More than a hundred thousand years ago, the increase in temperature of just two degrees led to a catastrophic melting of the Antarctic glaciers. The released water increased the sea level by almost four meters. It could happen again, warn researchers. These findings are outlined in a scientific paper published in the journal PNAS.
the company 129-116 thousand years ago known as the last interglacial. It shares the penultimate and the last (which ended about 11 thousand years ago) glaciation in Earth’s history.
the sea Levels in that era he was 6-9 meters higher than today. And if liquid water in the last interglacial period was much higher, the ice was significantly less than it is now. This, according to geologists, making it a model effects of the current global warming.
scientists estimate that the melting of Greenland could raise sea levels by no more than two meters. More meter could add to the melting of mountain glaciers and thermal expansion of ocean waters (with increasing temperature the water begins to occupy a larger volume). The conclusion suggests itself that the rest of the uplift provided melted the glaciers of Antarctica. Other major water reserves on Earth just yet.
However, direct evidence is almost not there. Behind them and went to the ice continent, the team led by Chris Turney (Chris Turney) the University of New South Wales in Australia.
the researchers studied samples of ice to reconstruct the history of the ice cover.Photo from AntarcticScience.com.
the Most vulnerable part of the Antarctic ice sheet — the West. Here most of the ice just lying on the bottom of the sea, washed by the waters of the ocean.
“the Western Antarctic ice sheet is submerged in water and now the water is getting warmer and warmer,” says Terni.
As you know, where thin, there and tear. And climate scientists wanted to know was torn whether here in the last milenkova and how loud went “Bang”.
Scientists did not have a multimeter to drill wells to extract ice cores. Instead, they went to the area where similar work was done by nature itself.
Explain that some areas of Antarctica are extremely strong winds erode the upper layers of the ice, exposing areas millennia ago. Because of the peculiar color of this ancient ice and is blue.
“Instead of having to drill miles of ice, we can take a walk on the blue ice area and back to Millennium,” explains Turney.
I take samples, the scientists subjected them to a multilateral analysis. In the course went the isotopic composition of the ice, the composition of the air bubbles, the study of volcanic ash left by the well-known and accurately dated volcanic eruption, and even the DNA of ancient bacteria.
All these sources of information pointed to the same thing: in the last interglacial period the ice is melted.
the researchers performed computer simulations to understand how quickly this happened, how much water eventually got into the ocean and how in Antarctica warmed up before the crash.
the Ancient ice told about the large-scale melting of more than a hundred years ago.Photo from AntarcticScience.com.
the Calculations showed that the temperature rise less than two degrees Celsius was enough to a large part of the ice sheet of West Antarctica melted in the past several centuries. This has increased the sea level at 3.8 meters (!). The majority of this growth occurred in the first two hundred years.
“we Now have the first serious evidence that Western Antarctica melted, and this was the cause of much of the sea-level rise”, says Terni.
These results can be called frightening. According to the report of the intergovernmental panel experts on climate change in 2013, the global sea level will rise in the next hundred years at 40-80 cm, and the contribution of the Antarctic ice will be limited to five centimeters. A new study shows that this figure is repeatedly underestimated.
“Paris climate agreement requires us to limit global warming this century to two degrees Celsius, ideally one and a half degrees, says Terni. Our results show that we should not approach the warming of two degrees”.
in Other words, humanity is already on the edge, to be followed by a precipitous melting of ice of Antarctica and sea-level rise of several meters, and this can happen in this century.
However, while the researchers took samples only one point in the Antarctic. They plan to collect samples from several more regions to double-check your data.
By the way, earlier “Conduct.Science” (nauka.vesti.ru) wrote about how global warming reacts the Arctic and why it can lead to cold in Western Europe.