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."
How did this get in here. Fire the Editor!
""The next ice-age is not imminent," said Dr Wolff, "and greenhouse warming makes it even less likely"
Right. Some "Blam" threads tie into evolution, if they're about continental drift or something. Otherwise, even if I find a thread interesting to me personally, I don't ping the evo list. The science subset of the evo list is usually for cosmology, relativity, or maybe other physics topics. At least that's the kind of thread upon which the list was built. There are "mars" threads and "space" threads maintained by others, and I don't want to duplicate those. I try to keep my ping lists narrowly focused, so I don't become a promiscuous pinger.
Thanks. I usually abandon a thread when the crevos show up.
When people like Promiscuous Henry crash the party, there goes the neighborhood!
Big surprise there!
LOL!
I have a list for this and its not one of those mentioned above.
That is the problem with the rights, farm, environemt list I use. Because property rights are so tied into the environmental movement and agriculture I included all three for my list but the number of posts and pings was getting to be too much as you have seen in my freepmail. I have had to cut back and be a little more discriminating.
You know your ping list is too broad when people start dropping out in large numbers. I seriously try not to be obnoxious about pings. Originally, I thought I "knew" who should be on my list, but I made mistakes, and I learned not to make those decisions for people. For the last 2 or 3 years, I only add people who specifically request to be included. And even then, I check out their postings to be sure they're right for the list. I guess I take this stuff too seriously.
No, I think you take it just right. My lists, with the exception of the short list which is my personal list, were all created by request only. I don't get people dropping in large numbers but do get the occasional reqest to be pulled. Everyone was warned it was high volume. The list seems to rest consistantly at about 200 names. The GGG list is also about that size. It's not one of the larger lists on this forum but propably contains some of the most dedicated as all are activists in these areas.
My list grows very slowly, and it's not all that large, just 135 names at the moment. The subset of my list that I use mostly for cosmology and physics threads is maybe half that size. So the numbers are small, but the quality is awesome! Of course, the evolution threads aren't for everyone because they sometimes become quarrelsome, and my list is limited to the evolution side of the issue. I assume the creationists have their own ping list, but I don't know who runs it. I've seen no evidence of such a ping list being used in the evolution threads. My guess is that the creationists notify one another mostly by freepmail.
Thanks!
Actually, that data is grouped in periods of about 1700 to 2300 years. I'm glad you see my point ;-) We would need to take our average C02 for the last 2000 years to make a comparison that is statistically valid, not the last ten years.
Ping.
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