Ice losses are rapidly spreading into the inside of the Antarctic, a new analysis of satellite data shows.
The South Ocean warming leads to glaciers slipping into the sea faster, with frost now being lost five times faster than in the 1990s. The West Antarctic ice sheet was stable in 1992 but up to a quarter of its width is now thinning. More than 100 meters thick ice has to be lost in the worst places.
The loss of the West Antarctic ice sheet would completely drive up sea levels about five meters, drowning coastal cities around the world. The current losses double every decade, the scientists said, and sea level rise is now running at the end of the projections made a few years ago.
The research, published in Geophysical Research Letters, compared the 800m ice sheet height measurements between 1992 and 2017 with weather information. This differentiated short-term changes due to snow variation of long-term climate changes.
“Starting in the 1990s, thinning has gradually spread over the last 25 years – that's fast in glacial terms,” said Professor Andy Shepherd, from the University of Leeds in the UK, led the study. “He used to mention the speed of ice-pulling in an ice sheet in geological schedules, but the age of people has now replaced that.” T
He said that thinning some ice streams extended 300 miles into the land along their 600 mile length. “Thinning has affected more than 50% of Pine Island and Thwaites glacier basins over the last 25 years. We have reached halfway and that is our concern. ”
Researchers already knew that ice was being lost from West Antarctica, but the new work indicates where it happens and how fast. This will enable more accurate projections of sea level rise to be made and can help prepare for these increases.
In the recent past, the ice of the Antarctica glaciers fell into the balance of ice lost as icebergs melted into the sea. But now the glaciers are flowing faster than snow can replenish them.
“Along 3,000km [1,850-mile] a piece of West Antarctica, the water in front of the glaciers is too hot, ”he said. This causes the bottom side of the glaciers to melt where they are crushed against the sea bed. The melting reduces the friction and allows the glaciers to slide our faster to the ocean and thus become thinner.
“In parts of Antarctica, the ice sheet has thinned by extraordinary amounts,” says Shepherd.
Separate research published in January found that ice loss from the entire Antarctic continent had increased by six times since the 1980s, with the largest losses in the west. The new study shows that West Antarctica has caused 5mm sea level rise since 1992, consistent with the findings of the January study.
The expansion of the seas as they warm up and the massive melting in Greenland are the main causes of the rising oceans, but Antarctica is the largest ice store. The East Antarctic ice sheet contains enough ice to raise sea level by about 60 meters. It was considered stable, but research in December found that even this stronghold showed signs of melting.
Without rapid cuts in carbon emissions driving global warming, the melting and sea level rise will continue for thousands of years.
“Before we had useful satellite measurements from space, most glaciologists thought that the polar ice sheets were isolated from climate change and had not changed at all at all, ”Shepherd said. “Now we know it's not true.” T