Posted on 04/04/2012 12:04:10 PM PDT by Ernest_at_the_Beach
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. Shakun1, 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.
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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.
Sounds like they are trying to torture the data into supporting a predetermined conclusion again.
Ice core data has been consistent in study after study in saying that CO2 levels are a trailing indicator. CO2 responds to temperature change. It does not cause the change. There isn't enough CO2 to do the job. Water vapor is by far the most potent "greenhouse gas".
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| '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.' Wow, so planetary orbital calculations ought to be impossible to analyze/verify/predict, right Clark?
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Yup, just tweak the data until it says what you want. That’s what passes for “science” with the AGW crowd...
ABSTRACT:
"Carbon dioxide in the atmosphere [historically] is the product of oceanic respiration due to the well-known but under-appreciated solubility pump. Carbon dioxide rises out of warm ocean waters where it is added to the atmosphere. There it is mixed with residual and accidental CO2, and circulated, to be absorbed into the sink of the cold ocean waters. Next the thermohaline circulation carries the CO2-rich sea water deep into the ocean. A millennium later it appears at the surface in warm waters, saturated by lower pressure and higher temperature, to be exhausted back into the atmosphere. Throughout the past 420 millennia, comprising four interglacial periods, the Vostok record of atmospheric carbon dioxide concentration is imprinted with, and fully characterized by, the physics of the solubility of CO2 in water, along with the lag in the deep ocean circulation.
Notwithstanding that carbon dioxide is a greenhouse gas, atmospheric carbon dioxide has neither caused nor amplified global temperature increases. Increased carbon dioxide has been an effect of global warming, not a cause [historically -etl]. Technically, carbon dioxide is a lagging proxy for ocean temperatures. When global temperature, and along with it, ocean temperature rises, the physics of solubility causes atmospheric CO2 to increase.
If increases in carbon dioxide, or any other greenhouse gas, could have in turn raised global temperatures, the positive feedback would have been catastrophic. While the conditions for such a catastrophe were present in the Vostok record from natural causes, the runaway event did not occur. Carbon dioxide does not accumulate in the atmosphere."
http://www.rocketscientistsjournal.com/2006/10/co2_acquittal.html
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So, greenhouse [effect] is all about carbon dioxide, right?
Wrong. The most important players on the greenhouse stage are water vapor and clouds [clouds of course aren't gas, but high level ones do act to trap heat from escaping, while low-lying cumulus clouds tend to reflect sunlight and thereby help cool the planet -etl]. Carbon dioxide has been increased to about 0.038% of the atmosphere (possibly from about 0.028% pre-Industrial Revolution) while water in its various forms ranges from 0% to 4% of the atmosphere and its properties vary by what form it is in and even at what altitude it is found in the atmosphere.
In simple terms the bulk of Earth's greenhouse effect is due to water vapor by virtue of its abundance. Water accounts for about 90% of the Earth's greenhouse effect -- perhaps 70% is due to water vapor and about 20% due to clouds (mostly water droplets), some estimates put water as high as 95% of Earth's total tropospheric greenhouse effect (e.g., Freidenreich and Ramaswamy, 'Solar Radiation Absorption by Carbon Dioxide, Overlap with Water, and a Parameterization for General Circulation Models,' Journal of Geophysical Research 98 (1993):7255-7264).
The remaining portion comes from carbon dioxide, nitrous oxide, methane, ozone and miscellaneous other 'minor greenhouse gases.' As an example of the relative importance of water it should be noted that changes in the relative humidity on the order of 1.3-4% are equivalent to the effect of doubling CO2.
http://www.junkscience.com/Greenhouse/
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Water Vapor Rules the Greenhouse System
Water vapor constitutes Earth's most significant greenhouse gas, accounting for about 95% of Earth's greenhouse effect (4). Interestingly, many 'facts and figures' regarding global warming completely ignore the powerful effects of water vapor in the greenhouse system, carelessly (perhaps, deliberately) overstating human impacts as much as 20-fold.
Water vapor is 99.999% of natural origin. Other atmospheric greenhouse gases, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and miscellaneous other gases (CFC's, etc.), are also mostly of natural origin (except for the latter, which is mostly anthropogenic).
Human activities contribute slightly to greenhouse gas concentrations through farming, manufacturing, power generation, and transportation. However, these emissions are so dwarfed in comparison to emissions from natural sources we can do nothing about, that even the most costly efforts to limit human emissions would have a very small-- perhaps undetectable-- effect on global climate.
http://www.geocraft.com/WVFossils/greenhouse_data.html
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Water Vapor Confirmed As Major Player In Climate Change
ScienceDaily (Nov. 18, 2008) — Water vapor is known to be Earth's most abundant greenhouse gas, but the extent of its contribution to global warming has been debated. Using recent NASA satellite data, researchers have estimated more precisely than ever the heat-trapping effect of water in the air, validating the role of the gas as a critical component of climate change.
http://www.sciencedaily.com/releases/2008/11/081117193013.htm
I'd rather wait for more advanced batteries available by 2020 based on dry-electrode lithium-air and carbon nanotube ultracapacitor designs, which will result in long-range electric cars that spew NO exhaust of any type.
I'd rather wait for more advanced batteries available by 2020 based on dry-electrode lithium-air and carbon nanotube ultracapacitor designs, which will result in long-range electric cars that spew NO exhaust of any type.
I thought this stuff was settled. Why rehash settled science?
Polishing a Turd.
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Can't in any way be a global warming skeptic and still get your NSF grants. Isn't that right, Dr. Shakun?
Puhlease.
CO2 is found in low (~300) parts per million.
Water vapor is found in low parts per hundred. Many thousands of times more frequent.
It also goes in and out of the air easily, primarily driven by temperature changes.
There is absolutely no way water vapor exhausted from engines could affect climate.
BTW, water vapor is a very large component of the exhaust gases from gas, diesel, etc. engines.
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