Scientists have found in the mountains in the central part of Antarctica the oldest ice reserves of 2.7 million years old, the study of which indicated that modern ideas about the beginning of the Ice Age can be fundamentally wrong, the news service of the journal Science informs.
“We studied the so-called” blue ice “, which our colleagues usually ignore because it is impossible to single out individual annual layers inside them. It turned out that very ancient layers of ice deposits often remain in such deposits, and ice of this age forces almost everyone A person to pay attention to themselves, “- says Ed Brook (Ed Brook), a geologist from the University of Oregon in Corvallis (USA).
The last glacial period in the history of the Earth, as geologists now believe, began about 2.6 million years ago and it continues to this day. Its main feature is that the area of glaciation and the temperature of the Earth’s surface throughout its entire length were not constant – glaciers attacked and retreated every 40 and 100 thousand years, and these episodes were accompanied by sharp cooling and warming.
These cycles of glaciations and “thaws”, as many scientists today believe, are primarily associated with the so-called cycles of Milankovitch – the “swings” of the Earth’s orbit, changing how much heat poles and temperate latitudes receive. Other geologists and climatologists believe that in fact, these abrupt climate changes are not related to “cosmic”, but completely terrestrial factors, such as rearrangements of the “pipeline” of currents in the world’s oceans, or an increase or decrease in the proportion of CO2 in the atmosphere.
The ice samples found by Brooke and his colleagues in the Transantarctic mountains, in a place called Alan Hills, formed about 2.7 billion years ago, even before the ice age. This is a record ancient ice reserves – in the past, scientists were able to find Antarctic ice formed about a million years ago, which is 1.7 million less than the finding of the Brook team.
Inside this ice, scientists explain, microscopic air bubbles are sharpened, the study of the composition of which will allow us to understand in the near future what kind of climate prevailed on the planet before the beginning of the glaciation and how much CO2 and other greenhouse gases were contained in it at that time.
Their preliminary study has already yielded interesting results – according to geologists, the share of CO2 in air bubbles in these ice reserves was unexpectedly low, much lower than that indicated by the chemical and isotopic composition of shells of mollusks extracted from marine sedimentary rocks of the same time.
If these data are confirmed, this would mean that shells of mollusks and other climatic “chronicles” that palaeoclimatologists use today to study conditions on Earth in the distant past may be fundamentally wrong.
In the near future, scientists plan to test their findings by studying other deposits of the oldest ice that came to the surface of Antarctica as a result of the movement of glaciers along the slopes of the mountains.
As geologists hope, they will be able to find even more ancient ice reserves, formed 5 million years ago or even earlier, when the Earth’s climate was very warm. Their study will show whether fluctuations in the level of CO2 were the main cause of the onset of the ice age or whether it arose as a result of some other climatic or geological processes.
