Greenland ice sheet close to point of no return, reveals computer model

Scientists have now modeled the tipping points to determine when that melt might occur in terms of carbon emissions.

The team identified two Greenland Ice Sheet tipping points using computer model simulations.

According to the study, releasing 1000 gigatonnes of carbon will cause the southern portion of the ice sheet to melt. On the other hand, as much as 2500 gigatonnes of carbon emission will cause nearly the entire ice sheet to disappear. 

Approximately 500 gigatonnes of carbon have already been added, putting humanity nearly halfway to the first tipping point.

“The first tipping point is not far from today’s climate conditions, so we’re in danger of crossing it. Once we start sliding, we will fall off this cliff and cannot climb back up,” said Dennis Höning, a climate scientist at the Potsdam Institute for Climate Impact Research, in an official statement.

Greenland ice loss happening at a faster rate

Greenland is one of the most vulnerable places on the planet to global warming. According to data, it lost up to 255 gigatonnes (billions of tons) of ice per year between 2003 and 2016.

Scientists have observed that the southernmost part of the ice sheet is melting the fastest. The statement reveals that air and water temperature, ocean currents, precipitation, and other underlying factors all influence how and where the ice sheet melts. 

In terms of temperatures, previous observations suggested that a global temperature increase of one to three degrees Celsius could cause the Greenland Ice Sheet to melt irreversibly.

“We cannot continue carbon emissions at the same rate for much longer without risking crossing the tipping points. 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, who led the study. 

The results have been published in AGU’s journal Geophysical Research Letters.

Study abstract:

Understanding the future fate of the Greenland Ice Sheet (GIS) in the context of anthropogenic CO2 emissions is crucial to predict sea level rise. With the fully coupled Earth system model of intermediate complexity CLIMBER-X, we study the stability of the GIS and its transient response to CO2 emissions over the next 10 Kyr. Bifurcation points exist at global temperature anomalies of 0.6 and 1.6 K relative to pre-industrial. For system states in the vicinity of the equilibrium ice volumes corresponding to these temperature anomalies, mass loss rate and sensitivity of mass loss to cumulative CO2emission peak. These critical ice volumes are crossed for cumulative emissions of 1,000 and 2,500 GtC, which would cause long-term sea level rise by 1.8 and 6.9 m respectively. In summary, we find tipping of the GIS within the range of the temperature limits of the Paris agreement.