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/
So when drilling anywhere in Greenland, did they ever hit bedrock (or solid ground)?
If not, that seems to imply that no matter how hot the past was, Greenland always had ice.
“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. ”
Wrong. no one says that is IMPOSSIBLE to have the warming we have now without GHGs.
The argument is entirely different
Steven Mosher says:
January 24, 2013 at 8:25 am
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.
Over the last half billion years or so there appear to be two principal stable temperatures – about 12 C and 22 C, according to this often quoted and quite simple graph. However these are likely related to continental configuration and may represent attractors with and without iced up poles.
What is striking in this ice core plot back to the Eemian is how unstable the glacial period is, with many sharp up-spikes in temperature. By contrast the interglacials have a much smoother temperature curve. We are fortunate to live in an interglacial period of relative climate stability – imagine living through a temperature spike of 5-8 C over just a century or two.
It is also unclear why the Younger Dryas is talked about as if it is something exceptional. It is not. It is simply one of several dozen similar spikes which characterise climate instability during glacial periods – albeit one of the largest spikes.
Finally there is a typo in the last sentence:
This new knowledge about past warm climates may help to clarify what is in store for us now that we are facing a global
warmingcooling .Fixed.
Steve, please stop being so obtuse. You know very well that one of the primary arguments of the AGW advocates is that our present warming has to be man-made, and that natural forces could not account for it. Even though, when pressed, they admit they don’t fully understand all the natural forces that go into climate, they will still claim our warming has to be anthropogenic. The example of the Eemian shows that natural forces really can produce higher temps even than ours at present. It doesn’t prove that GHGs play no role in today’s warming, but it does show that there’s no necessity in using them to explain our present climate trends.
What a frightening metric. Enjoy the good times now. They are nearly over. Even worse than the return of the continental ice will be the drop in sea level – that drop will foment an extinction event.
Steven Mosher says:
January 24, 2013 at 6:59 pm
Thanks, Mosh. I suspect the argument he is referring to is the argument involving climate models. It says that because climate models do poorly when you remove the anthropological forcings, this means the anthropological forcings must be causing the temperature changes. See the IPCC AR4 version of the argument here.
The clearest statement is from the IPCC TAR (emphasis mine):
That sounds a whole lot more like what he said than to what you said … I don’t doubt that, as you say, there is another argument out there that “is entirely different”. But the argument he’s talking about has definitely been made, and by the IPCC no less.
w.
PS—If I were a tool, I think I’d be a Leatherman …
Willis says: “The clearest statement is from the IPCC TAR…”
The discussion of Figure 9.5 in AR4 is pretty clear also:
“Figure 9.5 shows that simulations that incorporate anthropogenic forcings, including increasing greenhouse gas concentrations and the effects of aerosols, and that also incorporate natural external forcings provide a consistent explanation of the observed temperature record, whereas simulations that include only natural forcings do not simulate the warming observed over the last three decades.”
http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter9.pdf
Regards
Steven Mosher says:
January 24, 2013 at 6:59 pm
“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. ”
Wrong. no one says that is IMPOSSIBLE to have the warming we have now without GHGs.
The argument is entirely different
====================
When we do find our new energy source, which of course we will, what will become of the windmills?, will they fade into history again.
Or will the subsidies continue the blight of greed and corruption ?
It is of windmills, I ask.
How could polar bears survive +8 C? maybe by changing their fur color?
They did not and will not.
Two comments:
Mann’s hockey stick covered about the last 2,000 years; the first tick on the graph above is at 20,000 years. Do posters here have a problem understanding scale? Besides, the O18 measurements from last summer’s melt event were in the same ballpark as those during the Eemian. Kind of a sharp uptick there.
Warming then versus warming now. A comparison of apples and oranges is being made. Yes, under different orbital conditions and various other factors, it is possible to achieve the same level of warming as we are currently starting. No, under the current orbital conditions, etc. it is not possible to cause the level of warming we are seeing without the increase in CO2 levels we are causing. Bob and others are seriously confusing “not possible” ever, with “not possible” under current conditions. Brokenyogi was clearly talking about the past, with different background conditions, and Bob is clearly talking about the present.
(off topic) Just a comment to see if I’m still banned. (on topic) you are wrong (1st amendment), this so called eemian ice sheet was a product of God’s angels who in 4004BC used their superpowers to accidentally freeze the whole atmosphere. Now, because they stood on the ‘then’ equator, the air flows converged over the drill site. producing a 2 meter wide column of ice, 300 m in height. Later in the same day God thought that was a good idea to fool the people. So, he built the so-called ice ages to the antarctica. that was originally planned to be the place for Eden. Then God created Adam, and put him on the continent of Mu, located in the Indian Ocean. The Eden had to be erased for the sins of Adam and then, after about 5950 years, you were born.
Thanks, Willis and Bob, for filling in the details of what I assumed Mosher must already know, but is pretending not to.
SasjaL says:
January 24, 2013 at 2:25 am
“This is always true, just as Michael E. Mann’s* prophecies/warnings in the 1970s that we are approaching a new ice age. It depends solely on what part of the glacial cycle we are studying, but with the immediate future in mind, M.E. Mann’s* (previous) claim is more relevant.”
Uh, Mann was 5 years old in 1970 and I seriously doubt he was making climate predictions.
brokenyogi says:
January 24, 2013 at 7:28 pm
“The example of the Eemian shows that natural forces really can produce higher temps even than ours at present. It doesn’t prove that GHGs play no role in today’s warming, but it does show that there’s no necessity in using them to explain our present climate trends.”
Unless that’s exactly what’s happening, no?
The polar bears did not survive.
In general, a few commenters need the CO2 forcing argument to heighten the feelings of guilt in the young and foolish. Without the willing consent of such folks they have lost their hope of leading all of us to a better way.
~~~~~~~
And a specific:
banninations continuament?
“. . . (1st amendment) ”
I assume this refers to the USA Bill of Rights. I’ll guess you don’t know what rights that amendment gives you. Regarding the privilege of commenting on blogs, the first amendment has no relevance.
J.Seifert says:
January 24, 2013 at 8:05 pm
Laurence Crossen says:
January 25, 2013 at 1:36 am
Yes, it’s well known that they went extinct in the Eemian, a hundred thousand years ago …
w.
I’m surprised you even took me up on it! It is not well known, but I am confident that is what happened. But I am not an AGWer! I know AGW is pure pseudoscience.
brokenyogi says:
January 24, 2013 at 11:25 pm
Brokenyogi, assuming that you can tell what other people know is a very foolish enterprise. You haven’t a clue what Mosh knows, or I know, or anyone else knows.
But insulting people by claiming that they are pretending not to know what you can tell, by way of your spidey sense, that they already know?
That’s just nasty and unpleasant. You don’t know what Mosh knows, only Mosh knows that, and all your ugly claim does is to make you look much, much worse than him.
w.
Willis Eschenbach says: January 25, 2013 at 10:30 am
“… You haven’t a clue what Mosh knows, or I know, or anyone else knows….”
Theoretically correct, I guess. But a pedantic, politically correct Willis … who’d a thunk it?
If Mosher says he didn’t know of this particular line I’d eat my hat…if I had one.
“Natural forcing alone cannot explain the global warming over the last 50 years.”
Thanks, Mark. Mosher likely knows of the line, he’s widely read. But he may have been thinking of something different, or just had a senior moment, or assumed people were discussing some other aspect, who knows. In any case, speculation on his motives and inner mental workings is something extra to your underlying point, which was scientific rather than personal.
Regards,
w.
J.Seifert says:
January 24, 2013 at 8:05 pm
How could polar bears survive +8 C? maybe by changing their fur color?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
They are ‘Albino’ grizzlies and are still able to produce viable crosses http://studentsonice.com/blog/general/polar-bear-plus-grizzly-equals/
This means genetically they are not that far removed from grizzlies (brown bears)
In response to:
“J.Seifert says:
January 24, 2013 at 8:05 pm
How could polar bears survive +8 C? maybe by changing their fur color?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
They are ‘Albino’ grizzlies and are still able to produce viable crosses http://studentsonice.com/blog/general/polar-bear-plus-grizzly-equals/
This means genetically they are not that far removed from grizzlies (brown bears)”
Solution: They re-evolve whenever it gets cold enough.
Willis,
Thanks for the snark, but really, Mosher is a regular reader and commentator on this blog, he blogs on his own about climate stuff, he’s clearly well read, and probably much better so than I am. So I think it would be insulting for me not to presume that he knows about the AR4 and the kinds of arguments they make. It was nice of you to post those excerpts, but I’m sure in no way necessary to Steve’s education. I notice in a latter post that even you say he must know this stuff already. So what’s the beef? That I actually called him out on it?
Personally, I think it’s your comments to me that were condescending, insulting, and pedantic. Especially since you even agree with me about what Mosher knows about climate science. Fortunately, I don’t much care when people insult me, if they at least can argue intelligently about the underlying issue. And fortunately, you can do that, so no big deal. But your ugly remarks make you look much, much worse even than I do, and by extension Mosher, so I guess Steve wins the Internet?
Willis,
Also, re this:
“You haven’t a clue what Mosh knows, or I know, or anyone else knows.”
How, exactly, do you know what I know about what Mosher knows? Isn’t that incredibly presumptuous to think you know that? And it’s probably even worse for you to make that presumption about me, since you literally know nothing about me, whereas we both know a fair amount about Mosher.
I know that Mosher comments on this block quite frequently, because I have been a regular reader of this blog for years, and I read the comments sections an awful lot. Did you know that about me? Probably not. I also know that Mosher has his own climate blog, because there’s a link to it on this blog above. I’ve checked it out, and clearly Mosher has a lot of technical stuff to say about climate, which means he’s studied the issue in depth. I’ve read Mosher arguing here on all kinds of complex climate issues. So I know that he knows about climate, the general issues of the debate, the arguments made on both sides, etc. So I think it’s a fair assumption to make that he knows about the very things that I brought up, and that you elaborated on.
As for knowing what you know, I have read this blog almost every day for several years now, and probably have read almost everything you’ve written here. So I know you know quite a bit about climate science yourself. Without your replying, I would have guessed that you knew exactly what I was talking about here, and been right. I would also have guessed that you would have had prior experience with Mosher, and had a decent idea of his level of knowledge about climate science, since he’s a regular and his blog is referenced above by Anthony.
So do I have anything wrong here? Have I made a single false presumption about anyone? Obviously your statement above is complete nonsense, and you should admit that it was nonsense, because obviously you and Mohser have left a whole lot of clues around as to what you think and know about climate issues. You should apologize not only because you didn’t have the knowledge to make those claims about me, but even worse, because they were quite wrong.
The only think I don’t know, is how much drinking or smoking of herb you’ve been doing lately, that might account for this pointless attack on me. But since I don’t know you that well, I won’t make that presumption. Maybe it was just unseasonably hot in your neck of the woods. In any case, I hope you are at least enjoying this little tiff. I know I find it most amusing.
Best regards, and hoping you have a sense of humor to go with your outrage.
***
phlogiston says:
January 24, 2013 at 7:19 pm
It is also unclear why the Younger Dryas is talked about as if it is something exceptional. It is not. It is simply one of several dozen similar spikes which characterise climate instability during glacial periods – albeit one of the largest spikes.
****
True, but what distinguishes the YD is the mass extinction of N Amer & other continental large animals, when they had breezed thru all the previous excursions.
brokenyogi says:
January 25, 2013 at 3:04 pm
Since I haven’t yet learned to read minds, what another man knows and doesn’t know is an eternal mystery. He may know something and not reveal it. He may not know something and act like he knows it. He may even know it and not know that he knows it. He may have known it once and then forgotten it. Or, and perhaps most commonly, what you and he are talking about is subtly different, so what he knows is not apparent.
And you want to convince me that you can see into Mosh’s mind and tell us what he knows and doesn’t know … good luck with that.
You ask:
Yes, there’s a missing context. You’ve accused Steven of acting improperly, of putting on a false front, of pretending not to know something he knows. That is an accusation that he is acting in bad faith. You said:
and
You have absolutely no evidence that he is pretending. You absolutely do not know what Steven knows or why he said what he said. Die gedanken sind frei.
In fact, I suspect he didn’t understand what you were referring to. Which is why I tried to clarify things by pointing out what it was I thought you were talking about (which was not totally evident from your words). You made an uncited, unreferenced claim that “the AGW types” made some vague claim. I was guessing myself, as I said at the time:
When you blow in, call someone a tool, and then accuse them of pretending to be ignorant of something, which means that they are acting in bad faith … yeah, you did something wrong here.
Me, I’m willing to walk away from this.
w.