Study: ‘ Greenland ice sheet is not as sensitive to temperature increases and to ice melting and running out to sea in warm climate periods ‘.
From the University of Copenhagen
Greenland ice cores reveal warm climate of the past
In the period between 130,000 and 115,000 years ago, Earth’s climate was warmer than today. But how much warmer was it and what did the warming do to global sea levels? – as we face global warming in the future, the answer to these questions is becoming very important. New research from the NEEM ice core drilling project in Greenland shows that the period was warmer than previously thought. The international research project is led by researchers from the Niels Bohr Institute and the very important results are published in the prestigious scientific journal, Nature.
In the last millions years the Earth’s climate has alternated between ice ages lasting about 100,000 years and interglacial periods of 10,000 to 15,000 years. The new results from the NEEM ice core drilling project in northwest Greenland, led by the Niels Bohr Institute at the University of Copenhagen show that the climate in Greenland was around 8 degrees C warmer than today during the last interglacial period, the Eemian period, 130,000 to 115,000 thousand years ago.
“Even though the warm Eemian period was a period when the oceans were four to eight meters higher than today, the ice sheet in northwest Greenland was only a few hundred meters lower than the current level, which indicates that the contribution from the Greenland ice sheet was less than half the total sea-level rise during that period,” says Dorthe Dahl-Jensen, Professor at the Niels Bohr Institute, University of Copenhagen, and leader of the NEEM-project.
Past reveals knowledge about the climate
The North Greenland Eemian Ice Drilling project or NEEM, led by the Niels Bohr Institute, is an international project with participants from 14 countries. After four years of deep drilling, the team has drilled ice cores through the more than 2.5 kilometer thick ice sheet. The ice is a stack of layer upon layer of annual snow fall which never melts away, and as the layers gradually sink, the snow is compresses into ice. This gives thousands of annual ice layers that, like tree rings, can tell us about variations in past climate from year to year.
The ice cores are examined in laboratories with a series of analyses that reveal past climate. The content of the heavy oxygen isotope O18 in the ice cores tells us about the temperature in clouds when the snow fell, and thus of the climate of the past. The air bubbles in the ice are also examined. The air bubbles are samples of the ancient atmosphere encased in the ice and they provide knowledge about the air composition of the atmosphere during past climates.
Past global warming
The researchers have obtained the first complete ice core record from the entire previous interglacial period, the Eemian, and with the detailed studies have been able to recreate the annual temperatures – almost 130,000 years back in time.
“It is a great achievement for science to collect and combine so many measurements on the ice core and reconstruct past climate history. The new findings show higher temperatures in northern Greenland during the Eemian than current climate models have estimated,” says Professor Dorthe Dahl-Jensen, Niels Bohr Institute.
Intense melting on the surface
During the warm Eemian period, there was intense surface melting that can be seen in the ice core as layers of refrozen meltwater. Meltwater from the surface had penetrated down into the underlying snow, where it once again froze into ice. Such surface melting has occurred very rarely in the last 5,000 years, but the team observed such a melting during the summer of 2012 when they were in Greenland.
“We were completely shocked by the warm surface temperatures at the NEEM camp in July 2012,” says Professor Dorthe Dahl-Jensen. “It was even raining and just like in the Eemian, the meltwater formed refrozen layers of ice under the surface. Although it was an extreme event the current warming over Greenland makes surface melting more likely and the warming that is predicted to occur over the next 50-100 years will potentially have Eemian-like climatic conditions,” she believes.
Good news and bad news
During the warm Eemian period there was increased melting at the edge of the ice sheet and the dynamic flow of the entire ice mass caused the ice sheet to lose mass and it was reduced in height. The ice mass was shrinking at a very high rate of 6 cm per year. But despite the warm temperatures, the ice sheet did not disappear and the research team estimates that the volume of the ice sheet was not reduced by more than 25 percent during the warmest 6,000 years of the Eemian.
“The good news from this study is that the Greenland ice sheet is not as sensitive to temperature increases and to ice melting and running out to sea in warm climate periods like the Eemian, as we thought” explains Dorthe Dahl-Jensen and adds that the bad news is that if Greenland’s ice did not disappear during the Eemian then Antarctica must be responsible for a significant portion of the 4-8 meter rise in sea levels that we know occurred during the Eemian.
This new knowledge about past warm climates may help to clarify what is in store for us now that we are facing a global warming.
Niels Bohr Institute: http://www.nbi.ku.dk/english/
Documentary films: http://www.nbi.ku.dk/english/sciencexplorer/earth_and_climate/
Steven Mosher says:
January 24, 2013 at 8:25 am
or here is another logic defying statement.
well, obviously the planets temperature can vary by 8 degrees due to natural forcing, therefore C02 can have no effect.
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get back to us when you have that signal and noise thing figured out
LazyTeenager says:
January 24, 2013 at 3:43 am
I am fairly certain that humans can survive. But modern civilization will not
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Eric Steig has a post on this same subject at RC that might be worth a look:
http://www.realclimate.org/index.php/archives/2013/01/the-greenland-melt/
It’s also interesting to look at the right-hand side of the climate graph. Expand that a bit and there appears to be several times in the last few thousand years where the temperature was noticeably higher than today. You don’t here the CAGW crowd talking about them either. It must be nice to have such an effective set of blinders.
The accepted science is that during the last interglacial there were hippos living on the Thames. Then how could there have been any year round ice on Greenland at all?
LazyTeenager says:
” Well some here claim that such high temperatures are not possible because clouds will rescue us. If it can get to +8C in Greenland it could easily get to +4C global average.
But it didn’t. It even got 10-14 degrees warmer in northeastern Siberia. In temperate Eurasia it was about 2-5 degrees warmer than now. Around the Mediterranean and in the Eurasian desert zone it was if anything slightly cooler than at present (but much wetter), and in the tropics it was slightly warmer than today, at most 1-2 degrees.
A similar pattern, but with generally slightly smaller changes in the southern hemisphere
“Looks like the “clouds will save us” theory goes in the trash can.”
My guess is that the clouds did save our ancestors.
tty says: “See my post of 12:23 AM. The whole Eemian part of the curve is shaky. At least they admit that the results are uncertain.”
Unlike certain Hockey-Schtick proponents who repeatedly state that the debate is over.
Lazy teenagers says:
” Well some here claim that such high temperatures are not possible because clouds will rescue us. If it can get to +8C in Greenland it could easily get to +4C global average.
But it didn’t. It even got 10-14 degrees warmer in northeastern Siberia. In temperate Eurasia it was about 2-5 degrees warmer than now. Around the Mediterranean and in the Eurasian desert zone it was if anything slightly cooler than at present (but much wetter), and in the tropics it was slightly warmer than today, at most 1-2 degrees.
A similar pattern, but with generally slightly smaller changes in the southern hemisphere
“Looks like the “clouds will save us” theory goes in the trash can.”
My guess is that the clouds did save our ancestors.
When our own written history, tells of wide ranging climate, geology agrees from what the rocks tell us, the idea that climate has been an unchanging constant until today and we and only we are the agents of change, is conceit and idiocy of the highest order.
The term of denier, applied to any who question, by the believers of this illogic is projection.
When one must deny history, present day evidence, so as to reinforce their faith, one is intimately familiar with denying reality.
Crosspatch is right these types are too deranged to be allowed any positions of authority.
Greenland is being used as the Big Stick to frighten the general population into submission and accept greater taxes and control. Most people here on WUWT are fairly relaxed about Greenland ice Armageddon. Greenland will be here when our great, great grandchildren are gone.
I have trouble fitting together these two parts of the puzzle. From their caption and text:
and
She’s saying we’ll see something like eight degrees warming in the next 50-100 years?
Hmmm …
w.
Comparing the watts of insolation at the moment that the previous interglacial decided to go down at 45 degrees to the insolation value we have today, on that graphic without better resolution the two numbers look pretty similar. Both about 425 W/m2 ?
Why not? Places like Canada, Russia / Siberia, northern Europe, the Antarctic Peninsula etc. would become more hospitable? No? Also bear in mind such changes would not take place overnight. Bear in mind also that the world population is estimated to stabilize this century AND begin to decline. Aging populations, such as in Japan, are another problem. I am reluctant to make prediction so only time will tell.
Population
http://www.economist.com/node/14744915
http://business.time.com/2012/12/04/birth-rate-plunges-during-recession/
http://www.economist.com/node/15959332
Steven Mosher says:
January 24, 2013 at 8:25 am
Fires have started by lightening, therefore arson cannot cause fires.
Did you perhaps mean ‘lightning’ (as in ‘a bolt of lightning’), Steve?
If not, your following statement should probably be ‘therefore arson can not cause weight loss’.
MtK
Parts of Greenland – and the Arctic region in general – have seen ~ +8-10C of warming in the past few years as a result of GHG forcing and associated ice-albedo feedback warming. The average global temperature during the Eemian climatic optimum is estimated to have been around +1C above the pre-industrial average. We are currently around +0.8C.
The warming during the Eemian interglacial was triggered by slight increases in insolation by our orbital configuration at the time. We are now seeing a similar level of warming in the Arctic due to GHG forcing and ice-albedo feedback..
The Eemian warm-up happened over many centuries and led to a 6-9m global sea-level rise. It is possible that we will see +2C of global warming in the next century and we’ll have to trust in the thermal inertia of the ice caps to prevent a similar outcome.
Folks relating this finding to the ‘hockey stick’ do know that the Eemian was farther back into the past than anything in the ‘hockey stick’ graph by a factor of roughly ten–don’t they?
Sorry, 100, not just 10…
Those were Ice Hippos; not regular ones!:]
Willis Eschenbach says:
January 24, 2013 at 12:24 pm
She’s saying we’ll see something like eight degrees warming in the next 50-100 years?
Hmmm …
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yep potentially……and there’s no one living in Miami
Thank you ‘Lazyteenager’ I did’t take the trouble to read the scale on the main graph properly.
I do not think they were hairy hippos! The interpretation of varves or layers of ice is very questionable especially at the bottom where the layers thin out. There must not have been any year round ice.
Can we just go with the fact that it has been warmer in the past and save my money?!?!? Is that too much to ask for? Really?
So here is the idea. All you greeny researchers out there just say,
“It was warmer in the past according to [tree rings, ice rings, clam shells, and the lady with the globe over there in the tent] and that because we know this, we can better understand what our fate will be when we all fry in hell here on Earth because of anthropogenic global [warming, weirding, catastrophies, colding, weather extremes, whatever word is currently hip].”
There. All done. Just copy and paste in any journal. You can have your scary scenario and I the tax payer just saved a bucket load of money.
Latitude says:
January 24, 2013 at 2:31 pm
Potentially? What on earth does that mean? Potentially, I could win the lottery tomorrow. On that basis, should I quit my job and buy leisure suits to make preparations for my newfound wealth?
I must confess … I grow tired of vague handwaving about “potentially” from folks like Dorthe Dahl-Jensen who are masquerading as scientists … when I want wild speculation on what might “potentially” happen, I’m perfectly capable of providing my own.
w.
LazyTeenager says:
January 24, 2013 at 3:51 am
The new results show that during the Eemian period 130,000 to 115,000 thousand years ago the climate in Greenland was around 8 degrees C warmer than today.
———–
Well some here claim that such high temperatures are not possible because clouds will rescue us. If it can get to +8C in Greenland it could easily get to +4C global average.
Looks like the “clouds will save us” theory goes in the trash can.
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No one here has claimed that higher temps are impossible. They have merely claimed, as this study shows, that we can have temps as high as we have, and much higher, through natural climatic processes within any interglacial.
Nor is there some claim that clouds will prevent higher temps, only that the feedbacks from water vapor are not as high as claimed.
We have no knowledge of why the Eemian temps were so much higher than during our Holocene, One thing should be obvious, however: water vapor feedback was not the source of that difference, since nothing has changed on that front, or we’d have suffered the same consequence in the Holocene.
And Steve Mosher, don’t be such a tool. It’s the AGW types who have claimed that it’s impossible to have warming such as we have now, without manmade GHGs being the driver. No one has ever claimed they can’t possibly be the driver, only that the claim of that they must be the driver is clearly nonsense. The fact that the Eemian was so much warmer, without any higher CO2 buildup, clearly indicates GHGs are not the only possible driver of warm interglacial periods like ours.
“Parts of Greenland – and the Arctic region in general – have seen ~ +8-10C of warming in the past few years as a result of GHG forcing and associated ice-albedo feedback warming.”
You are aware, I hope that Greenland was warmer in the 1930-40s than it has been recently, without GHG being at all involved in that. How do you explain that?
Your other numbers and logic are just as faulty.