Study explains early warming of West Antarctica at end of last ice age
CORVALLIS, Ore. – West Antarctica began emerging from the last ice age about 22,000 years ago – well before other regions of Antarctica and the rest of the world, according to a team of scientists who analyzed a two-mile-long ice core, one of the deepest ever drilled in Antarctica.
Scientists say that changes in the amount of solar energy triggered the warming of West Antarctica and the subsequent release of carbon dioxide (CO2) from the Southern Ocean amplified the effect and resulted in warming on a global scale, eventually ending the ice age.
Results of the study were published this week in the journal Nature. The authors are all members of the West Antarctic Ice Sheet Divide project, which was funded by the National Science Foundation.
The study is significant because it adds to the growing body of scientific understanding about how the Earth emerges from an ice age. Edward Brook, an Oregon State University paleoclimatologist and co-author on the Nature study, said the key to this new discovery about West Antarctica resulted from analysis of the 3,405-meter ice core.
“This ice core is special because it came from a place in West Antarctica where the snowfall is very high and left an average of 20 inches of ice or more per year to study,” said Brook, a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Not only did it allow us to provide more accurate dating because we can count the layers, it gave us a ton more data – and those data clearly show an earlier warming of the region than was previously thought.”
Previous studies have pointed to changes in the Earth’s orbit around the sun as the initial trigger in deglaciation during the last ice age. An increase in the intensity of summer sunlight in the northern hemisphere melted ice sheets in Canada and Europe starting at about 20,000 years ago and is believed to have triggered warming elsewhere on the globe.
It previously was thought that Antarctica started its major warming a few thousand years later, at about 18,000 years before present. However, the new study shows that at least part of Antarctica started to warm 2,000 to 4,000 years before this. The authors hypothesize that changes in the total amount of sunlight in Antarctica and melt-back of sea ice caused early warming at this coastal site – warming that is not recorded by ice cores in the interior of the continent.
“The site of the core is near the coast and it conceivably feels the coastal influence much more so than the inland sites where most of the high-elevation East Antarctic cores have been drilled,” Brook said. “As the sunlight increased, it reduced the amount of sea ice in the Southern Ocean and warmed West Antarctica. The subsequent rise of CO2 then escalated the process on a global scale.”
“What is new here is our observation that West Antarctica did not wait for a cue from the Northern Hemisphere before it began warming,” Brook said, “What hasn’t changed is that the initial warming and melting of the ice sheets triggered the release of CO2 from the oceans, which accelerated the demise of the ice age.”
Brook said the recent increase in CO2 via human causes is also warming the planet, “but much more rapidly.”
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There are several papers on black carbon concentrations from ice cores. They show that during periods of warming BC increases, and during periods of cooling BC declines, and this IMO is the extra, over Milankovich Cycles that drives glacial to inter-glacial transitions. Interestingly this effect shows up in the LIA.
The six ice core samples from 750 B.P. to 100 B.P., the Little Ice Age,
had a mean black carbon concentration of 0.6 ug/kg, – a level that very likely reflects a
reduction in local biomass burning as well as reduction in forest fire activity that would
supply black carbon for long distance transport.
http://oceanography.dal.ca/publications/thesis/files/Wu.pdf
So, if the increased insolation caused a rise in the CO2 levels which, in turn, amplified the warming and caused the end of the Ice Age, what triggered the beginning of the Ice Age, because obviously the increased CO2 in the atmosphere would have prevented the decreased insolation from triggering a cooling.
So Antarctic warming was 2,000 to 4,000 years ahead of Artic melting and making CO2 levels rise.
This would mean that in spite of the rising of CO2 levels it took 2,000 to 4.000 years for the Arctic to start melting. Somehow that doesn’t sound very alarming to me.
Global climate shifts from warming to cooling at the highest CO2 concentrations and from cooling to warming at the lowest CO2 concentrations, if there’s a correlation between CO2 and T.
So CO2 follows temperature
So more evidence ties in with the Dome Law ice-cores.
So temperature changes take millennia to spread over the globe, historically.
There’s lots of curiosity here.
Not much of it alarming.
And not much of it proven to be related to the Sun.
In reality, hydrothermal/volcanic activity was probably the real cause of these early temperature rises – if indeed they occurred.
The prevailing wind in West Antarctica is from the north west from the area around Deception Island, an area of irregular strong volcanic activity.
Too much merde du taureau to contemplate this early in the day.
” JimS says:
August 14, 2013 at 4:36 pm
The last glaciation period ended because the earth’s eccentricity was at its peak, as was its obliquity, and the precession of the earth made it receive the maximum solar input to the northern hemisphere in the summer.”
Thank you. This cyclic pattern of ice ages and the Earth’s wobbling tilt have been known for some time. Now these anti-science alarmists MUST link CO2 to every historically known and verified event, or else be damned by them as their CAGW hypothesis fails to explain so many historical events.
I think they put their CO2 increase number , which was probably correct, into a GCM and got a big temperature increase.
From that they guessed the rest i.e. the melting of all that ice.
Still wrong though, as the GCM they used is like all the rest i.e. not fit for purpose.
Nice try though.
jchang @ur momisugly 14 Aug 2.21 pm,
Thanks for the link to the BBC doco. Seems the scientists were very much interested in the sun in those days. Since then they have been trying to forget that the sun actually exists. Doesn’t fit the CO2 meme obviously.
“ferd berple says:
August 14, 2013 at 4:43 pm
ferd berple says:
August 14, 2013 at 4:04 pm
this is why the atmosphere cools with altitude. otherwise it would be isothermal
================
this process would continue except that vertical circulation kicks in to limit the drop in temperature to the lapse rate – which is governed by gravity. objects can only fall so fast, so the conversion of PE to KE and thus temp/altitude is bound to gravity, moderated by the phase change of water.”
Correct, as I have tried to explain exhaustively on previous occasions both here and elsewhere.
The decline in pressure with height creates the lapse rate and convection maintains the lapse rate. If one takes the sum of all convection from surface to space it will always be just sufficient to maintain the ‘ideal’ lapse rate set by mass, gravity and insolation.
The most basic thermostat is the change of KE to PE and back again as the amount of convection changes.
The surface temperature will only change if the proportion of ToA insolation reaching the surface changes which is where cloudiness and albedo come in. I have shown how solar variations could change cloudiness and albedo by shifting the entire global air circulation latitudinally.
CO2 is only along for the ride and any net effect from that CO2 (whether warming or cooling) is simply negated by a miniscule circulation change that is lost in the noise of similar shifts caused by sun and oceans.
http://www.newclimatemodel.com/new-climate-model/
The problem is that the whole discussion is pointless when you interpret the proxies incorrectly. Every now and then it is remarked that isotopes in precipitation have more correlation with precipitation rate than with temperature. Michel Helsen’s PhD thesis for instance and also:
http://journals.ametsoc.org/doi/abs/10.1175/JCLI4027.1
“The spatial isotope–temperature relation varies strongly, which indicates that this widely used relation is not applicable to all sites and temporal scales.”
I have pointed out before that isotopes measure dewpoint, not temperature:
https://dl.dropboxusercontent.com/u/22026080/non-calor-sed-umor.pdf
I believe that the CO2 claim is the code key to trigger more research funds.
Do schools teach people to think anymore vs to just repeat propaganda?
After so many reports of runaway global warming manifesting exclusively in West Antarctica, although often concentrated in the Antarctic Peninsula, I’m surprised there was still ice at least two miles thick to drill. Are they sure they didn’t start going sideways?
Article writer: “…two-mile-long ice core…” “…of the 3,405-meter ice core.”
Professor Brook: “…20 inches of ice or more per year…” “…gave us a ton more data…”
Gee, I hope no one was expecting the US to go metric anytime soon, if ever, if even an esteemed Oregon State University paleoclimatologist shuns using metric in public statements.
What would have been so wrong with the OSU PR department sticking with metric in their press release? Don’t they realize “nearly three and a half kilometers long” sound much more impressive than simply “two miles”?
Don’t they realize the key to adoption is utilization? Besides, metric can sound good. At least half the US population would agree “It’s ten centimeters” sounds much better than “It’s four inches.”
Edim says: August 14, 2013 at 11:21 pm – “Global climate shifts from warming to cooling at the highest CO2 concentrations and from cooling to warming at the lowest CO2 concentrations, if there’s a correlation between CO2 and T.”
SamC says “Yes”, there is a correlation. It is called Henry’s Law.
SamC, I agree in general that there must be a correlation, but evidence is somewhat inconclusive. The most reliable evidence is the MLO data (I don’t find gas concentrations from ice cores valid) and it shows a correlation between change in CO2 and T. That means constant (annualy averaged) temperatures cause change in CO2, in other words the temperature doesn’t need to change at all for CO2 to change. IMO, the most plausible explanation is that the seasonal temperature cycle is causing change in CO2, by acting as a ‘reciprocating CO2 pump’, which is temperature dependent (dCO2 = f(T)).
My original point is that if one accepts the correlation between CO2 and T (at any timescale), one also must accept that climate shifts from warming to cooling at the highest ‘CO2 forcing and vice versa, at the timescale.
So, once again, CO2 chases the initial warming, and the scientist still claim it was CO2 all along.
What the hell is wrong with these people?
Milankovitch effects cancel between hemispheres and over the course of a year. There is no net effect on a global scale and a yearly time frame. In order to work at all they must be amplified by asymmetry like the concentration of continents in the Northern Hemisphere.
The highest correlation between Milankovitch insolation and glacial/interglacial transition is for sixty degree latitude Northern Hemisphere insolation. Here they abandon this in favor of lower correlation Southern Hemisphere insolation in order to fabricate a role for CO2.
and the precession of the earth made it receive the maximum solar input to the northern hemisphere in the summer.”
So why did the SH warm faster than the north ? Outgassing from larger, warmer land mass and the North Pac and N.Atlantic with higher radiation would surely have warmed the north pole quicker particular if polar amplication by CO² is correct.
MattN says:
August 15, 2013 at 6:32 am
So, once again, CO2 chases the initial warming, and the scientist still claim it was CO2 all along.
What the hell is wrong with these people?
MONEY !!!!
“Scientists say that changes in the amount of solar energy triggered the warming of West Antarctica and the subsequent release of plankton farts from the Southern Ocean amplified the effect and resulted in warming on a global scale, eventually ending the ice age.”
This makes just as much sense and is just as likely just as replicable. Send me my grant money!
So CO2 not only brings on the inter-glacial periods, with its blowtorch effect, but every time the CO2 levels reach a maximum we get glaciers…and this passes for an explanation of cause and effect.
@Stephen Fisher Richards
The first paragraph of the article says it all:
“West Antarctica began emerging from the last ice age about 22,000 years ago – well before other regions of Antarctica and the rest of the world, according to a team of scientists who analyzed a two-mile-long ice core, one of the deepest ever drilled in Antarctica.”
This seems to be an accurate account due to the Milankovitch Cycles, with some modifying remarks
The precession of the earth, 22,000 years ago, would be right about where we are now in that for the summer of the Southern Hemisphere would be wherein the earth was closer to the sun according to eccentricity. The tilt or obliquity would be around where we are now too. Therefore, it stands to reason that the SH would be receiving more solar energy than the NH where and when it counts.
The big HOWEVER is this though: 22,000 years ago, the earth was in the farthest reaches of its glaciation cycle. During these long glaciation periods that last from 85,000 to 90,000 years, the end of these cycles are the coldest parts. The preliminaries for our current interglacial period did not commence until about 14,500 years ago when the Bolling Oscillation drove global temperatures up by 12 C in one century. The actual Holocene did not really start until 11,500 years ago when the final drive to warming occurred after a few “cooling” setbacks after Bolling.
So this paper is really dealing with a minor warming period that occurred during the last glaciation period and not the beginning of our current interglacial period. I am surprised that the “scientists” who wrote this paper did not understand this for 22,000 years ago, the earth was not “emerging” from the “last ice age.”
Ian W says:
August 14, 2013 at 3:25 pm
Nitrogen and Oxygen are non-radiative gases – warm them up and they stay warm and do not radiate infrared. Add some CO2 and the CO2 warmed by collision – radiates infrared cooling the Nitrogen Oxygen mixture. For some reason this tropospheric cooling effect is disregarded (although it is discussed as cooling the stratosphere). CO2 radiating atmospheric heat does not appear in any of the AGW Mickey Mouse diagrams which only consider the absorption of surface radiation. It is probable that the CO2 radiative cooling effect may be equal or greater than heating by the absorption of infrared from the surface.
Has anyone actually done any experiments in this area?
I’ve brought this point up several times in the last 3 years and gotten no logical responses (as have others). I’m not sure how one would measure the cooling effect of increased CO2 in the atmosphere and separate it from the GHE. I suppose if one knew the total number of energy transitions (both radiation and kinetic), an estimate could be made.