Posted on 06/09/2004 3:27:33 PM PDT by blam
Ice cores unlock climate secrets
By Julianna Kettlewell
BBC News Online science staff
Tiny bubbles of ancient air are locked in the ice
Global climate patterns stretching back 740,000 years have been confirmed by a three kilometre long ice core drilled from the Antarctic, Nature reports. Analysis of the ice proves our planet has had eight Ice Ages during that period, punctuated by rather brief warm spells - one of which we enjoy today.
If past patterns are followed in the future, we can expect our "mild snap" to last another 15,000 years.
The data may also help predict how greenhouse gases will affect climate.
Initial tests on gas trapped in the ice core show that current carbon dioxide (CO2) levels are higher than they have been in 440,000 years.
Nobody quite knows how this will alter our climate, but researchers hope a detailed picture of past fluctuations will give them a better idea.
Distant worlds
A cohort of scientists, from 10 different countries, has spent most of the last decade extracting the mammoth column of ice from a location called Dome C, on east Antarctica's plateau.
The European Project for Ice Coring in Antarctica, or Epica, aims to unlock the climatic secrets of our past - and in doing so gain a better understanding of what we can expect in the future.
This is not the first ice core project - but it ventures much further back in time.
Dome C contains 800,000 years worth of snowfall, allowing Epica to obtain a climate record two times longer than its nearest ice core rival.
The Antarctic camp was home to over 50 scientists
"We think this project will really change the way we look at climate," said co-author Eric W. Wolff, of the British Antarctic Survey, Cambridge, UK.
Telling tales
Each slice of the ice core tells tales about the distant world it came from.
For instance, scientists can work out climate by looking at the ratio of hydrogen isotopes.
Deuterium is a heavy isotope - or version - of hydrogen. If a sample of ice has a lot of it, that means the temperature was warmer - and vice versa.
"At very cold temperatures a great deal of the heavy isotopes have rained out," explained Jerry F. McManus, of Woods Hole Oceanographic Institution, US. "So all that is left is what we would call isotopically depleted or lighter. That is how we know how cold it was."
He added: "You might say Antarctica is always cold - and you'd be right. But there is great variation in the degree of cold."
Another important thing that scientists can 'read' in the ice, is the relative concentration of atmospheric gases.
That is because minute bubbles pock mark the core, within which tiny pockets of preserved air lie.
"That is the wonderful thing about ice cores," said Professor McManus. "There is air from three-quarters of a million years ago and it is still locked in these bubbles - it's incredible."
We think this project will really change the way we look at climate
Eric W. Wolff, the British Antarctic Survey, UK Epica is still busy analysing the ice core's atmospheric gases, but preliminary results suggest that present CO2 levels are remarkably high.
"We have never seen greenhouse gases anything like what we have seen today," said Dr Wolff.
Lengthy heat wave
Over the last 800,000 years the Earth has, on the whole, been a pretty chilly place. Interglacials - or warm spells - have come every 100,000 years and have generally been short-lived.
Over the last 400,000 years, interglacials have lasted about 10,000 years, with climates similar to this one. Before that they were less warm, but lasted slightly longer.
We have already been in an interglacial for about 10,000 years, so we should - according to that pattern - be heading for an Ice Age.
But we are not.
The Epica team has noticed the interglacial period of 400,000 years ago closely matches our own - because the shape of the Earth's orbit was the same then as it is now.
That warm spell lasted a whopping 28,000 years - so ours probably will too.
"The next ice-age is not imminent," said Dr Wolff, "and greenhouse warming makes it even less likely - despite what the Day After Tomorrow says."
Every chunk of ice-core tells tales about the distant world it came from
Predicting the future
Epica scientists hope that after they have fully analysed the ice core's atmospheric gases, they will gain a deeper knowledge of how climate relates to them.
"We will double the timescale over which we can study greenhouse gases," said co-author Thomas F Stocker, of the University of Bern, Switzerland. "We will be able to show what the natural variability is in relation to gases like CO2."
By understanding what greenhouse gases did to global temperature in the past, scientists might be able to predict the effect of man-kind's enthusiastic CO2 belching.
"There is great controversy as to whether human beings have changed the climate, " said Professor McManus. "But there is no doubt about the fact that human beings have changed the Earth's atmosphere. The increased levels of greenhouse gases are geologically incredible."
He added: "It is something of grave concern to someone like me, who sees the strong connection between greenhouse gases and climate in the past."
That depends on if Al Gore sees his shadow.
Nope. But looking forward to the waving gassy brown posts. You could do...um...seaweed?
bttt
This could take awhile to analyze; each foot represents 40.4 years.
Good info, thanks.
"Tiny bubbles of ancient air are locked in the ice" What will analysis of the air show I wonder?
They're hoping it will represent the earth's air over this period of time.
What I mean is: will it contain a different mix of gases? Will it carry microorganisms? Things like that.
Different mixes of gasses for sure. Microorganisms hmmm, don't know.
I recently read that DNA was obtained from a 240 million year old bacteria that was found trapped in a salt crystal.
There are articles in the usual journals.
I understand that completely. My question is how compressed are the layers after the weight of 100,000 years of snow have been on top of them? I would not think that individual years could be distinguished, just broader patterns - more like earth cores than like tree rings. Dig down in the earth and you can see the eons, but only very rarely was there a specific layer that can be certain to have formed in one year (like a volcanic layer). Instead you can see how the earth changed in different periods for sure, but can't determine specific years because of the compression.
I depend on my far-flung network of operatives to alert me when a likely thread makes its appearance. If something somes to my attention too late, I generally let it go. As here.
I think they're still working on the problem from the little I've read. The electrical conductivity was a new one for me. They put electrodes on opposite sides of a core and measure the conductivity. Because the pH is different between summer and winter (which I also didn't know), they can find a yearly boundary. This should only be limited by the fineness of the probes.
I think it's time to start using the word 'cabal'. Much more fun.
When will the cabal be promoted to junta?
I once had to explain to a Communist (SWP-USA) that I was to be referred to as a "lackey" because I had been promoted from "running dog."
The Darwintern continues. (Still haven't been able to obtain that Bilderberger grant.)
Hahaha. I think we need to aquire a compound, or at least a base of operations, before we can escalate to junta. On the other hand, what the hell do I know? I'm feeling very Kerry this morning....let's use both.
Good observation
Here are some data from the Vostok Ice Cores --- Vostok ice data
BP = before present.
" Depth, m - Yr BP - mean age-- Co2, ppmv
3120.61--- 324711 --322827--- 288.4
3123.51 ---325400-- 323485 ---298.7
3129.91--- 327237 --324991--- 285.8 "
Looks to me that the largest CO2 number that I noticed is an average of several hundred years.
The current 370 ppmv CO2 is 24 percent higher than an average of several hundred years --- seems to me that to get an average of 298.7 over several hundred years, some of the data had to be higher, --- and thus, much closer to current data.
The way I categorize this stuff, this is a "blam" thread, not a crevo thread. "Blam" threads are for arguing whether Atlantis had anything to do with Lemuria and were the Celts the Lost Tribes of Israel.
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