The question of “which comes first, the temperature or the CO2 rise?” has been much like the proverbial “which came first, the chicken or the egg?” question. This seems to settle it – temperature came first, followed by an increase in CO2 outgassing from the ocean surrounding Antarctica.
“Our analyses of ice cores from the ice sheet in Antarctica shows that the concentration of CO2 in the atmosphere follows the rise in Antarctic temperatures very closely and is staggered by a few hundred years at most,” – Sune Olander Rasmussen
From the University of Copenhagen – Rise in temperatures and CO2 follow each other closely in climate change
The greatest climate change the world has seen in the last 100,000 years was the transition from the ice age to the warm interglacial period. New research from the Niels Bohr Institute at the University of Copenhagen indicates that, contrary to previous opinion, the rise in temperature and the rise in the atmospheric CO2 follow each other closely in terms of time. The results have been published in the scientific journal, Climate of the Past.
In the warmer climate the atmospheric content of CO2 is naturally higher. The gas CO2 (carbon dioxide) is a green-house gas that absorbs heat radiation from the Earth and thus keeps the Earth warm. In the shift between ice ages and interglacial periods the atmospheric content of CO2 helps to intensify the natural climate variations.
It had previously been thought that as the temperature began to rise at the end of the ice age approximately 19,000 years ago, an increase in the amount of CO2 in the atmosphere followed with a delay of up to 1,000 years.
“Our analyses of ice cores from the ice sheet in Antarctica shows that the concentration of CO2 in the atmosphere follows the rise in Antarctic temperatures very closely and is staggered by a few hundred years at most,” explains Sune Olander Rasmussen, Associate Professor and centre coordinator at the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.
Law Dome in Antarctica.
Deep-sea’s important role
The research, which was carried out in collaboration with researchers from the University of Tasmania in Australia, is based on measurements of ice cores from five boreholes through the ice sheet in Antarctica. The ice sheet is formed by snow that doesn’t melt, but remains year after year and is gradually compressed into kilometers thick ice. During the compression, air is trapped between the snowflakes and as a result the ice contains tiny samples of ancient atmospheres. The composition of the ice also shows what the temperature was when the snow fell, so the ice is an archive of past climate and atmospheric composition.
“The ice cores show a nearly synchronous relationship between the temperature in Antarctica and the atmospheric content of CO2, and this suggests that it is the processes in the deep-sea around Antarctica that play an important role in the CO2 increase,” explains Sune Olander Rasmussen.
He explains that one of the theories is that when Antarctica warms up, there will be stronger winds over the Southern Ocean and the winds pump more water up from the deep bottom layers in the ocean where there is a high content of CO2 from all of the small organisms that die and fall down to the sea floor and rot. When strong winds blow over the Southern Ocean, the ocean circulation brings more of the CO2-rich bottom water up to the surface and a portion of this CO2 is released into the atmosphere. This process links temperature and CO2 together and the new results suggest that the linking is closer and happens faster than previously believed.
Climatic impact
The global temperature changed naturally because of the changing solar radiation caused by variations in the Earth’s orbit around the Sun, the Earth’s tilt and the orientation of the Earth’s axis. These are called the Milankowitch cycles and occur in periods of approximately 100,000, 42,000, and 22,000 years. These are the cycles that cause the Earth’s climate to shift between long ice ages of approximately 100,000 years and warm interglacial periods, typically 10,000 – 15,000 years. The natural warming of the climate was intensified by the increased amount of CO2 in the atmosphere.
“What we are observing in the present day is the mankind has caused the CO2 content in the atmosphere to rise as much in just 150 years as it rose over 8,000 years during the transition from the last ice age to the current interglacial period and that can bring the Earth’s climate out of balance,” explains Sune Olander Rasmussen adding “That is why it is even more important that we have a good grip on which processes caused the climate of the past to change, because the same processes may operate in addition to the anthropogenic changes we see today. In this way the climate of the past helps us to understand how the various parts of the climate systems interact and what we can expect in the future.”
Tightened constraints on the time-lag between Antarctic temperature and CO2 during the last deglaciation
J. B. Pedro1,2, S. O. Rasmussen3, and T. D. van Ommen2,4
1Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania, Australia
2Institute of Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
3Centre for Ice and Climate, University of Copenhagen, Copenhagen, Denmark
4Australian Antarctic Division, Kingston, Tasmania, Australia
Abstract. Antarctic ice cores provide clear evidence of a close coupling between variations in Antarctic temperature and the atmospheric concentration of CO2 during the glacial/interglacial cycles of at least the past 800-thousand years. Precise information on the relative timing of the temperature and CO2 changes can assist in refining our understanding of the physical processes involved in this coupling. Here, we focus on the last deglaciation, 19 000 to 11 000 yr before present, during which CO2 concentrations increased by ~80 parts per million by volume and Antarctic temperature increased by ~10 °C. Utilising a recently developed proxy for regional Antarctic temperature, derived from five near-coastal ice cores and two ice core CO2 records with high dating precision, we show that the increase in CO2 likely lagged the increase in regional Antarctic temperature by less than 400 yr and that even a short lead of CO2 over temperature cannot be excluded. This result, consistent for both CO2 records, implies a faster coupling between temperature and CO2 than previous estimates, which had permitted up to millennial-scale lags.
Final Revised Paper (PDF, 463 KB) Discussion Paper (CPD)
Citation: Pedro, J. B., Rasmussen, S. O., and van Ommen, T. D.: Tightened constraints on the time-lag between Antarctic temperature and CO2 during the last deglaciation, Clim. Past, 8, 1213-1221, doi:10.5194/cp-8-1213-2012, 2012.
I’ve been following links here, beng, and commenting on them. As no one has addressed my links or even my central point, you can understand that I don’t want to search gogle scholar for a paper by Roe without the publication date, title or anything else that might narrow down the search.
But perhaps as no one has gainsaid my argument on lag/lead, then I might hope that next time a dozen commenters make the same illogical case, the people who have been replying to me will leap in and correct them.
Jim,
The mistake in thinking here is to imagine that CO2 is the only driver of climate. If orbital variations are the lead forcing for ice age shifts, then by definition other processes wil lag. We’re talking about a cooling process that happens slowly over tens of thousands of years. A < 1k year lag in CO2 is not an impediment to it playing a part in glacial transitions.
Much of the discussion on transition to stadial is based on Vostok ice core data. I have yet to come across a paper that addresses a multi-regional analysis (a la Shakun).
barry says:
“The mistake in thinking here is to imagine that CO2 is
the onlya driver of climate.”There. Fixed it for you.
[CO2 is a GHG, but it does not ‘drive the climate’.]
Just a ley person question. Why would the uplift of temperature be the same as the downshift in temperature. If there is a lag in co2 and it apparently helps the temperature to go up further, then why wouldnt there be a lag in cooling along with the lag in co2 dropping.
Shouldnt the drop in temperature be slower than the rise. This is assuming they even know what caused the temperature rise in the first place and the drop being from said driver going away.
It seems that a lot of people here has problems with the notion that CO2 lags temperature. That doesn’t prove that CO2 has no effect on temperature, it can be both. The only point is that the back and forth feedback factors can’t be high, as that would give a runaway effect, which is not observed at all.
The main problem, as already mentioned by others, is that there is a huge overlap of several thousands of years between temperature and CO2 levels, no matter if the lag of CO2 is 200 or 600 years. That allows the climate modellers to implement a relative huge positive feedback from CO2 on temperature. But the other way round is more difficult to explain:
At the end of the previous (warmer) interglacial, the Eemian, CO2 levels remained high for thousands of years, while temperatures already reached a new minimum (and ice sheet buildup reached a new maximum), before starting to decline. The subsequent drop of 40 ppmv didn’t have a measurable effect on temperature. That points to a small effect of CO2 on temperature:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/eemian.gif
Where two different methods were used for interpreting the temperature proxy (dD) and the d18O in N2O of the gas phase proxy was used to interprete ice sheet buildup, all measured in the Vostok ice core.
Jim Masterson says:
July 26, 2012 at 10:32 am
Now that the ice core record is proving problematical in the area of CO2/temperature timing, the ice cores have to be discredited. I guess CO2 isn’t “well-mixed” after all.
Does this mean that the leaf stoma count proxy is now more accurate? You can’t have it both ways.
The problem with ice cores is not the accuracy of the CO2 measurements: these are accurate to +/-1.2 ppmv (1 sigma) in the same ice core and up to +/- 5 ppmv for several cores taken at different places with a huge variety in accumulation rate, average temperature, etc… The real problems are that the CO2 levels measured at a certain depth are the average of several years to several centuries, depending of the accumulation rate and that the age of the average CO2 levels measured lags the age of the ice layer where these are found from a few decades to several millennia. The cause for both is that the pores between the densifying snow are still open for many years, exchanging air and thus CO2 with the open air above it, slower and slower, until the pores are too small to give any exchange anymore.
Thus where the slow closing of the pores and bubbles give a lag, the estimates for the amount of lag in average age and thus the estimates for a real lag in CO2 after temperature (the latter is measured as proxy in the oxygen or deuterium isotopes in the ice layer) is a huge challenge.
Thus the CO2 levels measured in ice are quite reliable, but averaged over a short (8 years for the past 150 years for 2 out of 3 Law Dome ice cores) to very long period (550-600 years for the Vostok and Dome C resp. 420 and 800 kyr).
Stomata (index) data have their own problems: they reflect the average CO2 level of the previous growing season over the regional area in the main wind direction over land where the plants grow. That gives already a positive bias, which can be accounted for by calibrating them over the past century against… ice cores and direct measurements. But that is no guarantee that the bias didn’t change over the centuries as result of huge changes in landscape (natural or human driven) in the main wind direction, even a change in main wind direction over specific periods of time…
Peridot says:
July 24, 2012 at 8:07 am
Help!
I wish I could get a logical answer to questions I have asked before with no result. I am a very interested lay person who reads widely and can see when things defy common sense and logic.
As natural emissions of CO2 vary greatly either seasonally (Autunmn in the Northern Hemisphere) or randomly (volcano & vents) and this ‘extra’ CO2 does not end up joining the residual CO2 8 miles up or so (if it did there would hugely more there) why would our paltry emissions defy gravity and do that?
I hope that I can help somewhat with your questions…
Natural emissions do vary hugely with the seasons, but don’t vary that much over the years:
For an average global temperature change over the seasons of about 1°C, a lot of CO2 is exchanged between the oceans and the atmosphere (about 50 GtC as CO2) and the biosphere and the atmosphere (about 60 GtC). Besides that, there is a near continuous exchange of CO2 (about 40 GtC) between the deep oceans and the atmosphere: out of the upwelling in the warm Pacific and down into the NE Atlantic and returning via the THC through the deep oceans.
The continous exchange has no effect on the CO2 levels in the atmosphere, as long as there is an equilibrium between the sinks and sources. The seasonal exchanges also have a limited effect on CO2 levels, as ocean releases/uptake and biosphere uptake/release are working countercurrent. The net global effect is about 5 ppmv/°C, where the largest effect is from the spring uptake of land vegetation in the mid-latitudes of the NH. Besides that, at the end of the year, the seasonal exchanges cancel each other out, except for any difference in in/outflows over that year.
Volcanoes and volcanic vents over land are a minor source (estimates are 1% of human emissions). Even a huge VEI 5 volcanic explosion like the Pinatubo in 1992, does show a drop in CO2 increase rate, as the cooling as result of the ash cloud absorbed more CO2 (in the oceans) than the volcano released.
Underwater volcanoes are far more unknown, but most of that CO2 is dissolved in the already huge mass of CO2 of the deep ocean waters.
The human emissions today are about 8 GtC/year. The measured increase in the atmosphere is about halve that, with a variability of the same order, halve the human emissions. Thus the year by year natural variability is rather small and mainly temperature related:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/dco2_em.jpg
Nature was a net sink, at least over the past 50 years.
Thus while the human emissions are rather small, they are the main cause of the increase in the atmosphere at least over the past 50 years, with a small contribution of the increase in temperature since the LIA. See further:
http://www.ferdinand-engelbeen.be/klimaat/co2_measurements.html#The_mass_balance
A note on the mixing of CO2 into the rest of the atmosphere: Except nearby huge point sources and the first few hundred meters over land, CO2 is well mixed in 95% of the atmosphere, but that takes time. The seasonal changes give a 20% exchange of all CO2 in the atmosphere. The regional changes need days to weeks to distribute within one latitude/altitude layer, weeks to months between altitudes and latidudes of the same hemisphere and months to a few years between the hemispheres.
CO2 is heavier than air, but wind and convection mixes it in and brings it everywhere and Brownian motion keeps it mixed…
barry says:
July 25, 2012 at 6:33 pm
Gail,
…. There’s no need to isolate Milankovitch theory, as it is part and parcel of the suite of processes that cause glacial changes. You seem to be positing opposing viewpoints where there is no opposition.
The objections to Shakun et al and the current paper are based on muddled thinking and misunderstandings. It’s not worth trawling through all the junk there, but let’s take the first objection from the first WUWT article you linked.
If rebutting Shakun relies on denying the greenhouse effect of CO2, then it’s useless taking the discussion seriously….
__________________________________
No it does not rely on “..denying the greenhouse effect of CO2…” and I am not going to recap it here.
As far as water goes, when you take into account 70% of the surface of the earth is water, a large chunk of high energy TSI penetrates the oceans and to a depth as great as 100 meters Then add in the heat capacity of the oceans is much larger than the atmosphere, and more importantly CO2 is more soluble in cold water than in hot, I am afraid that trying to make CO2 the Control Knob of the climate is really laughable.
Then you add in CO2 is 200 – 400 ppm while H2O varies up to 4%. The latent heat from water turning into vapor and back into rain and snow, the albedo from clouds, snow and ice. and the fact that rainforest (80 – 90% humidity) Have much less temperature swing and a lower over all temperature than an equivelant desert, you really lost the battle. link
Is CO2 a “Green house gas? Sure but water in all its variations beats CO2 to death when it comes to its effect on climate. Also there is no way you can over look the influence of the sun. Only by stating that TSI must be held constant and NOT looking at the variations in the wavelengths of TSI especially the variation in the wavelengths above visible light (up to 6%), the same wavelength that most effect the oceans, could the CAGW hoax hope to be advanced.
barry says:
July 26, 2012 at 8:06 am
beng,
…I doubt the Roe paper is going to change the picture very much, but please link to it if you think it’s really worth pursuing.
_______________________________
It was right there at the top of the blog linked to.
Try this PDF/a>
Jim Masterson says: @ur momisugly July 26, 2012 at 12:45 pm
…..Even the IPCC tends to agree, because it gives CO2 the GWP of 1 (by definition). All other GHGs have a higher GWP. The IPCC even leaves out two major GHGs–water vapor and ozone. Try as you might, you won’t find a GWP value for either gas–the IPCC has conveniently excluded them in their definition of GWP.
__________________________________________
Yeah that is the BIG CLUE that the whole thing is really a hoax.
This is the other BIG CLUE when the true motives come out.
From NoTricksZone
You just can not separate UN politics from CAGW.
how many times does the cause and effect have to be proven!
gav says:
July 27, 2012 at 6:42 pm
how many times does the cause and effect have to be proven!
That the CO2 levels lag the temperature changes doesn’t prove that CO2 has no influence on temperature, only that the influence can’t be extreme, as that would give a runaway effect. I have made a graph that shows the difference between CO2 having no effect on temperature and CO2 giving a 10% increase in temperature as a positive feedback. In both cases with the same lag for CO2. In the case of a positive feedback, both temperature and CO2 levels increase with 21% over time:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/feedback.jpg
>>
FerdiEgb says:
July 27, 2012 at 12:24 pm
The problem with ice cores is not the accuracy of the CO2 measurements: these are accurate to +/-1.2 ppmv (1 sigma) in the same ice core and up to +/- 5 ppmv for several cores taken at different places with a huge variety in accumulation rate, average temperature, etc…
<<
After taking measurements, it would be nice if we could look in the back of the book and find the correct answer. Then we could determine the accuracy of our measurements. The Universe, unfortunately, doesn’t provide the answers in the back of the book. What you should say is that the CO2 measurements have a “precision” of ±1.2 ppmv (I’m surprised it’s not far better). Of course, measuring the gas concentrations in a test tube is the final step in a long series of steps that may upset that precision. (See, for example, the criticism of Dr. Zbigniew Jaworowski.)
The Entropic man pointed to a reference where local CO2 levels may not represent the global average. As the first step in the ice core process was that CO2 had to be well-mixed in the atmosphere, this would affect the entire ice core process (from initial gas capture by the snow/ice to final measurement).
So my question should become clearer since accuracy is a subjective vice objective call. Does this make leaf stoma count more accurate? The number of stomata on a leaf compared to CO2 levels is calibrated to a precision of about ±30 ppmv. The actual overall precision of the ice core measurements is unknown. As said previously, only the last step has a precision of ±1.2 ppmv.
Jim
Jim Masterson says:
July 31, 2012 at 5:48 pm
Sorry for the late reply…
The actual overall precision of the ice core measurements is unknown. As said previously, only the last step has a precision of ±1.2 ppmv
The overall accuracy of the ice core measurements were tested for three Law Dome ice cores, as stated in the 1996 work of Etheridge e.a. The three ice cores had overlapping dates for the average age in CO2 content of the bubbles in the ice, the CO2 measured in still open pores at closing depth (independently measured directly from the pore gas and from the ice core bubbles with the same GC) and an overlap of ~20 years with the direct measurements at the South Pole.
All multiple measurements for the same average gas age depth in the different cores and the South Pole measurements were within 1.2 ppmv (one sigma):
http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_sp_co2.jpg
Replication is the scientific explanation of a law or fact of science. In other words, if two or more independant parties replicate the experiment and get the same conclusions, then that theory can be proven to be a fact or law of the scientific method. I could be wrong, but that is the way I understand it.
Wow! No, waaayyy too squishy.
A “law” requires prolonged, probing, competent, ingenious attempts to replicate/falsify — which fail to defeat the proposed phrasing. I.e., everyone has to pretty much exhaust their alternatives and attempts to disprove, and give up for a while. But it can still happen that later on someone finds a better, more inclusive and general formulation which permits a distinguishing test to be done, which the supposed “law” fails.