Two-fifths of that ice loss occurred in the last five years, a three-fold increase in the pace at which Antarctica is shedding its kilometres-thick casing, a consortium of 84 scientists reported in the journal Nature.
The findings should dispel any lingering doubts that the continent's ice mass is shrinking, the authors said.
They also highlight the existential threat facing low-lying coastal cities and communities home to hundreds of millions of people.
"We now have an unequivocal picture of what's happening in Antarctica," said co-lead author Eric Rignot, a scientist at NASA's Jet propulsion Laboratory who has been tracking Earth's ice sheets for two decades.
"We view these results as another ringing alarm for action to slow the warming of our planet."
Up to now, scientists have struggled in determining whether Antarctica has accumulated more mass through snowfall than it loses in meltwater run-off and ice flows into the ocean.
But more than two decades of satellite data -- the new findings draw from 24 separate space-based surveys -- have finally yielded a more complete picture.
Covering twice the area of the continental United States, Antarctica is blanketed by enough ice pack to lift global oceans by nearly 60 metres (210 feet).
More than 90 percent of that frozen water sits atop East Antarctica, which has remained mostly stable even as climate change has driven up Earth's average surface temperature by a full degree Celsius (1.8 degrees Fahrenheit).