Analysis of Arctic Sediments Show that Late 20th Century Warming is Unlike Natural Variation; “Unprecedented” Change
25 October 2009
An analysis of sediment cores from an Arctic lake indicates that biological and chemical changes occurring there are unprecedented over the past 200,000 years and likely are the result of human-caused climate change, according to a new study led by the University of Colorado at Boulder. A paper on the work was published online 19 October in the Proceedings of the National Academy of Sciences.
While environmental changes at the lake over the past millennia have been shown to be tightly linked with natural causes of climate change—such as periodic, well-understood wobbles in Earth’s orbit—changes seen in the sediment cores since about 1950 indicate expected climate cooling is being overridden by human activity such as greenhouse gas emissions. The research team reconstructed past climate and environmental changes at the lake on Baffin Island using indicators that included algae, fossil insects and geochemistry preserved in sediment cores that extend back 200,000 years.
The past few decades have been unique in the past 200,000 years in terms of the changes we see in the biology and chemistry recorded in the cores. We see clear evidence for warming in one of the most remote places on Earth at a time when the Arctic should be cooling because of natural processes.
—lead author Yarrow Axford of CU-Boulder’s Institute of Arctic and Alpine Research
The study included researchers from CU-Boulder, the State University of New York’s University at Buffalo, the University of Alberta, the University of Massachusetts and Queen’s University in Kingston, Ontario.
The sediment cores were extracted from the bottom of a roughly 100-acre, 30-foot-deep lake near the village of Clyde River on the east coast of Baffin Island, which is several hundred miles west of Greenland. The lake sediment cores go back in time 80,000 years beyond the oldest reliable ice cores from Greenland and capture the environmental conditions of two previous ice ages and three interglacial periods.
The sediment cores showed that several types of mosquito-like midges that flourish in very cold climates have been abundant at the lake for the past several thousand years. But the cold-adapted midge species abruptly began declining in about 1950, matching their lowest abundances of the last 200,000 years. Two of the midge species adapted to the coldest temperatures have completely disappeared from the lake region, said Axford.
In addition, a species of diatom, a lake algae that was relatively rare at the site before the 20th century, has undergone unprecedented increases in recent decades, possibly in response to declining ice cover on the Baffin Island lake.
Our results show that the human footprint is overpowering long-standing natural processes even in remote Arctic regions. This historical record shows that we are dramatically affecting the ecosystems on which we depend.
—co-author John Smol of Queen’s University
The ancient lake sediment cores are the oldest ever recovered from glaciated parts of Canada or Greenland. Massive ice sheets during ice ages generally scour the underlying bedrock and remove previous sediments.
Since much of the Arctic was covered by big ice sheets during the Ice Age, with the most recent glaciations ending around 10,000 years ago, the lake sediment cores people get there only cover the past 10,000 years. What is unique about these sediment cores is that even though glaciers covered this lake, for various reasons they did not erode it. The result is that we have a really long sequence or archive of sediment that has survived arctic glaciations, and the data it contains is exceptional.
—co-author Jason Briner, University of Buffalo
The study was funded by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada and the Geological Society of America.
A study published in Science magazine last month that reconstructed past temperatures in the Arctic using ice cores, tree rings and lake sediments concluded that recent warming around the Arctic is overriding a cooling trend caused by Earth’s periodic wobble. (Earlier post.) Earth is now about 0.6 million miles further from the sun during the Northern Hemisphere summer solstice than it was in 1 BC—a trend that has caused overall cooling in the Arctic until recently.
Resources
Yarrow Axford, Jason P. Briner, Colin A. Cooke, Donna R. Francis, Neal Michelutti, Gifford H. Miller, John P. Smol, Elizabeth K. Thomas, Cheryl R. Wilson, and Alexander P. Wolfe (2009) Recent changes in a remote Arctic lake are unique within the past 200,000 years. PNAS doi: 10.1073/pnas.0907094106
Darrell S. Kaufman, et al. (2009) Cooling Recent Warming Reverses Long-Term Arctic Cooling. Science 325, 1236 doi: 10.1126/science.1173983
One more piece of evidence.
Isn't it surprising to see this quick Arctic warming spell while the sun is further away from Earth?
Unbelievers will claim that Earth wobble is the main reason and that (as usual) man-made GHG has nothing to do with it.
We had a well known doctor on TV the other day who claimed that H1N1 should be ignored beause it will not kill more than 1 to 3 million people. He also believed that GHG will not affect us. Next day, more than 60% of his patients apparently cancelled their appointment. The other 40% seem to agree with him. Does this mean that about 40% are unbelievers or nosayers or that he his a good doctor?
Posted by: HarveyD | 25 October 2009 at 07:46 AM
Scientists believe the earth is 4.5 billion years old, but the cores go back only 80,000 years...is this really enough to draw any serious conclusions? It's like saying there is going to be a permanent bull stock market market into the future with only a day or two of data (relatively speaking).
Posted by: ejj | 25 October 2009 at 07:49 AM
.
Who funded this "study," and what kinds of obscene profits, cushy jobs, and fat retirement plans are coming from repeating the same old Globalwarmist dogma?
It's all about the $$$$$$$$. "Research" money, government control (hmmmmm.... research performed at government schools) of people's lives, and the almighty dollar!
Our savior, Algore, has become quite wealthy off of the Globalwarmist religion. PRAISE be unto Algore!
.
Posted by: The Goracle | 25 October 2009 at 03:01 PM
Actually ejj the "cores go back in time 80,000 years beyond the oldest reliable ice cores from Greenland." And yes that is enough to draw conclusions. And even if it wasn't it's like Harvey said, it's just "one more piece of evidence:" One more out of thousands.
Posted by: ai_vin | 25 October 2009 at 03:10 PM
Academia is littered with "studies" that involved small sample sizes and "might be" "could be" types of conclusions drawn by researchers. Global warming is another case, 80,000 years or 800,000 years, the evidence is still a tiny fraction of what scientists believe to be the history of earth - 4.5 billion years...between 80,000 (or 800,000) years, they have NO DATA. There are also no other planets throughout the universe that had human populations & industries that pumped CO2 into the air and caused the warming of their planets. There has been no experimentation conducted on other planets similar to earth with the scientific method to validate the global warming hypothesis.
Posted by: ejj | 25 October 2009 at 04:06 PM
...between 80,000 (or 800,000) years and 4.5 billion years, they have no data...without data it's speculation & even courts don't allow it (normal ones anyway)....
Posted by: ejj | 25 October 2009 at 04:09 PM
Goracle,
Did 'Al' knock you back?
Posted by: arnold | 25 October 2009 at 05:02 PM
"Scientists believe the earth is 4.5 billion years old", ejj you are probably a creationist, so you shouldn't really comment on evidence-based studies, as your other peers that seems to spend time scavenging the web for GW news to comment...
Anyway, in the first few billions of years the atmosphere was completely different from what is now, it was not supporting complex life forms and it would be pretty pointless to compare with the current situation.
The core dates 200.000 years back, not 80.000. In the last 200.000 years there has been a couple of ice ages, so is not that this period was not covering the possible variations of earth's climate. Other studies use cores from 600.000 years back.
Posted by: Alessio | 26 October 2009 at 01:32 AM
How to lie with statistics ...
- sediment cores register for many thousand of years the abundance of 'mosquito like midgets' (?? midget like mosquitos??).
- the resolution of the data is rather high, variations within 50 year periods are clearly visible.
Assume the shortest time interval to measure the abundance of 'midgets' (mosquitos?) is about 10 years, otherwise how to conclude there is a steep decline the last 50 to 60 years (??).
This means the researchers must have made 20000 samples and counted the midgets per sample. How accurate are each of these samples: is each sample really spanning about 10 years, or do older samples span many more years than accounted for by the researchers? Are they really counting 'midgets'; maybe the older samples contain many 'non-midgets' mistaken by the researchers for 'midgets' ?? even several midget species are mentioned: I really wonder if such observations can be made from very old ice-core samples.
Etc, etc, and many many more critical remarks can be made. The end-conclusion can be just another "mistake" (I am not speculating about political agendas and who is paying these researchers for what ever reason).
If you ask me, the research results are too wonderful to be true, so do the conclusions have any credibility?
Posted by: Koen | 26 October 2009 at 06:57 AM
What's coming down the pike is that shortly every homeowner will be required to retrofit his or her house to lower its carbon foot print. This to be paid for by bonds issued by every town in the US. The bonds are to be paid off by individual homeowners using his or her house as collateral.
Just another tax burden on the beleagerd tax payer who still hasn't paid off the bank bailout or bought an electric golf cart to get to work.
Who is pushing for this wonderful rip off? The green building industry in cooperation with the eco freaks of course.
Posted by: Mannstein | 26 October 2009 at 07:52 AM
Koen: All good questions. I'm glad you're thinking critically. Those are just the sorts of questions that cannot slide in a peer reviewed publication. As a result, answers to your questions are given in the "Materials and Methods" section of the paper.
Goracle: The answers to your questions are given in the "Acknowledgments" section of the paper.
Posted by: Nat Pearre | 26 October 2009 at 08:53 AM
Again, between 80,000 (or 800,000) years and 4.5 billion years, scientists have NO DATA. There are also no other planets throughout the universe that had human populations & industries that pumped CO2 into the air and caused the warming of their planets. There has been no experimentation conducted on other planets similar to earth with the scientific method to validate the global warming hypothesis. There are more valid reasons to support renewable energy (like eliminating the influence of thug regimes) than the shaky "science" of climate change.
Posted by: ejj | 26 October 2009 at 07:45 PM
Koen,
( How to lie with statistics ...)?
You may have a subscription that gives you access to something - I dont.
The link to this article summary from the above Colarado University website:** according ** reads
"An analysis of sediment cores from an Arctic lake indicates that biological and chemical changes occurring there are unprecedented over the past 200,000 years and likely are the result of human-caused climate change, **according*** to a new study led by the University of Colorado at Boulder. A paper on the work was published online 19 October in the Proceedings of the National Academy of Sciences."
"The sediment cores showed that several types of mosquito-like midges that flourish in very cold climates have been abundant at the lake for the past several thousand years. But the cold-adapted midge species abruptly began declining in about 1950, matching their lowest abundances of the last 200,000 years. Two of the midge species adapted to the coldest temperatures have completely disappeared from the lake region, said Axford"
No mention of midgets there.
The salient point though is probably the reson for your reaction.
"While environmental changes at the lake over the past millennia have been shown to be tightly linked with natural causes of climate change -- like periodic, well-understood wobbles in Earth's orbit -- changes seen in the sediment cores since about 1950 indicate expected climate cooling is being overridden by human activity like greenhouse gas emissions."
Care to comment?
Posted by: arnold | 27 October 2009 at 01:27 AM
"There are more valid reasons to support renewable energy (like eliminating the influence of thug regimes) than the shaky "science" of climate change."
-
Thank you, ejj.
Now, just go along with GW. Why fight it? What's the point. It's good for this country whether it's true or not.
Posted by: danm | 27 October 2009 at 01:09 PM
"There are more valid reasons to support renewable energy (like eliminating the influence of thug regimes) than the shaky "science" of climate change."
-
Thank you, ejj.
Now, just go along with GW. Why fight it? What's the point. It's good for this country whether it's true or not.
Posted by: danm | 27 October 2009 at 01:09 PM
I happen to believe climate change is a reality, and that some of the current change is indeed caused by us.
However, if someone on the other side of the fence presents opposing evidence, sure, I'll consider it. And I will consider the *scientific* evidence without trying to connect it to a political agenda, corruption, the end of freedom, blah-blah-blah.
One person objecting here in several posts hasn't even addressed the fact that the scientists who wrote the report explicitly state that yes, there are natural causes of climate change, and that right now, due to orbital wobble -- a well-understood event -- we're further from the Sun than is sometimes the case. That means the Arctic should be *cooling,* yet the evidence suggests it's not only not cooling but is almost certainly warming.
And much is made in some posts of the fact that the core sample reflects "only" the past 200,000 years or so, a small slice of the estimated age of the Earth, 4.5 billion years. That 200,000 years is a finger-snap, in relative terms, is utterly beside the point. That slice of time represented in the sample is the *most* relevant slice of equal size to right now.
There's another factor not addressed in the quotes from the report here (though it may be in the full version, which I've not read) that bears on this discussion. That is, yes, ice ages have come and gone repeatedly, with the interglacial periods warmer. In fact, I read just a few days ago that during one remote interglacial period, the average global tempterature is estimated to have been some 9 degrees F higher than the global average today. However, those changes take place over millenia, not decades. And thousands of pieces of evidence from countless scientists the world over indicagte that despite the fact we *should* be cooling (orbital wobble again), we're *not.*
I sometimes read that this is nothing but a plot led by the U.S. A few months ago I read that argument, so I spent a couple days crafting a reply, providing links to sources all over the world from governments, public universities and research instutes, private universities and research institutes, and various NGO's. I *also* provided links to the scant few contrarian sites I could find -- most of which, by the way, I discovered had hidden connections, such as to oil companies. That reminded me of the "scientists" on the payrolls of tobacco companies who assured us tobacco is harmless.
I did not mention a single word about politics or anything like that, though I did say right off I'm American, so I darned sure want to know if my country is leading me down the primrose path.
What kind of response from the person to whom I replied? I can't quote it verbatim, but it was along the lines of this: "You must be one of those Obama lovers trying to make us communists so we can have one world government!" What that response did *not* include was a single syllable of comment on the links I had provided, nor even presenting other contrarian links.
My politics are irrelevant, but I wrote back that yes, I voted for three Democrats: the President, VP, and a candidate for my local constable's position. I also voted for one Independent for a statewide office. The rest of my votes? -- Republicans. So I can hardly be classified as a pro-communist, treehugging, one-world-government kind of guy.
I will, as I said, listen to anyone who comes with a voice of reason and *evidence* -- not diatribes, but evidence. I have an acquaintance who is a retired geophysicist who happened to spend his career in the oil industry. While he doesn't *deny* climate change, he's definitely a skeptic, and I'll listen to him all day long (and have).
Finally, I've lived in Bangkok over 15 years. I don't need Al Gore or anyone else telling me something's going on. All I have to do is to go to the seashore and marvel at how much it has moved inland in such a short time. True, that's merely one anecdote, so indicative of nothing on a global scale by itself -- but it mirrors experiences in thousands of places all over the planet. And those observable-with-your-own-eyes do indeed provide a powerful argument that *something* is indeed going on -- and it's not good.
Posted by: Account Deleted | 30 October 2009 at 04:23 PM