1 February 2013
Greenland Ice Core May Rewrite Some Climate Books
Posted by Dan Satterfield
The only warm place at NEEM was this dome. Everyone slept in tents heated to 28 degrees. The drilling was done in a trench that was covered by snow.
I spent two weeks in the Summer of 2010 at the top of the World. To be specific I was in the middle of the Greenland Ice sheet at NEEM, about 650 miles from the North Pole, and while there I witnessed the recovery of the oldest core of ice ever recovered from Greenland. NEEM stand for North Greenland Eemian ice core. That ice core has now been analysed, and it had some BIG surprises that will affect the predictions for future sea level rise and climate change in general.
The Eemian was the warm period before the last ice age. It was likely a bit warmer than the interglacial period fo the last 10,000 years or so when human civilization developed.
There has been some good science writing over the past week about the findings, but missing from the writing so far, is the extreme difficulty and hardship that was endured by those involved to obtain this ice core. Drilling a hole one mile deep in ice at the top of the world is not an easy task, but it was information that climate scientists desperately needed. It was accomplished over three years by a superb group of engineers and young scientists. I was honored to spend a couple of weeks with them, and to be there when the drill reached rock beneath the ice.
The Science
The big surprise from the NEEM core is that the Greenland icecap survived the warmth of the last interglacial quite well. It melted back a lot, and the spot where NEEM was located was about 150 meters lower then than now. In general there was still a big icecap in the Eemian, and it was quite a bit warmer than it is now.
Greenland temperatures were around 8 degrees 3C warmer (Excuse the typo!) than the present although this past summer saw an amazing melt in Greenland unlike anything seen in the past hundred years. Sea level was MUCH higher in the Eemian, and many researchers believed this was due to the melting of ice in Greenland and in Antarctica. The NEEM core calls this into question, and it appears that the large rise in sea level may have come more from Antarctica. The West Antarctic Ice Shelf is known to be unstable, but could it be much more sensitive to rising temperatures than was thought? It seems strange when you think about, it but research grants to look at ice in Greenland may end up telling us a lot about Antarctica.
This is me in the NEEM trench with one of the ice cores. That ice fell as snow about 125,000 years ago during the warm period before the last ice age.
The tent in the background was my home at NEEM. 24 hour daylight takes some getting used to!
A paper announcing the findings was published in NATURE this past week, and the editor’s note is a good summary:
A detailed record of Eemian climate
The Greenland ice sheet is losing mass and contributing to ongoing sea level rise, but an incomplete understanding of its changes during the last interglacial 130,000–115,000 years ago, termed the Eemian, have hampered firm predictions. Now an international team has successfully reconstructed the Eemian climate record from the new NEEM ice core. The record shows that in spite of a climate 8 °C warmer than that of the past millennium, the thickness of the ice sheet decreased by only a few hundred metres. In addition, the ice core shows that there was significant surface melt in the north-central parts of the ice sheet during the Eemian, conditions we might soon see again, as demonstrated by melt layers formed at NEEM by the warm temperatures observed over Greenland in July 2012.
An excellent piece in nature describing more fully the impact of this ice core and why it is so important is HERE.
I have written about NEEM before here and here.
Below is a collection of videos I shot at NEEM, and hopefully they give you an idea what it was like to be there. Real science is not setting around in a white coat and staring at a computer screen.
Denmark was the lead research country at NEEM, and the Neils Bohr institute at the Univ. of Copenhagen has a great summary of the findings here. I was the guest of Dorthe Dahl-Jensen and Dr. Jim White of the Univ. of Colorado the lead US Scientist. I plan on writing more on NEEM soon, with some perspective on the findings from Dr. White.
http://www.nbi.ku.dk/english/news/news13/greenland-ice-cores-reveal-warm-climate-of-the-past/
Dan Satterfield has worked as an on air meteorologist for 32 years in Oklahoma, Florida and Alabama. Forecasting weather is Dan's job, but all of Earth Science is his passion. This journal is where Dan writes about things he has too little time for on air. Dan blogs about peer-reviewed Earth science for Junior High level audiences and up.
where do you get a dome like that?
Very well-done. Thanks for taking the time.
DAn, I am curious about this statement that the Eemian was 8C warmer than today. I do not know of any actual data supporting that claim. The diagram in your post is closer to my understanding of the actual temperature difference. There one can see a difference of approximately 3C between the period labeled ‘Eemian’ and the zero point of the graph x axis, which is today. The zero on the y is arbitrarily set to today’s mean global temperature. As one can see from this diagram, the total fluctuation in temperature from glacial to interglacial is more like that 8C value (actually 11C for the diagram). Do you know of any other data not shown?
Hi Rachael,
You are absolutely right, that should have read 3C not 8. It was a typo and I have corrected it. It also depends on what part of Greenland you are talking about so around 3C is more correct. Suffice it to say the Eemian was warmer than preindustrial Greenland and almost certainly 20th century Greenland.
Dan
Dan, thanks for clarifying. I understand that these new data suggest that the local temperature in that area of Greenland was 8C warmer than the local temperature at the same spot today (-25C). Just wanted to make sure others did not infer that the entire earth was that much warmer. Thanks for your posting of this important contribution!