warming to feed back into the Antarctic temperatures which are already being raised by the sun? Or does the Antarctic respond quickly to CO2 forcing where the rest of the world doesn’t?
There are sections of the graph where the global temperature is rising while the Antarctic is cooling. What is the cause of the localised cooling in the Antarctic? Variations in the Milankovitch cycle?
(BTW what are the units for Antarctic temperature? It doesn’t appear to be degrees C)
Elmer, are you seriously going to use the jailed, fraudulant Young Earth Creationist, Kent Hovind as your scientific advisor on the subject of climate change? Really? I’m not even going to bother delving into his “The Lost Squadron” evidence for a young Earth because it is so preposterous. I can only wonder if the other climate denial people in here turn on you as vehemently as they turn on AGW proponents like me. I doubt they will though. They have been known to accept any sort of “evidence” no matter how poor, to suit their cause.
The finding of Lindzen and Choi that the planet’s feedback response to a change in forcing is negative (clouds in the tropics increase or decrease to reflect more or less energy off into space which) removes the forcing amplification which is required to try to explain why the weakest of the orbital parameters eccentricity can cause the 100 kyr glacial/interglacial cycle.
The discussion is pointless and goes in circles as there are multi incorrect mechanisms posited to explain what is observed. Naturally when the mechanisms are incorrect, the proxies are misinterpreted or in the case of the problem manipulated to try to save the incorrect mechanism.
Insolation changes, due to orbital changes, are not the cause of the glacial/interglacial cycle. Temperature changes cannot and do not cause of the observed glacial/interglacial atmospheric changes in CO2. The long term reduction in atmospheric CO2 is not due to the Himalayas forming.
The theoretical assumed mechanism what controls and varies atmospheric CO2 is incorrect. The posited cause of the glacial/interglacial cycles (changes in summer insolation at 60 degree latitude north is incorrect.)
Look at figure 3 which is Greenland Icesheet temperature over the last 12,000 years Vs atmospheric CO2.
The planet warms and cools during the Dansgaard-Oeschger cycles. The Dansgaard-Oechger climate change is not an event. It is a cycle. It is a cycle.
Question 1: What the heck causes the Dansgaard-Oeschger cyles? That is rhetorical question. As I know what causes it. Hint there are cosmogenic isotope changes each and every time during the Dansgaard-Oeschger cycle. The late Gerald Bond was able to track 23 cycles. The same suspect is always at the scene of the crime. It is the bloody sun.
The assumed model for the sun is fundamentally incorrect. The sun cyclically causes a very sever climate change. The paleoclimatic data unambiguously shows there are cyclic abrupt climate changes such as the Younger Dryas. The paleoclimatic specialist refer to the Younger Dryas as Heinrich event 0. The Heinrich event is not a stupid event it is cycle. It is a cycle. An event is something that occurs randomly due to for instance comet impacts. A climate cycle requires a cyclic forcing function. A cycle is something that will happen again. All of the past interglacials ended abruptly.
The cyclic Heinrich abrupt climate change cycles are not caused by CO2 changes. The Dansgaard-Oeschger cycle is not caused by CO2 changes.
Question 2: Why the heck does CO2 not change during the Dansgaard-Oeschger cycle? Planetary temperature increases and decrease. That also is rhetorical question.
The planet cooled during the Holocene interglacial period. Why does CO2 gradually rise? Temperature is decreasing.
http://climate4you.com/images/GISP2%20TemperatureSince10700%20BP%20with%20CO2%20from%20EPICA%20DomeC.gif
http://climate4you.com/
http://arxiv.org/abs/physics/0612145v1
The Antarctic climate anomaly and galactic cosmic rays
Borehole temperatures in the ice sheets spanning the past 6000 years show Antarctica repeatedly warming when Greenland cooled, and vice versa (Fig. 1) [13, 14]. North-south oscillations of greater amplitude associated with Dansgaard-Oeschger events are evident in oxygenisotope data from the Wurm-Wisconsin glaciation[15]. The phenomenon has been called the polar see-saw[15, 16], but that implies a north-south symmetry that is absent. Greenland is better coupled to global temperatures than Antarctica is, and the fulcrum of the temperature swings is near the Antarctic Circle. A more apt term for the effect is the Antarctic climate anomaly.
http://www.agu.org/pubs/crossref/2002/2000PA000571.shtml
On the 1470-year pacing of Dansgaard-Oeschger warm events
The oxygen isotope record from the Greenland Ice Sheet Project 2 (GISP2) ice core was reanalyzed in the frequency and time domains. The prominent 1470-year spectral peak, which has been associated with the occurrence of Dansgaard-Oeschger interstadial events, is solely caused by Dansgaard-Oeschger events 5, 6, and 7. This result emphasizes the nonstationary character of the oxygen isotope time series. Nevertheless, a fundamental pacing period of ∼1470 years seems to control the timing of the onset of the Dansgaard-Oeschger events. A trapezoidal time series model is introduced which provides a template for the pacing of the Dansgaard-Oeschger events. Statistical analysis indicates only a ≤3% probability that the number of matches between observed and template-derived onsets of Dansgaard-Oeschger events between 13 and 46 kyr B.P. resulted by chance. During this interval the spacing of the Dansgaard-Oeschger onsets varied by ±20% around the fundamental 1470-year period and multiples thereof. The pacing seems unaffected by variations in the strength of North Atlantic Deep Water formation, suggesting that the thermohaline circulation was not the primary controlling factor of the pacing period.
Atmospheric CO2 does not change significantly when temperature changes. There is an estimated maximum change of 30 ppm in CO2 for the total temperature change from glacial/interglacial and visa versa. Due the change in ocean salinity atmospheric CO2 increases when there is there is more ice in the ice sheets. As the vast regions of the biosphere is covered by ice and there is massive reduction in rainforest (roughly 30% of the Amazon is converted from rainforest to savanna) there is massive reduction in vegetation which increases the amount of the CO2. The total net change in atmospheric CO2 due to ice sheets forming causing a saltier ocean and the reduction in vegetation is no net change in atmospheric CO2 and likely an increase in atmospheric CO2. (Volcanic input continues yet there is a reduction in vegetation to remove the CO2.)
There is no explanation as to what causes the reduction of 80 ppm to 100 ppm of atmospheric CO2 during the glacial/interglacial cycle. That is the so called Holy Grail of the carbon cycle specialists.
http://www.up.ethz.ch/education/biogeochem_cycles/reading_list/sigman_nat_00.pdf
A reasonable estimate for ice age ocean cooling of 2.5C in the polar surface and 5C in the low-latitude surface leads to a CO2 decrease of 30 p.p.m.v., with the low-latitude and polar temperature changes playing roughly equivalent roles in this decrease. It has recently been noted that ocean general circulation models predict a greater sensitivity of CO2 to low-latitude surface conditions than do simple ocean box models like CYCLOPS17. However, the significance of this observation is a matter of intense debate.
An opposing effect on atmospheric CO2 to that of glacial/interglacial temperature change is provided by the increased salinity of the glacial ocean, due to the storage of fresh water on land in extensive Northern Hemisphere ice sheets. Based on the approximately 120m depression of sea level during the last ice age18, the whole ocean was about 3% saltier than it is today. All else being constant, this increase would have reduced the solubility of CO2 in sea water and raised atmospheric CO2 by 6.5 p.p.m.v. Taking the estimated temperature and salinity effects together, we would expect the atmospheric CO2 concentration of the ice age world to have been 23.5 p.p.m.v. lower. Folding in the effect of a 500 Pg C transfer from the continents to the ocean/atmosphere system, we are left with an 8.5 p.p.m.v. decrease in CO2 (Table 1). There are uncertainties in each of these effects, but it seems that most of the 80±100 p.p.m.v. CO2 change across the last glacial/interglacial transition must be explained by other processes. We must move on to the more complex aspects of the ocean carbon cycle.
Timing of abrupt climate change: A precise clock by Stefan Rahmstorf
Many paleoclimatic data reveal a approx. 1,500 year cyclicity of unknown origin. A crucial question is how stable and regular this cycle is. An analysis of the GISP2 ice core record from Greenland reveals that abrupt climate events appear to be paced by a 1,470-year cycle with a period that is probably stable to within a few percent; with 95% confidence the period is maintained to better than 12% over at least 23 cycles. This highly precise clock points to an origin outside the Earth system; oscillatory modes within the Earth system can be expected to be far more irregular in period.
Prof. George Lytwynyshyn of Northwestern University (Evanston, Illinois) teaches that, in the past, temperature preceded the rise in carbon dioxide levels. He presented excellent data to support this and contends that the Gore-Hansen et.al theory that carbon dioxide causes warming is bogus. I believe his theory is the accurate one (he is a geologist & engineer by training, very smart guy).
The Gore-Hansen et al theory? Would you care to provide a reference to any peer reviewed papers put forward by Gore?
Steven Mosher: The only people who deny that C02 will warm the planet are those who fail to understand the experimental evidence.
There are people who think that the experimental evidence does not rule out negative feedbacks in the atmosphere. So as written, that sentence is false.
It seems that many posters here would like to ignore some important new facts that were presented in the paper. Instead they rant about “Talebanic AGW fascist-fanaticism”.
Previously, the only data on temperature that went along with the CO2 data from the Antarctic cores was the local Antarctic temperature. The new information is that global proxies show that global temperature lagged the Antarctic temperature so that it looks like CO2 increases could have driven a good part of the temperature change.
The mechanism presented to explain this is physically reasonable. The lighter fresh water, melted by the increase in solar energy in the Northern Hemisphere, blocks surface ocean current from the warmer regions of the Atlantic and causes heat to back up into the Southern Hemisphere. The fact is that warming in the Arctic will certainly reduce the flux of warm surface water from the tropics to the Arctic. The vast southern ocean is a sink of CO2, so warming of the southern ocean will release CO2. The greenhouse effect is real, as is the feedback effect of water vapor. These effects, plus the decrease in reflectivity due to reduced ice and snow in the Northern Hemisphere, are going to reinforce the initial warming effect of the warming due to the combination of axial tilt and orbital precession.
This is a viable theory and does not deserve to be ridiculed. If people are skeptical, the burden is on them to provide an alternative explanation for what was observed.
For the most part, what we get from the vast majority of posters is invective. It is a sorry spectacle.
CRS, DrPH says:
April 6, 2012 at 11:55 am
“Prof. George Lytwynyshyn of Northwestern University (Evanston, Illinois) teaches that, in the past, temperature preceded the rise in carbon dioxide levels. He presented excellent data to support this and contends that the Gore-Hansen et.al theory that carbon dioxide causes warming is bogus. I believe his theory is the accurate one (he is a geologist & engineer by training, very smart guy).”
The professor is not doing research in this area, even though he is a smart guy.
It seems that he is a part timer. His listing at Northwestern says:
George R. Lytwynyshyn Principal, Supply Chain Risk Management, Inc. Environmental Management
In fact, unitil this new paper was published, all that was available was the Antarctic temperature data, along with the CO2 data, which showed an 800 year lag between warming of the Antarctic and CO2 increase. Obviously he could not have known about the new paper which looked at global temperatures rather than Antarctic temperatures and shows a much shorter lag.
Your claim that Gore and / or Hansen originated the theory that CO2 caused warming shows that either you are a poor student, or the good professor did not know what he was talking about. The theory that CO2 causes global warming originated with John Tyndall and who did research on the spectrum of atmospheric gases in 1859. The idea that human industrial emissions of CO2 will warm the earth was proposed by Svante Arrhenius in 1896.
Eric Adler says:
“If people are skeptical, the burden is on them to provide an alternative explanation for what was observed.”
First, there are no observations other than ice cores and similar proxies, which all show that rises in CO2 follow rises in temperature. And second, the burden is on the authors, not on skeptics. Skeptics have no burden to provide an “alternate explanation” for anything. The onus is entirely on the promoters of this already debunked conjecture. Ice core evidence shows that CO2 follows temperature, and there is direct observational evidence that even on short time scales CO2 follows temperature.
The planet itself is falsifying Shakun’s ridiculous paper. And there is a mountain of geological evidence showing that temperature leads CO2. This fatally flawed paper is a desperate attempt to overturn real world evidence, and the ‘say anything’ crowd clings to it like a drowning man clings to a cork.
joeldshore says:
April 5, 2012 at 6:19 pm
“I don’t need to waste my time proving everything to your satisfaction (which is impossible anyway because your objections are not based on science but on ideology). It is the accepted view in the scientific community. If you don’t want to believe it, you are welcome not to. It will just make you look “AGW skeptics” look even sillier in the eyes of the scientific community (if such a thing is possible).”
So, why do you post? You appear to be an obsessive-compulsive ideologue who is screaming just like the rest of them as your little scam melts before your eyes. I will ask again. Why do you post?
Septic Matthew/Matthew R Marler says:
April 6, 2012 at 1:57 pm
“Steven Mosher: “The only people who deny that C02 will warm the planet are those who fail to understand the experimental evidence.”
There are people who think that the experimental evidence does not rule out negative feedbacks in the atmosphere. So as written, that sentence is false.”
“Sceptic” Matthew,
The preponderance of the evidence is that the long term feedback is positive. The papers claiming negative feedback have been shown to be flawed.
Even if there is some negative feedback, the planet will still get warmer, but the warming would be less than what would occur due to CO2 alone.
So the sentence is correct.
Eric Adler says:
“The theory that CO2 causes global warming …”
Get your terms straight. There is no “theory” that CO2 causes global warming or anything else. As for AGW, that is a conjecture. It may be true. But it is not empirically testable or falsifiable, thus it is a conjecture.
And the statement…
“The preponderance of the evidence is that the long term feedback is positive. The papers claiming negative feedback have been shown to be flawed.”
…should be under the heading “Science Fiction”. “Preponderance” means more than half. Therefore [even if that term is used correctly, which it is not], that means there exists contrary evidence, thus falsifying your belief system. Septic Matthew is correct, as verified by the ultimate Authority, planet earth.
Smokey says:
“First, there are no observations other than ice cores and similar proxies, which all show that rises in CO2 follow rises in temperature. And second, the burden is on the authors, not on skeptics. Skeptics have no burden to provide an “alternate explanation” for anything. The onus is entirely on the promoters of this already debunked conjecture. Ice core evidence shows that CO2 follows temperature, and there is direct observational evidence that even on short time scales CO2 follows temperature.”
Your brain is so clouded you don’t even understand what the paper is saying even when it is explained. The authors have met their burden. Their proxies show that CO2 does not lag global temperature change. The ice core only gives temperature change in the Antarctic.
Eric Adler says:
“The authors have met their burden.” Wishful thinking. And:
” The ice core only gives temperature change in the Antarctic.”
Listen up, Skippy: There are numerous ice core bore holes from both hemispheres. The temperature fluctuations in both hemispheres are in synch.
Dream on in your own private reality. The fact is that the Shakun paper is crap, as this and this make crystal clear. I could explain it to you, but I can’t understand it for you. Cognitive dissonance controls alarmist numpties, and there is apparently no cure in your case.
[snip. Read the site Policy. Labeling those with a different view as “deniers” is a pejorative that is not tolerated on the internet’s Best Science & Technology site. ~dbs, mod.]
So why does the temperature drop at the start of a new ice age but carbon dioxide levels stay high for thousands of years afterwards? And, why do carbon dioxide levels shoot up with an almost clockwork like regularity every 120000 years or so and then shoot down again? Answers please on a postcard to WUWT.
For the real truth about which comes first, one must obviously go to the source:
http://www.realclimate.org/index.php/archives/2004/12/co2-in-ice-cores/
There it is, in black-and-white; the temperature moves before the CO2.
I haven’t had a chance to read through all the comments so it may have been mentioned already but Shakuns work doesn’t seem to acknowledge the Huybers/Langmuir study about the feedback between deglaciation, volcanism and atmospheric CO2. I’ll link it below but I’m curious why a strong suggestion of an increase of 20-80 ppm CO2 from that cycle during that period would be ignored like that?
http://dash.harvard.edu/bitstream/handle/1/3659701/Huybers_FeedbackDeglaciation.pdf?sequence=1
SBMorris,
Thanks for pointing out the paper on the possible volcanic feedback due to additional emissions of CO2 between 12Ka and 7Ka BP. If you look at the graph, you can see that CO2 plateau’s between about 15Ka and 12.5Ka BP and then rises sharply once again.
Eric,
Isn’t that paper suggesting the increase in CO2 is due to increased volcanism as a result of deglaciation over that time, not due to increased emissions? I’m not sure if you’re saying that CO2 caused that or not so sorry if I’m misinterpreting/misreading you. If the argument is ‘CO2 is the driver, therefore…’ I can see why you’re saying that but I certainly don’t see it in the data, those proxies are all over the place but still suggest to me that CO2 chases temp..
The graph seems to line up but it isn’t acknowledged in Shakun’s paper as such from what I can tell.
Eric Adler says:
April 6, 2012 at 5:41 pm
It seems that many posters here would like to ignore some important new facts that were presented in the paper. Instead they rant about “Talebanic AGW fascist-fanaticism”.
Previously, the only data on temperature that went along with the CO2 data from the Antarctic cores was the local Antarctic temperature. The new information is that global proxies show that global temperature lagged the Antarctic temperature so that it looks like CO2 increases could have driven a good part of the temperature change.
My “rant” about Talebanic AGW was directly in the context of the call by Kari Norgaard, Oregon University, to have AGW skeptics consigned to psyciartic treatment (with implication of forcible consignment). Who is the one here using extremist and even violent language?
My point that you did not address was a straightforward scientific one – due to the Younger Dryas there were two abrupt global temperature rises separated by just over a thousand years at the start of the current interglacial. This provides an element of ambiguity to the precise timing of rises of both CO2 and temperatures, with temperature rise being effectively smeared over a long period. This gives scope for cherry-picking of proxies to paint a picture of (some) temp rises following CO2 rise.
SMorris says:
April 7, 2012 at 3:17 pm
“Eric,
Isn’t that paper suggesting the increase in CO2 is due to increased volcanism as a result of deglaciation over that time, not due to increased emissions? I’m not sure if you’re saying that CO2 caused that or not so sorry if I’m misinterpreting/misreading you. If the argument is ‘CO2 is the driver, therefore…’ I can see why you’re saying that but I certainly don’t see it in the data, those proxies are all over the place but still suggest to me that CO2 chases temp..
The graph seems to line up but it isn’t acknowledged in Shakun’s paper as such from what I can tell.”
The abstract seems to say that the volcanism contributed to increase in CO2 which further increased the warming and caused more deglaciation.
“If such a large volcanic output of CO2 occurs, then volcanism forges a positive feedback between glacial variability and atmospheric CO2 concentrations: deglaciation increases volcanic eruptions, raises atmospheric CO2, and causes more deglaciation.”
This is an alternative to the theory that CO2 causes warming which causes more emission of CO2 from the ocean.
Both theories say that CO2 causes more warming as a feedback mechanism.
Eric Adler says:
“…the theory that CO2 causes warming which causes more emission of CO2 from the ocean… Both theories say that CO2 causes more warming…”
Ignorance on display. There is no such ‘theory’ regarding CO2. None. It is all conjecture, and nothing more.
Mike says:
April 6, 2012 at 9:14 pm
[snip. Read the site Policy. Labeling those with a different view as “deniers” is a pejorative that is not tolerated on the internet’s Best Science & Technology site. ~dbs, mod.]
I would like to apologise to any people with an alternate view to the AGW consensus who may have taken offence to being referred to as “deniers” or “denialists”. Having read the Policy I am aware now that personal attacks and namecalling is not on and as such I will not engage in that behaviour on this site any longer.
I would however like to refer the moderator to the numerous breaches of the Policy by a number of posters in here. I believe that being told to STFU and being referred to as fascists, warmists, and alarmists would be in breach of the very same policy, unless of course there are different standards for different posters based upon their position? That would by extremely disppointing. Surely someone claiming to be the “internet’s Best Science & Technology site” would not wish to be seen as a bastion of double standards and hypocrisy?
But to return to my legitimate comment which you also snipped out. I am curious as to how many of the posters in here who are criticising the Shakun et al paper have actually read the paper and its supplements in their entirety and really understood it? I get the impression that a number of you haven’t but have instead tried eyeballing the graphs as presented in here looking for lags before making uninformed statements. As for those of you who have read it and feel you have legitimate informed criticisms of their methods, results or interpretations, how many of you are actually going to write it up and submit for publication? Any takers?
[one strives for uniformity in moderation, but hey, we’re all human. Comments noted ~ac, mod]
Full text of this excellent article is here:
http://sciences.blogs.liberation.fr/files/shakun-et-al.pdf
Alex