More than 4 trillon tonnes of ice from Greenland and Antarctica has melted in the past 20 years and flowed into the oceans, pushing up sea levels, according to a study that provides the best measure to date of the effect climate change is having on the earth’s biggest ice sheets.
The research involved dozens of scientists and 10 satellite missions and presents a disturbing picture of the impact of recent warming at the poles.
The scientists claim the study, published in the journal Science, ends a long-running debate over whether the vast ice sheet covering the Antarctic continent is losing or gaining mass. East Antarctica is gaining some ice, the satellite data shows, but west Antarctica and the Antarctic peninsula is losing twice as much, meaning overall the sheet is melting.
“The estimates are the most reliable to date, and end 20 years of uncertainty of ice mass changes in Antarctica and Greenland,” said study leader, Andrew Shepherd, of Leeds University. “There have been 30 different estimates of the sea level rise contribution of Greenland and Antarctica, ranging from an annual 2mm rise to a 0.4mm fall.
“We can state definitively that both Greenland and Antarctica are losing mass, and as [the] temperature goes up we are going to lose more ice.”
The study shows the melting of the two giant ice sheets has caused the seas to rise by more than 11mm in 20 years. It also found Greenland is losing ice mass at five times the rate of the early 1990s.