fact check
climate change
Is it true that Lake Constance could be filled almost 100 times with Greenland’s meltwater?
Icebergs near the coastal town of Ilulissat in western Greenland
© Ulrik Pedersen / Picture Alliance
The global sea level has already risen by 1.2 centimeters as a result of the ice melt in Greenland. Peanuts to the amount of water that would be released if the ice sheet completely disappeared.
Is it true that Lake Constance could be filled almost 100 times with Greenland’s meltwater?
It is true. Climate change is changing the world’s largest island. Its gigantic ice sheet is melting at a rapid, unprecedented rate: According to satellite data, it has lost 4,700 gigatonnes in the past 20 years alone. Lake Constance, which has a capacity of almost 50 gigatons, could actually be filled about 94 times with the meltwater.* It has caused the global sea level to rise by 1.2 centimetres. And that is just the beginning.
Because the Greenland ice sheet is considered the tipping point. The Earth’s ice sheets are slow to respond to climate change. However, once the melting is properly underway, it will not be stopped even if global warming is stopped in the future.
There is a simple mechanism behind this: glaciers lose height when they melt. However, because the air is colder higher up, as they shrink, their surface is exposed to increasingly warmer air – causing them to melt even faster.
Experts: Greenland’s ice sheet before critical transition
A tipping of the ice sheet would have dramatic consequences. Because it would significantly increase long-term global sea level rise. If the entire ice sheet disappears, the world sea level could rise by up to seven meters in the worst case. In Germany alone, around 3.2 million people live in areas on the North and Baltic Seas that are less than five meters above sea level.
In addition, the meltwater could alter the Gulf Stream, Europe’s hot water heating system. Like a giant conveyor belt, the system brings warm surface water from the equator north to the British Isles and off the coast of Norway, while simultaneously sending cold, low-salinity deep water back south.
Recently, scientists have discovered new early warning signs that the central-western part of the Greenland ice sheet could experience a critical transition relatively soon.
*: A commercially available built-in bathtub holds about 140 to 150 liters of water. The approximately 50 gigatonnes of water (50 billion liters) of Lake Constance correspond to the amount that would be needed to fill more than 333 million bathtubs.
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Swell: polarportal.dk / “Proceedings of the National Academy of Sciences of the United States of America” / Intergovernmental Panel on Climate Change (IPCC) / “Nature Communications” (1) and (2)/ German Bundestag