A new study has warned that the melting of the Greenland Ice Sheet will cause global sea levels to increase by more than 10 inches (27cm) even if the entire world stops burning fossil fuels immediately.
National Geological Survey of Denmark and Greenland (GEUS) researchers analyzed two decades’ worth of measurements to estimate the minimum ice loss from the Greenland Ice Sheet due to climate warming to date.
In the best-case scenario, their estimates indicate that the Greenland Ice Sheet will lose approximately 110 trillion tonnes of ice.
According to the study’s lead author, Professor Jason Box, the contribution of the Greenland Ice Sheet to sea level rise will continue to increase under the likely scenario of continued global warming.
The committed mass loss from the Greenland Ice Sheet more than doubled to 78 centimeters (30 inches) if the high melt year of 2012 is used as a hypothetical average constant climate later in this century.
In the study, researchers examined changes in the snow line of the Greenland Ice Sheet from 2000 to 2019. The snow line is the boundary between places exposed to net melting during summer and areas that are not.
The ice does not melt evenly across the sheet, with the ice at lower altitudes at the edges melting the quickest.
Further up the ice sheet, even in summer, it is too cold for melting to occur.
The snow line is the line at which the upper layer of winter snow does not melt throughout the summer, but instead remains on top, sustaining the ice sheet.
This line changes from year to year based on the climate.
For instance, a warmer summer may push the boundary further up the ice sheet, whereas a colder year may push it closer to the ice margins.
Snow that accumulates on the ice throughout the winter transforms into new ice over time, if it does not melt away during the summer.
To achieve balance for the ice sheet, the new mass must match the mass removed.
In a steady environment, this is true, but a hot summer causes the snow layers to melt away.
This snow will be absent from the mass budget for many years, producing an imbalance.
Using a rigorous glaciological theory, the researchers determined the average snow line required to restore equilibrium to the ice sheet.
In the best-case scenario, their findings indicate that a minimum of 3.3% of the Ice Sheet will be destroyed, which is equivalent to 110 million tonnes of ice or a sea level rise of 10 inches (27cm).
Professor Box remarked, “It is an extremely conservative bare minimum.”
Realistically, this number will more than double during the next century.
The researchers examined solely the Greenland Ice Sheet and did not consider sea level increase caused by Antarctic ice melting.
In the past, climate models have been used to estimate the rise in sea level, but this is the first time that experts have developed estimates based on data.
According to Professor Box, this drastically unorthodox strategy has raised eyebrows in the scientific community.
“In this region, the ice flow models are not yet complete,” he explained. This is a method of determining mass loss that was previously lacking.
The disadvantage of this strategy is that it does not provide a time frame.
“To arrive at the number we have, we have to exclude time from the equation,” Professor Box explained.
Our data indicate that the majority of the projected sea level rise will occur in this century.
