Reserves of ice in Antarctica over the past 25 years has declined significantly

Over the past 25 years Antarctica has lost more than 3 trillion tons of ice. The loss of ice over the last 5 years has increased dramatically. Such findings stated in one of the most extensive research on the state of the ice cover of the continent. The work was conducted by an international group of 84 scholars, analyzed the data, collected through satellite observations from 1992 to 2017.

The Researchers found that the icy continent at the moment, losing their supplies of ice three times faster than he did prior to 2012. The level of annual losses estimated at more than 241 billion tons. The aggregate loss reserves of the Antarctic ice sheet over the past 25 years has raised Global sea level about 8 millimeters. Moreover, in the last 5 years account for about 40 percent of this growth (about 3 mm).

Raise Global sea level by a few millimeters at first glance does not seem impressive, but even until then, if you do not remember the results of previous studies, which argued that global climate change would have no impact on the decline in the ice cover of Antarctica. New data indicate that the ice cap of the continent is not that resilient to climate change (primarily warming), and we should therefore revise the forecasts of its potential impact on Global sea level. A preliminary analysis conducted by an international team of scientists suggests that the melting of the total ice of Antarctica, Global sea level may rise by 58 meters.

The scientists ' Report was published June 13 in the journal Nature Research and became one of the five reports on the status of Antarctica, published at the same time. Taken together, these studies encompass both the past and present state of the continent to determine the level of impact of these changes on global climate change. In addition, it discusses issues affecting the role of human activities on the continent, and discusses options for protecting the environment and Geology.

Ice broke

"For their study, the researchers selected three types of data obtained through satellite observations of changes in the situation on the continent," — says co-author Andrew shepherd of Leeds University (UK).

With the help of satellites, equipped with altimeters, scientists obtained data on the thickness of the ice contained in Antarctica. With the help of other satellites data were obtained on the speed of the ice releases to the ocean. The third type of data allowed to calculate the level of gravity of the created land, and figure out the total weight of the ice caps of Antarctica.

Each of these methods individually has limitations. For example, certain factors, such as the variability of the amount of snow lying on the ice cap, or change in the composition of species residing beneath the ice, may affect satellite measurements. However, the combination of all three methods, explains shepherd, the researchers were able to separate the factors that prevented the determination of the state of the ice of Antarctica.

"the Satellite measurements showed us that the ice layer is much more dynamic than we all used to take", — he says.

"If you look at the first report of the intergovernmental panel on climate change (IPCC), presented 30 years ago, before we launched the satellite study of the polar regions, you will see that scientists had not even considered the possibility of ice caps in any way to respond to global climate change. For a long time in glaciology (the science of natural ice) was taken for granted the notion that the ice sheet is not can change quickly. But, as shows our research, it was a mistake," — said shepherd.

the Results of a study published by NASA in 2015, warned about the high probability of a split of the Antarctic ice shelf Larsen B hundreds of icebergs before the end of this decade

In total from Antarctica during the study a period of 25 years disappeared 3 trillion tons of ice. Only in the last year from the ice shelf Larsen C broke iceberg weighing over 1 trillion tons – one of the largest in history – and covering half of the island of Jamaica.

The Greatest change in the level of annual losses of the Antarctic ice sheet, observed in the Western part of the continent, occurred in 2012. Thus, the volume of ice loss, which amounted annually 58 billion tonnes, over the past 5 years rapidly increased to 175 billion tons, the researchers report. At the same time, the annual volume of ice loss of the Antarctic Peninsula, amounting to 7 billion tons in the period from 1992 to 2012, reaching 36 billion tonnes from 2012 to 2017. Mainly due to the destruction of glaciers.

C accelerated pace

Antarctica is perennially covered by ice, but its ice caps for many thousands of years in the framework of the annual cycles and then decreasing, then increasing. Clues from the geological record suggests that climate changes are reducing the volume of ice in Antarctica and thus do it much quicker than it happened under natural circumstances in the past.

Ancient ice sheets left on earth where they lie, signs of their presence in the past. Based on these characteristics, scientists can determine where it had previously been already melted glaciers. This is done in the framework of observations of the seafloor around the Western part of the continent. Here are the underwater remains of glaciers, pointing to exactly where they were in the past, explains shepherd.

All these features allow scientists to estimate the rate of retreat of Antarctic ice. In the past between glacial cycles, the annual rate was about 50 meters. However, recent observations indicate that the rate of decrease of ice has increased more than 20-fold and now annually amounts to about 1 kilometer.