It's possible that Antarctica alone can add about 16cms to sea level rise by the end of the century, Shepherd said.
But that has changed. From 2012 to 2017, the melt rate increased to more than 219 billion metric tons, according to the study Wednesday in the journal Nature.
The annual sea level rise that's attributed to Antarctica has tripled, from 0.2mm to 0.6mm, or from less than a tenth of an inch to almost a quarter of an inch, he says.
"We're watching these reports closely", said Michiel van den Broeke, professor of Polar Meteorology at Utrecht University in the Netherlands, saying they were the guide for defending the Dutch coast.
The melting is caused by rising ocean temperatures due to climate change.
Antarctica's ice sheet is melting at rapidly increasing rate, now pouring more than 200 billion tons of ice into the ocean annually and raising sea levels a half millimeter every year, a team of 80 scientists reported Wednesday. The latter is increasingly being viewed as posing a potential planetary emergency, because of its enormous size and its role as a gateway that could allow the ocean to someday access the entirety of West Antarctica, turning the marine-based ice sheet into a new sea. That's "an important distinction, because it means it's insulated from changes in the ocean's temperature".
The latest data is a continuation of previous assessments known as the Ice sheet Mass Balance Inter-comparison Exercise (IMBIE), which began in 2011 and tracks ice-sheet loss from 1992 onwards. "There are no other plausible signals to be driving this other than climate change".
Whether Antarctic mass loss keeps worsening depends on choices made today, argues DeConto, who co-authored a separate paper in this week's Nature outlining two different visions for Antarctica's future in the year 2070.
"Some of the estimates covered different proportions of the ice sheets, some of them covered different time periods, and all of them used different methods and so it became hard for people who are not specialists to try to pick them apart", says Shepherd.
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. "We believe that we've captured all of the different satellite records that exist on the planet", he says.
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.
Scientists have previously raised fears about a scenario in which ice loss from Antarctica takes on a rate of explosive growth.
"The increasing mass loss that they're finding is really worrying, particularly looking at the West Antarctic, the area that's changing most rapidly and it's the area that we're most anxious about, because it's below sea level, " said Christine Dow, a glaciologist at the University of Waterloo in Canada who was not involved in the research.
Csatho noted that comparing the first and last five year periods in the record reveals an even steeper acceleration.
Shepherd says that actually, their data shows a "a progressive increase in ice loss throughout the whole 25 year time period".
That might not sound like much, but what's particularly concerning is the way the ice loss has sharply accelerated over the course of the 25-year timeframe. Shepherd says until 2010, the data had been tracking a lower scenario which estimated that Antarctica "wouldn't make much of a contribution to sea level rise at all" because of the effects of higher snowfall. "But remember for the northern hemisphere, for North America, the fact that the location in West Antarctica is where the action is amplifies that rate of sea level rise by up to an about additional 25 percent in a city like Boston or NY".