Skip to comments.Ice Cores Unlock Climate Secrets
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.
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.
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."
Looks like we have about 18,000 years more of good weather, huh?
I'd like to see what it shows for those interesting periods of bad, bad weather in that book by Baille.
But...but... but, I thought it was all SUVs' and Bush's fault.
18:00 09 June 04
NewScientist.com news service
As long as humans do not mess it up, the Earth's climate is set at fair for the next 15,000 years. That is according to information extracted from the oldest ice core ever drilled.
The Antarctic core is the first to reach as far back as a warm period with characteristics similar to our own interglacial. So it should help make more accurate predictions about when to expect the next deep freeze.
The ice core, drilled from a feature in central Antarctica called Dome C, is around 3 kilometres long and 10 centimetres wide. Changes in the relative proportions of hydrogen isotopes in the ice layers allow scientists to compile a complete record of Antarctic temperatures going back 740,000 years.
The core shows the waxing and waning of eight ice ages. Most critically for making predictions about our climate, it is the first core to record a period known as Termination V, around 430,000 years ago.
At this point, the world moved from a glacial period into a long, warm interglacial, similar to this era. The previous longest ice-core record, drilled by the Soviet Union at Vostok in Antarctica between 1980 and 1988, went back only 420,000 years.
"All interglacials are slightly different, but we believe Termination V is the most similar to our own," says chief author of the new study, Eric Wolff, at the British Antarctic Survey in Cambridge, UK. It mirrors the pattern of solar warming between seasons and at different latitudes that are caused by fluctuations in the Earth's orbit known as the Milankovitch cycles.
It shows that the Termination V interglacial was unusually long, lasting 28,000 years. The current interglacial is now 12,000 years old, and some scientists feared that we might be heading for an ice age soon since at least one post-Termination V interglacial lasted just 10,000 years.
But the new findings suggest that even without the human hand in global warming, a new ice age would be unlikely for perhaps another 15,000 years, Wolff says.
The core also sheds light on how ice ages have changed over the past million years. Since Termination V, ice ages have been very intense, with periods of cold weather that blanketed much of the northern hemisphere in ice for 80,000 years punctuated by short interglacials lasting typically 20,000 years.
But the new core shows that, prior to Termination V, the cold and warm periods of the glacial cycle each lasted around 50,000 years but were much less intense.
"Marine deposits suggested some of this, but it stands out much more clearly in the ice record," Wolff says.
Meanwhile, European and US scientists are discussing plans to survey for a site in Antarctica that will extend the record still further. "We want to go back at least 1.2 million years next time," Wolff says. "But we have to find somewhere that we can do it."
Journal reference: Nature (vol 429, p 623)
Yup, but like they say....it's not the heat-it's the humidity.
Some of the Ice Cores support his ideas...some don't.
The problem with the next Ice Age won't be the cold. It will be that the potable water will be locked up in the ice. We will have to mine the ice for water and pipe it to the farms and cities. In a way it will be like what they used to imagine on Mars.
Can we expect an apology from the envirowackos of Kyoto? Maybe just a little "Oops" from Algore?
I would think that a record of southern hemisphere volcanic activity might be enclosed in that ice, too.
As to the duration of the current warm spell, they'll have to explain a little more about what they think causes warm spells and why this one looks similar to the one 400,000 years ago. If they just wave their arms at the data they aren't doing much more than the TV weatherman.
I would think that a record of southern hemisphere volcanic activity might be enclosed in that ice, too.
was it Krakatoa that went off in indonesia about 75,000 years ago--and is reputed to coincide with a period in which the human gene pool was generally slimmed down?
the article mentions another ice core that went back 420,000 years so Krakatoa should have showed up there. likely there are others--because krakatoa time frame is not that great.
in any case the info on krakatoa should already be in ice cores previously drilled.
It was. Bush, Cheney and Halliburton all went back in a time machine and over a period of 150 million years, they committed genocide against the dinosaurs (impacting minorities and women, mostly), finally killing them all off about 60-65 million years ago so they would have oil in the ground to start wars over.
Krakatoa was fairly recent. Was heard in London or something.
Buy SUV's and stop the next ice age!
No, that was the Toba volcano.
Did we steal the oil from the dinosaurs in the first war for oil?
As compared with the air outside that was manufactured, what, last year?
I doubt that the air in the bubbles is exactly the same composition as the air of the time it was entrapped. But relative differences between air bubbles of different age might be noted.
The composition is different. The core is like a pile of bottles, that were closed one each year for the last 0.75M years. The one on the bottom has the oldest air in it.
Already I don't like this.
Which reminds me: it's floodin' down in Texas. Is this an el nino or a la nina year, anybody know?
Pretty rainy here in WV. I may have heard it would be a "mild El Nino." Unless that was last year.
|The last glacial period was preceded by 1000 years of the coldest temperatures of the Late Pleistocene, apparently caused by the eruption of the Mount Toba volcano. The six year long volcanic winter and 1000-year-long instant Ice Age that followed Mount Toba's eruption may have decimated Modern Man's entire population. Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago. The survivors from this global catastrophy would have found refuge in isolated tropical pockets, mainly in Equatorial Africa. Populations living in Europe and northern China would have been completely eliminated by the reduction of the summer temperatures by as much as 12 degrees centigrade.
Volcanic winter and instant Ice Age may help resolve the central but unstated paradox of the recent African origin of Humankind: if we are all so recently "Out of Africa", why do we not all look more African?
Because the volcanic winter and instant Ice Age would have reduced populations levels low enough for founder effects, genetic drift and local adaptations to produce rapid changes in the surviving populations, causing the peoples of the world look so different today. In other words, Toba may have caused Modern Races to differentiate abruptly only 70,000 years ago, rather than gradually over 0ne million years.
|The Mount Toba eruption is dated to approximately 71,000 years ago. Volcanic ash from Mount Toba can be traced north-west across India, where a widespread terrestrial marker bed exists of primary and reworked airfall ash, in beds that are commonly 1 to 3, and occasionally 6 meters [18 feet] thick.
Tambora, the largest known historic eruption, displaced 20 cubic kilometres of ash. Mount Toba produced 800 cubic kilometres.* It was therefore forty times larger than the largest eruption of the last two centuries and apparently the second largest known explosive eruption over the last 450 million years.
*Mount St Helens produced a tiny 0.2 cubic kilometres.
|Mount Toba's eruption is marked by a 6 year period during which the largest amount of volcanic sulphur was deposited in the past 110,000 years. This dramatic event was followed by 1000 years of the lowest ice core oxygen isotope ratios of the last glacial period. In other words, for 1000 years immediately following the eruption, the earth witnessed temperatures colder than during the Last Glacial Maximum at 18-21,000 years ago.
For the volcanic aerosols to be effectively distributed around the earth, the plume from the volcanic eruptions must reach the stratosphere, a height greater than 17 kilometres. Mount Toba's plume probably reached twice this height. Most solar energy falls at low latitudes between the Tropics of Cancer and Capricorn, so eruptions that happen near the Equator cause much more substantial cooling due to the reflection of solar energy. Toba lies 2 degrees north of the Equator, on the Island Sumatra.
The reduction in atmospheric visibility due to volcanic ash and dust particles is relatively short-lived, about three to six months. Longer-term global climatic cooling is caused by the highly reflective sulphuric acid haze, which stays suspended in the upper atmosphere for several years.
Ice core evidence implicates Mount Toba as the cause of coldest millennium of the late Pleistocene. It shows that this eruption injected more sulphur that remained in the atmosphere fo a longer time [six years] than any other volcanic eruption in the last 110,000 years. This may have caused nearly complete deforestation of southeast Asia, and at the same time to have lowered sea surface temperatures by 3 to 3.5 degrees centigrade for several years.
|The Volcanic Winter/Weak Garden of Eden model proposed in this paper. Population subdivision due to dispersal within African and other continents during the early Late Pleistocene is followed by bottlenecks caused by volcanic winter, resulting from the eruption of Toba, 71 ka. The bottleneck may have lasted either 1000 years, during the hyper-cold stadial period between Dansgaard-Oeschlger events 19 and 20, or 10ka, during oxygen isotope stage 4. Population bottlenecks and releases are both sychronous. More individuals survived in Africa because tropical refugia were largest there, resulting in greater genetic diversity in Africa.|
Small and portable, this red ochre stone is engraved with what must be "tally" marks. It is one of two such stones recently found in the Blombos Cave in South Africa and have been dated as being 77,000 years old, making them the oldest form of recorded counting ever found.
Krakatau erupted in the 1880s. There was a pretty neat show on Discovery Channel about that recently.
yeah got it. i was thinking of toba 71,000 years ago, a super volcano. looks like its recorded in soil as well as ice samples.
Oh, it's even worse than that. It's an El Reno year, which means the summer will be dominated by a large mass of hot air that can cause severe burns among the residents of Waco, Texas.
Will your posts be waving in gassy brown and green?
Super Volcano Toba(75,000 Years Ago)
"Their is substantial evidence to show that within the time of the super volcano Toba's eruption in the Indonesian Pacific, the world's population of homo sapiens decreased from over one hundred thousand to less than two thousand, basically because global temperatures dropped five degrees for many years. This was within the current interglacial and at its start. "
I've read that this event can still be seen in the human genetic record.
So, the human species is the product of an interglacial..... when the cold resumes, so will the species.
Interestingly, recently I read about an ancient human site in Indonesia just above the Toba ash layer.
Do you stand gaping in awe at a T-Rex skeleton purported to be 100 million years old, or do you gag in astonishment at the fools who believe such nonsense?
I've heard it described as the loudest sound ever heard by humans...and, it 'echoed' around the world seven times.
I wonder how closely they can narrow down a time period when they are looking back across that many years. Really, the C02 levels that they talking about today as so high represent a few years - 10, 20 or so. Averaged across the last century they likely are still really normal. Can they find a section that correlates to a particular century? I wouldn't think so - I think they'd be lucky to be able to identify particular 1000 year time spans. That means that statistically it's meaningless to compare this years C02 to anything they find in the cores.
That would be like taking the last few letters of a book and comparing them to the entire book - "THE END has a far greater representation the the capital E than the rest of the book, demonstrating a trend toward increasing capitalized vowels". Comparing this year to nearly a million years worth of ice core is just as meaningless.
It's been so long since her, I'm gonna have to find her html and amend it. You know any CGEB posts from then?
Really, I did laugh out loud.
It hurts to laugh, anymore.
Frequent identifiable volcano ash layers in the ice core help some with the dating.
That depends on if Al Gore sees his shadow.
Nope. But looking forward to the waving gassy brown posts. You could do...um...seaweed?
This could take awhile to analyze; each foot represents 40.4 years.
Good info, thanks.
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.
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