In the last 25 years, the world’s largest ice sheet has lost nearly 3 trillion tonnes (3.3 trillion tons) of ice, contributing to an almost 8-millimeter rise in global sea levels. Of that, 40 percent has occurred in the last five years, dumping 200 billion tonnes (220 billion tons) of ice and raising the ocean half a millimeter every year. Scientists now say if the melt rate continues to rapidly increase then it could have serious implications for coastal communities around the world.
Prior to 2012, Antarctica lost 67 billion tonnes (74 billion tons) per year, contributing to a 0.2-millimeter rise in sea levels. Since then, the continent has seen a threefold increase in melt rate, losing as much as 219 billion tonnes (241 billion tons) of ice annually, leading to a 0.6-millimeter sea level rise each year.
The largest change by far is recorded in an area dominated by marine-terminating glaciers known as West Antarctica. Here, ice shelves are being eaten by warm ocean water with some parts appearing as much as 18 percent thinner than 25 years ago. Breakups of ice no longer act as a natural buffer for inland ice and glaciers make their way downstream and to sea much quicker.
Moving next to the finger of land pointing to South America called the Antarctic Peninsula, scientists have recorded a sharp rise in air temperatures that force ice shelves to collapse as the surface ice melts.
Altogether, across the continent, 34,000 square kilometers (13,000 square miles) of the ice shelf has been lost since the 1950s.
The greater part of the continent known as East Antarctica is close to a state of balance, gaining 5 billion tonnes (5.5 billion tons) of ice per year on average. However, scientists say it’s not enough to replace the amount of ice lost. In fact, if all of Antarctica melted, global sea levels would rise by more than 58 meters (190 feet) to cover major coastal metropolitans and create new shorelines.
In the most comprehensive Antarctic assessment to date, 84 scientists from 44 organizations analyzed two dozen satellite surveys to take three different kinds of measurements: changes in ice sheet heights, speed and movement of glaciers, and gravity measurements to understand how gravitational attraction relates to the mass of ice sheets overall. Globally, sea levels are rising 3 millimeters each year and the research published in Nature shows how Antarctica is a key player in what is going on.
