A few days ago a group of scientists told about the most interesting discovery: in Antarctica it was possible to obtain a sample of ice, the age of which, according to glaciologists, reaches 2 , 7 million years. This is a whole 1.7 million years more than the previous record. The value of this ice is that it is a conserved sample of water and gases, by which one can understand what climatic conditions were on Earth in its past. Frozen gas bubbles in the ice help scientists to determine the composition of the atmosphere that existed on the planet millions of years ago. It was then, about three million years ago, something happened that contributed to the onset of ice and the general cooling of the climate.
The value of this sample is simply incredible, says David Schuster, a geochemist at the University of California, Berkeley. "This is the only sample of the ancient atmosphere of the Earth, which we now have," – said the scientist. This is true, plus obtaining a sample of ice of this age is associated with a number of purely technological difficulties: the well must be very deep, and drilling is necessary in extreme conditions. Plus, the ancient ice is difficult to find, and careful analysis of glaciers in different regions of the Antarctic is required.
Specialists have already analyzed the air from the bubbles frozen into the ice. As it turned out, the carbon dioxide content of 2.7 million years ago was about 300 parts per million, which is much lower than the current figure. According to a number of climatologists, the relatively low content of carbon dioxide in the Earth's atmosphere contributed to the onset of a cold snap. Earlier, the composition of the atmosphere was determined from the fossil remains of animals and plants. But this is a very inaccurate analysis, which, incidentally, showed a higher content of carbon dioxide in the atmosphere than it was determined now.
It is clear that the results obtained need to be rechecked. But if they are fair, then scientists will have to rebuild some parameters of paleoclimatic models. The fact that scientists have discovered so ancient an ice pattern indicates that similar discoveries are possible in the future, perhaps scientists will be able to find even older samples. As a result, specialists will be able to build more accurate paleoclimatic models than those that exist now. In addition, in some cases climatologists and their colleagues find it difficult to say what the composition of the atmosphere was millions of years ago.
Scientists prefer samples of ice in Greenland and Antarctica. Usually it is necessary to drill in regions where truly accumulated ice accumulates for a long time. In this case, climate change can be monitored by layers, as the annual tree rings track the conditions in which this tree grew. Only years here can not be tracked, but thousands of years – without problems. In the case of ice, scientists also conduct an analysis of the gases included in the ice and the ice itself, more precisely, of water. At the moment, the oldest specimen was ice, raised from the bottom of the well in the Antarctic in 2004.
Ancient ice was discovered in East Antarctica, 200 km from McMurdo station. This is the largest settlement, port, transport hub and research center in Antarctica. Belongs to the US Antarctic Program, but also serves stations and research programs of other states. In this region there are deposits of so-called blue (or blue) ice, which is only 1% of the total volume of ice in the Antarctic. It is formed as a result of compression of the fallen snow, which becomes a part of the ice on which it is located. When compressed, bubbles of gas remain in the ice, the ice crystals increase, which gives the ice a blue or even a blue color.
Soon scientists will make a new attempt to break into the past of the Earth with the help of frozen water. This time, they hope to receive an ice sample of 5 million years old, when the concentration of carbon dioxide is believed to be above 300 parts per million. According to some experts, ice in the Antarctic began to form about 30 million years ago (in some regions). Probably, so ancient samples can not be found, since the ice hardly remained unchanged for all these tens of millions of years. But the ice of 3-5 million years old can probably be found.