Credit: The 79° N Glacier, Greenland’s largest floating glacier tongue. On the one hand, this sudden drop in temperature is a welcome relief for the Greenland glacier that could keep it from melting away anytime soon.
Keeping the Glacier’s Meltwater Cool
One of the largest floating glacier tongues in the world, the 79° N Glacier has been under intense pressure from climate change. The glacier is being melted from below by warm water recently found to be eroding 17 of Greenland’s glaciers, which may only add to the overall problems seen as afflicting what is known as the Greenland Ice Sheet.
Yet a new paper published on 13 December in Science shows that things are not quite so simple. Despite more than a century of ocean warming, the temperature of the water entering the glacier’s cavern dropped between 2018 and 2021 according to researchers from the Alfred Wegener Institute.
This brief cooling effect is the result of abrupt shifts in atmospheric circulation patterns a phenomenon known as ‘atmospheric blocking. Located above Europe, the stationary high-pressure systems have drawn more cold air from the Arctic through increasingly warming oceans across the Fram Strait and into the Norwegian Sea, essentially throttling a now-typical warm Atlantic flow toward the glacier. This cold water then reached 79° N glacier and helped cool the melting at its base.
Future Prospects for Greenland’s Glaciers
The researchers explain that these atmospheric blocking events are expected to remain a major contributor to the variation in future temperatures of the Atlantic Ocean water that reaches Greenland’s glaciers.
The near-term cooling had slightly decelerated the melting of the 79° N Glacier in recent years, “but it is too soon to say how long that might last,” said Andresen. The researchers found that the Greenland Ice Sheet already lost some mass, mainly due to warming of the atmosphere and oceans and noticed that only the Northeast Greenland Ice Stream could alone give as much as one meter of sea-level rise if it melted entirely away.
The scientists highlight the necessity of continuous monitoring efforts that can observe and describe what influences glacier movements in Greenlanders by changes in large scale ocean circulation. This will be important for honing predictions about the fate of this crucial ice in advance of their role feeding global sea level.
Conclusion
At the same time, this unexpected observation — a detour of atmospheric flow slowing melt of one part of Greenland — may provide little comfort considering the overwhelming evidence that this ice and with it most glaciers along the semester have been steadily in retreat for decades due to an ongoing shifting climate. Further monitoring and research are needed to explain this coupling between the atmosphere, ocean, and ice sheets and to improve future predictions of changes in sea level under a changing climate.
