Antarctic ice melting faster than previously thought

Rodiano Bonacci
Giugno 15, 2018

Michele Koppes, a glaciologist at the University of British Columbia, added: "This study shows that we're actually losing more mass along the edges of the ice sheet, where the ice sheet is making contact with the ocean, and that the warming oceans are melting the ice".

From 2012 to 2017, the melt rate increased to more than 241 billion tons a year, according to the study in the journal Nature published yesterday.

Per the team's calculations, a high emissions scenario - in which carbon emissions rise unabated and environmental protections in Antarctica are not implemented - global air temperature would rise almost 3.5°C above 1850 levels by 2070, with sea level rise averaging somewhere between 10-15 mm every year.

The planet's largest ice sheet is now losing more than 240 billion tons of ice every year ― a threefold increase from less than a decade ago.

The study is the product of a large group of Antarctic experts who collectively reviewed 24 recent measurements of Antarctic ice loss, reconciling their differences to produce the most definitive figures yet on changes in Antarctica.

For the new study, the scientists combined data from three types of satellite measurements to track changes in ice over time, study co-author Andrew Shepherd, a professor of Earth observation with the School of Earth and Environment at the University of Leeds in the United Kingdom, told Live Science.

Antarctic ice has retreated and advanced and retreated again many times over the millennia: there has always been argument about how much of the change is because of natural cycles, how much because of human-induced climate change. If all of the glaciers on the southern continent were to melt then sea level would rise by 58 meters (190 feet).

"This has to be a cause for concern for the governments we trust to protect our coastal cities and communities", he said.

The growth is largely attributable to just two huge glaciers - Pine Island and Thwaites. And that ice is melting out at a quickening pace, showing that we're quickly driving the climate over the guard rails that have allowed humanity to flourish. We suggest that Antarctic ice volume variations in response to the range of global temperature experienced over this period - up to 2-3 ̊C above preindustrial, which correspond to future scenarios with Carbon dioxide concentrations between 400 and 500 ppm - are instead driven mostly by retreat of marine ice margins, in agreement with the latest models.

"If we aren't already alert to the dangers posed by climate change, this should be an enormous wake-up call", said Martin Siegert, of the Grantham Institute at Imperial College London, and one of the authors.

In total, sea levels have risen about 8cm since 1992.

Much of the East Antarctic Ice Sheet is land-based. "To do this, we need to keep watching the ice sheet closely, but we also need to look back in time and try to understand how the ice sheet responded to past climate change". And because of the massive amount of ice on the eastern side of Antarctica, we shouldn't take for granted that it's protected from the ice loss being experienced on the other side of the continent. "Things are happening. They are happening faster than we expected".

However, he said that there is growing evidence that projections of Antarctica's influence on sea-level rise may have been underestimated.

The researchers relied on samples taken as part of the global ANtarctic geological DRILLing (ANDRILL) project.

And although you may never get to see Antarctica for yourself, these scientists want you to know that what happens in this remote region has a significant impact in your own backyard.

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