Part of the world's biggest slab of ice is melting 10 times faster than the rest, according to new research.
The study, led by the National Institute of Water and Atmospheric Research, discovered sun-warmed waters beneath the Ross Ice Shelf in Antarctica is to blame.
It's always melting, but how fast the Ross Ice Shelf has been disappearing hasn't been studied until now.
"It highlights a way in which summer warming melts the ice shelf," Dr Mike Williams, NIWA principal scientist, told 1 NEWS.
NIWA researchers and a team from the UK have been studying the Ross Ice Shelf for years, recording it's rate of decline, and why.
They say a piece of shelf is vanishing 10 times faster than the rest.
"This is being driven by warm surface waters moving from in front of the ice shelf to under the ice shelf," Dr Williams said.
Drilling hundreds of metres, the researchers have used radar to measure changes in the ice's thickness and rate of thawing.
Christina Hulbe, an Otago University glaciologist, led another 2018 expedition on the Ross shelf.
"We've been using a hot water drilling system that was built at Victoria University to melt our way through the ice shelf to make a hole that's about 30 centimetres in diameter.
"It goes through about 350 metres of ice to get to the ocean underneath. So it's like we're poking a little pin in the ice shelf to see what's underneath," she said.
It has found we're close to triggering irreversible change in Earth's polar ice sheets.
NIWA's work is raising more fears about rising sea levels.
"We need to understand this process to allow us to separate out the seasonal effects or what might be the natural variability, with what are the man-made increases that we might expect to see in the future," Dr Williams said.
It shows how valuable the researchers' work in Antarctica continues to be.