Study links Greenland ice sheet collapse, sea level rise 400,000 years ago
CORVALLIS, Ore. – A new study suggests that a warming period more than 400,000 years ago pushed the Greenland ice sheet past its stability threshold, resulting in a nearly complete deglaciation of southern Greenland and raising global sea levels some 4-6 meters.
The study is one of the first to zero in on how the vast Greenland ice sheet responded to warmer temperatures during that period, which were caused by changes in the Earth’s orbit around the sun.
Results of the study, which was funded by the National Science Foundation, are being published this week in the journal Nature.
“The climate 400,000 years ago was not that much different than what we see today, or at least what is predicted for the end of the century,” said Anders Carlson, an associate professor at Oregon State University and co-author on the study. “The forcing was different, but what is important is that the region crossed the threshold allowing the southern portion of the ice sheet to all but disappear.
“This may give us a better sense of what may happen in the future as temperatures continue rising,” Carlson added.
Few reliable models and little proxy data exist to document the extent of the Greenland ice sheet loss during a period known as the Marine Isotope Stage 11. This was an exceptionally long warm period between ice ages that resulted in a global sea level rise of about 6-13 meters above present. However, scientists have been unsure of how much sea level rise could be attributed to Greenland, and how much may have resulted from the melting of Antarctic ice sheets or other causes.
To find the answer, the researchers examined sediment cores collected off the coast of Greenland from what is called the Eirik Drift. During several years of research, they sampled the chemistry of the glacial stream sediment on the island and discovered that different parts of Greenland have unique chemical features. During the presence of ice sheets, the sediments are scraped off and carried into the water where they are deposited in the Eirik Drift.
“Each terrain has a distinct fingerprint,” Carlson noted. “They also have different tectonic histories and so changes between the terrains allow us to predict how old the sediments are, as well as where they came from. The sediments are only deposited when there is significant ice to erode the terrain. The absence of terrestrial deposits in the sediment suggests the absence of ice.
“Not only can we estimate how much ice there was,” he added, “but the isotopic signature can tell us where ice was present, or from where it was missing.”
This first “ice sheet tracer” utilizes strontium, lead and neodymium isotopes to track the terrestrial chemistry.
The researchers’ analysis of the scope of the ice loss suggests that deglaciation in southern Greenland 400,000 years ago would have accounted for at least four meters – and possibly up to six meters – of global sea level rise. Other studies have shown, however, that sea levels during that period were at least six meters above present, and may have been as much as 13 meters higher.
Carlson said the ice sheet loss likely went beyond the southern edges of Greenland, though not all the way to the center, which has not been ice-free for at least one million years.
In their Nature article, the researchers contrasted the events of Marine Isotope Stage 11 with another warming period that occurred about 125,000 years ago and resulted in a sea level rise of 5-10 meters. Their analysis of the sediment record suggests that not as much of the Greenland ice sheet was lost – in fact, only enough to contribute to a sea level rise of less than 2.5 meters.
“However, other studies have shown that Antarctica may have been unstable at the time and melting there may have made up the difference,” Carlson pointed out.
The researchers say the discovery of an ice sheet tracer that can be documented through sediment core analysis is a major step to understanding the history of ice sheets in Greenland – and their impact on global climate and sea level changes. They acknowledge the need for more widespread coring data and temperature reconstructions.
“This is the first step toward more complete knowledge of the ice history,” Carlson said, “but it is an important one.”
Lead author on the Nature study is Alberto Reyes, who worked as a postdoctoral researcher for Carlson when both were at the University of Wisconsin-Madison. Carlson is now on the faculty in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
“Reblogged this on This Got My Attention and commented:
Whoa, Nelly! The Greenland icesheet collapsed WITHOUT man-caused global warming 400,000 years ago. How will the alarmists work this into their models?”
1. It was warm.
2. The cause (forcing was not C02)
“The climate 400,000 years ago was not that much different than what we see today, or at least what is predicted for the end of the century,” said Anders Carlson, an associate professor at Oregon State University and co-author on the study. “The forcing was different, but what is important is that the region crossed the threshold allowing the southern portion of the ice sheet to all but disappear.
You see a firm today set by an arsonist. You look back in time and you find a fire 100 years ago set in the exact same place. It was set by lightening. The fact that both arsonists and lightening
can cause fires means you have to take care in doing attribution. Finding a fire in the past set by lightening tells you NOTHING about the fire set today by an arsonist.
How will it be worked into the models? Well, one thing that is hard to model is loss of ice.
But now they have a way of testing various approaches.
What is the physical evidence to support the contention that the previous warming was caused by variations in the Earth’s orbit? Isn’t it possible it was due to variations in solar activity?
That was well into the Pleistocene. And we worry about our little blip on the back of a wimpy interglacial that teeters on the edge of the next onset of ice.
“The sediments are only deposited when there is significant ice to erode the terrain. The absence of terrestrial deposits in the sediment suggests the absence of ice.”
And yet there is plenty of smooth granite bedrock without sediment in the wilderness. Teachers used to pin that on the last glacial period.
Wondering also, now when the Glacier Girl has been removed, what other sediments than terrestrial deposits did they discover in Greenland.
My wife has a Master’s degree in Education and was a Middle School Principal for 20+ years, and I can out-spell and out-write her and 99% of her [gov’t educated] teachers. And science? Fugedaboutit. So I get endless pleasure out of reading what a graduate with an English degree wrote:
You see a firm today set by an arsonist… It was set by lightening. …lightening, lightening, lightening. So it wasn’t a typo.
Anyway, that off my chest, Mr. Abbott opines that the risk of an asteroid strike is very small compared to the risk of just allowing CO2 concentration to keep increasing.
I challenge Mr Abbott to list evidence of any global harm due to the rise in that trace airborne fertilizer. If there is no verifiable, measurable ‘harm’ due to more CO2, then CO2 is ‘harmless’, no?
Abbott asks, do you think the rise in concentration since the Industrial Revolution is natural ?
Of course it is natural. A little of it is produced by human activity, which is entirely natural. CO2 is also beneficial to the biosphere. There would be more people starving today if we did not emit CO2. Literally. Maybe Mr Abbott could expound on why he would prefer starvation.
Ah. . . Clem ”
perhaps I am the only other one who knows where that name comes from…..
I’d like to recommend “Wall of Science”
I beleive that is near Dutch Elm Street
Steven Mosher says:
June 26, 2014 at 8:40 am
Among the many objections to your hand-waving special pleading is the fact that 800,000 years ago the southern dome had also melted away. And that it partially melted during the Eemian interglacial.
The simplest & best explanation is that during the past 2.6 million years earth cools & warms in natural cycles. The Holocene has been cooler than both MIS 11 & the Eemian, so natural “catastrophic global warming” is perhaps less likely now than 400 Ka & 100 Ka, but orbital mechanics suggest that the 400 Ka & 800 Ka interglacials resemble the Holocene, so the jury is still out.
The one potential “forcing” that can categorically be excluded is man-made CO2.
Jaakko Kateenkorva says:
June 26, 2014 at 1:37 pm
Glacier Girl was taken out of ice nowhere near bedrock.
Well Greenland fell apart 400kyrs ago. What a tragedy.
Oh wait on; not to worry. It all grew back again, and it’s ok now.
Wow for awhile there I was a bit concerned.
Frankly, I think the study of climate, particularly in the past, to be a gigantic waste of time and money. Can’t do anything about it anyway.
Just try getting ten people from ten different countries to agree completely on when and where to have a meeting.
Now try that for seven plus billion people; all to agree to do something.
Don’t mind looking at next week’s weather. But climate 30 years ago, or 30 years from now is of no value whatsoever.
Taphonomic says:
June 25, 2014 at 2:25 pm
Gosh darn that Neanderthal man and his Flintstonemobiles!
——————————————————————————–
Fred drove a zero emission car made of stone, don’t blame him. It was Barney Rubble in his wooden Barneymobile that led to the meltdown. By taking a tree out of the carbon cycle to produce his vehicle, Barney removed a co2 absorber from the system and when he eventually had to scrap the car, after the incident involving Bam Bam and the Algoresaurus, the junk yard burned the chassis and carbon dioxide was released back into the atmosphere.
So it was Barney, not Fred, who should bear the blame. Fred was innocent!
This kind of study is actually much shakier than it might seem from the press release. Studies of maritime deposits can only tell about glaciers that reach the coast. Once the icecap has retreated inland it becomes effectively invisible in the maritime record.
So they can potentially tell which parts of Greenland had ice-free coasts, but not the conditions inland (where icecaps can actually become thicker when they can no longer calve into the sea). To complicate things further currents in the Eirik Drift area change greatly between glacials and interglacials.
Incidentally for Greenland ice to raise sea-level by six meters requires almost complete deglaciation, something we know from periglacial deposits in northern Greenland has not happened for about 1.8 million years.
However these big figures are needed to explain the vastly overblown sea-level rise figures in vogue for MIS 11. These are due to the exceptional length of MIS 11 which allowed isostatic adjustment to proceed much further than during other interglacials, a fact that is almost always ignored by “climate scientists” who do not understand geology. These high figures are invariably from tectonically unstable areas, or areas in the “forebulges” of the Eurasian or Laurentid icecaps (like Bermuda or the Bahamas). Actually evidence from tectonically stable areas far from any icecap, like South Australia, strongly suggests that sea-levels in MIS 5 and MIS 11 were approximately the same and about 2-5 meters higher than at present.
“The climate of 400,000 years ago was not that much different than that of today”
Anders Carlson, co-author
<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>
The climate was much warmer then than todays: tropical and sub-tropical fauna and flora in England. Carlson’s goof is the sort of drivel that you get from the alarmists. He wants to panic people into thinking that catastropic melting of the Greenland ice cap is just around the corner.The climate scam continues unabated.
Oh yes, do not believe any reports about rising sea levels. They are steady, but fabricating a rising sea level has become a minor industry with the alarmists. Sea level trend is flat and has been some 15-20years: see the NOAA mean sea level trends for the west coast and Gulf coast tidal guages.
Steven Mosher says:
June 26, 2014 at 8:40 am
You see a fire today set by an arsonist. You look back in time and you find a fire 100 years ago set in the exact same place. It was set by lightening. The fact that both arsonists and lightening
can cause fires means you have to take care in doing attribution. Finding a fire in the past set by lightening tells you NOTHING about the fire set today by an arsonist.
Going down the logic road is ill-advised since logic has to be suspended for CAGW to work. Aristotle, Bacon, Popper etc are not the friends of CAGW.
Look, during the Holocene there have been about 20 episodes of multidecadal warming very similar to the one from 1970-2000. These are known to be caused by the completely normal and expected oscillation of a dissipative chaotic-nonlinear climate system emerging as multidecadal-centennial shifts in ocean currents. All this in the Holocene during most of which temperature has been slowly declining and at the same time CO2 slowly rising:
http://rogerfromnewzealand.files.wordpress.com/2010/01/holocene_delta_t_and_delta_co2_full2.jpg
So now in the 20th century we get upswing number 20. Remind me again how we get to “this one has to be the exception due to CO2”??
CAGW attempts at logic to deny climate history takes forms such as:
“An arsonist starts a fire. Over in Florida lightning set fire to a tree. So CO2 causes global warming.”
or
“A man is found with a knife in his back. But my gran used a kitchen knife to slice carrots. Ergo – CO2 causes global warming”.
This is not logic but rage and denial against logic which is – correctly – perceived as a threat.
If you have got to copy & paste, then even that is worth it as this kind of science shows, at least as far as I can see, that there is absolutely no correlation between T and CO2 that suggests that CO2 is the main driver for T (Temperature)
Ice Core Data from Vostok, Siberia
http://www.geocraft.com/WVFossils/temp_vs_CO2.htmlBased on the analysis of entrapped air from ice cores extracted from … ( approximately 0.6° C, globally) that appears to have occurred over the past century. … slightly and surface temperatures have ceased warming — even as CO2 concentrations have continued to increase (3). … Carbon Dioxide -vs- Temperature Graphs: …
Sorry, my fault. – Try the one below in stead;
http://www.geocraft.com/WVFossils/temp_vs_CO2.html
And then there is this one from the other end of the Earth;
http://mclean.ch/climate/Ice_cores.htm
Well, I may not agree with the stance of this page & many of the other commenters, but I will give ya’ll this much.. The manner in which you (the blogger) write about it, as well as the content & attitude of the comments here, are a breath of fresh air, as far as its done with civility/thoughtfulness/decorum/& a certain understanding & respect for science/scientists. So bravo for that! 🙂
(I read an anti-climate change article on the Tea Party ‘News’ Network, & the manipulative misleading juvenile simple-minded & irresponsible writing in the article, & the long stream of horrifying ignorant mean-spirited & irrational comments, were all jst terribly depressing. I seriously felt a bit freightened b,,,,,,,,,–zy the idea that those people have any influence in America’s policy making.)
Other than that, my only other comment is re: sea level rise…. So, whether it be man-made or natural, if the sea level rises, shouldn’t we prepare for this..?? I mean, there are A LOT of people who either dont know or dont believe this is happening (mostly due to the more irrational skeptic voices telling them it will all be fine & things arent/wont change). And, unlike the last time this occurred, we now have a multitude of major metropolises inhabited by ever increasing populations, which are seaports or coastal cities.. And it may not sound like much (4-8ft), but thats enough to do significant damage, & even submerge cities/islands/etc.
There are a bunch of problems involved if this happens – relocating people/jobs/industry, financial burdens, etc.. And theyre only gonna get worse the longer we wait to take action. But the continued debate is holding up the process & hindering us frm working on solutions to cope with this. Its frustrating, to say the least. :/
Well, actually, the natural rise of sea levels by the year 2100 that you so greatly fear is not going to be stopped by anything you require doing.
And the penalty for immediately trying to limit CO2 releases – which will do nothing to stop, slow, reduce, or limit the sea level rise of 4 feet (actually only about 2 feet by 2100 years is probable) is the immediate murder of millions each year for the next 86 years, the immediate harm of billions each year for the next 86 years by restricting their energy use and increasing their energy costs and reducing their energy reliability. Your “Precautionary Principle” requires we immediately hurt billions of innocents today and for years to come not only to gain “nothing” now or in the future; but only to require actions which could at best only trivial reduce the probability of a result (increasing temperatures and increasing CO2 levels) that will not only do no harm, but are beneficial in and of themselves!
So, who does gain by a world government by harming billions for 86 years and killing millions each year? Who does gain power, money, influence, control, domination, and prestige? Who controls the states’ grants, funds, research, and promotions? Who are the anonymous people who are controlling your emotions to give them power? Who gains from their increase of their power?
What “solutions” are YOU proposing to increase the world’s energy supplies and resources to improve lives? Everything I see is the demand that “we” do something that harms innocents and empowers the government and its enabling propagandists and priests.
Oh, by the way, what part of “anti-climate change” do you think any rational person believes in? Those who believe as their stated government-academic-bureaucratic religion that restricting man’s CO2 levels now will change the world’s future climate are the ones who deny climate change.