Research shows that Greenland’s ice is beginning to melt faster than at any time in the last 12,000 years, which will raise sea levels and could have a significant impact on ocean currents.
New measurements show that the melting rate coincides with any of the geological records for the Holocene period – defined as the period of the last ice age – and is likely to accelerate, according to an article published in the journal Nature.
Increased ice loss is likely to lead to an increase in sea level between 2 cm and 1
Jason Briner, a professor of geology at the University of Buffalo and lead author of the article, said: “We have changed our planet so much that the rate of melting of the ice sheet in this century is at a rate to be greater than anything we have seen beneath the natural variability of the ice sheet over the last 12,000 years. “
These changes in a relatively short period of less than a century seem unprecedented. The Greenland ice sheet shrank between 10,000 and 7,000 years ago and has been slowly accumulating over the last 4,000 years. The current melting will reverse this pattern, and within the next 1,000 years, if global warming continues, the vast ice sheet is likely to disappear completely.
If greenhouse gas emissions continue to rise sharply, the melting rate could accelerate further to four times that found over the last 12,000 years.
“We are increasingly confident that we will experience unprecedented levels of ice loss from Greenland unless greenhouse gas emissions are significantly reduced,” wrote Andy Ashwanden of the Geophysical Institute at the University of Alaska Fairbanks in a commentary accompanying the study.
The findings underscore the extent of the changes that human actions are making on the planet. Last week, a separate team of scientists found that the melting of Antarctica’s ice cap would continue even if the world met the Paris Agreement’s goal of keeping temperatures rising to no more than 2 ° C and eventually raising sea levels by 2.5 meters at this level of heating.
Although the Antarctic ice cap, like Greenland’s ice sheet, will take centuries to melt, research has found that the melting trend triggered by human climate change is likely to be extremely difficult, if not difficult. impossible to be reversed.
Arctic sea ice is also melting at a rapid pace. This year’s summer sea ice minimum was the second lowest in 40 years of continuous measurements. Unlike the ice sheet of Greenland, which is located on land, the ice cap of the Arctic floats and so its melting will not have much effect on sea levels.
However, its melting accelerates warming further by reducing the earth’s albedo – the reflection of light back into space by ice – and exposing the darker water below, which absorbs more heat.
The findings also follow a study from last month that last year’s melting in Greenland was probably the worst in centuries.
The team behind the latest Greenland study made its estimates by creating a computer model of part of the southwestern region of the ice sheet over the past 12,000 years and then forecasting it for the rest of this century.
They checked their findings against what can be said to have actually happened to the ice, through satellite measurements and other instruments, as well as by mapping the position of beryllium-10-containing stones.
They are deposited by glaciers as they move, and measurements of beryllium-10 can reveal how long the rocks were located and therefore where the edge of the ice sheet was when the stone was deposited.
“Prior to our study, science was not doing well with long-term trends in the rate of ice loss in Greenland,” Briner said.
“Very thorough work has been done to quantify today’s rate of ice loss in Greenland, but we did not have a long-term view to put today’s levels in perspective. Our study provides this perspective. “