The assessment of the impact of carbon emissions on the Greenland Ice Sheet reveals that we are midway to reaching a breaking point that may cause a sea level increase of 6 feet. According to the Potsdam Institute for Climate Impact Research researchers, the current amount of CO2 pumped into the atmosphere stands at 500 gigatons. The southern portion of the Greenland Ice Sheet will melt with over 1,000 gigatons of carbon into the atmosphere, raising the sea level by nearly six feet. Once the level reaches around 2,500 gigatons of carbon in total emissions, the entire Greenland Ice Sheet will melt and result in a 6.9-meter (22.6-foot) rise in sea level.
“Once we have emitted more than ~1,000 gigatons of carbon in total, we won’t be able to stop the southern part of the Greenland Ice Sheet from melting entirely in the long term, even if we would entirely stop emitting carbon then. This melting would cause a sea level rise by ~1.8m,” said Dennis Höning, the lead author of the study and climate scientist at the Potsdam Institute for Climate Impact Research. While the entire melting may take hundreds of years to happen, humans then may be powerless to prevent it from happening, added Höning.
With an average annual loss of 255 gigatons of ice between 2003 and 2016, the Greenland Ice Sheet has already begun melting. Factors that influence how rapidly and in regions the ice sheet dissolves include ocean currents, rainfall, air and sea temperature, and other variables. The southern region of the ice sheet has experienced the majority of the melt so far. However, the exact future reaction to various climate and carbon emissions events in the Greenland Ice Sheet stays undetermined because of the intricacy of those components' interactions and the durations for melting ice sheets. As the ice melt goes beyond the threshold, it will continue to melt without brakes. Even with atmospheric carbon dioxide lowered to pre-industrial levels, the ice sheet will not be able to regenerate.
"We cannot continue carbon emissions at the same rate for much longer without risking crossing the tipping points," according to Dennis Höning. "Most of the ice sheet melting won't occur in the next decade, but it won't be too long before we will not be able to work against it anymore," said Höning.