»Ice Cores: Ice Ages«
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news.bbc.co.uk... Ice cores unlock climate secrets By Julianna Kettlewell 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 large team 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 (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. "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 different types, or isotopes, of hydrogen atoms. Different colds Deuterium is a heavy isotope 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." 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. Predicting the future 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 the 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." 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 humankind'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." posted by NeoProgram |
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| in-my-opinion.orgTechnology, Computers, Science, InternetScience (Assorted topics)Ice Cores: Ice Ages |
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 being a biology man this latest scientific endevour is fascinating but there are many of the enviromentalists who are going to leap on the findings to hammer people again most people don't realise that only 400 years ago there were grape vinyards in scandanavian countries it was so warm films such as "the day after tomorrow" only further heighten the misplaced hysteria around envirimentalist issues consider this enviromentalist like the concpet of "preservation" of endangered habitatis and species isnt is possible that humans are only carrying out the role given to them by evolution of their intelligence and so species that die off as a result of that are merely victims of natural selection? the whole point of evolution even without human intervention has shown that many ecosystems were never meant to bew preserved this is why we have pioneer and climax communities in nature...a rock face becomes covered in lichen and moss...this moss when "dies" leaves a nutrient soil for larger plants and this continues until eventually very large plant and trees colonise the same peice of land...so the conservationist would try to intervene at a certain point to preserve it at a certain state and this itself if against the laws of natural selection posted by the anomaly |
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 ...we are consuming more than we produce, we are destroying trees and follage at an alarming rate and nature 'cant' replace it fast enough. If it was upto business then we wouldnt have any forrests left and without trees we don't breath. Unless the govornment is sitting ontop of a secret alien machine that produces air? In the immortal worlds of Arnie in Total Recall..."Get your ass to Mars!"  posted by Crossfade |
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the problem of dwindling rainforest is another hyped up problem theyre are vast areas of ocean that are essentially dead(no or very little life) massive floating fences off areas filled with blue green algae would easily compensate for the loss of the rainforsets the problem with losing the rainforests is the wildlife and the possible herbal and medicinal plant they contain...that's the only real worry posted by the anomaly |
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 Quote: the problem with losing the rainforests is the wildlife and the possible herbal and medicinal plant they contain...that's the only real worry Aliens have some bases hidden in the Brazilian rain forest. Only the military knows where. 
posted by knn |
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..surely we cant rely on the algae with all the fresh water being dumped into the sea? sooner or later the ballance will swing and no, i don't get my info from 'The day after tomorrow' posted by Crossfade |
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 Quote: sooner or later the ballance will swing The problem I think is just the opposite, why the salinity of the ocean doesn't go up (see below, or  *Living organisms maintain a salinity which is roughly equal to that of the oceans. Previously it was thought that this was because natural selection tended to assist those organisms which were in balance with their surroundings. The question remained, why has the ocean managed to maintain a constant level of salinity? The ocean's present salinity is around 3.4%. If it were to go much above 4%, then basic cell functions such as the maintenance of membrane potential would fail. There would be mass extinctions of life in the oceans. And yet there is no evidence of such extinctions in the last 500 million years. This is quite strange, because salt is constantly being deposited in the oceans through the weathering of rocks, yet its concentration is only 10% of saturation levels. Furthermore, there has been a multitude of cataclysmic events such as meteorite impacts, periods of glaciation and so on which one might expect to abruptly alter salinity. Indeed, attempts to model the salinity regulation using chemistry or physics have failed. So what is regulating the oceans? From Daisyworld ♣ we might predict that the answer is the organisms that live in the oceans. In fact, bacteria play a particularly important role in the running of the oceans (as in most life processes). Although they constitute only 10-40% of the ocean biomass, their high surface area to volume ratio means that they make up 70-90% of the biologically active surface area. And they all pump salt* posted by mymla |
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The time now is 22 May 2012, 05:48 php B.B. |