Scientists say that the loss of ice in Greenland progressed again last year, breaking the previous record by 15%.
A new analysis says that the scale of the melt was “unusual” in records dating back to 1948.
High pressure systems that were blocked across Greenland last summer were the direct cause of the enormous losses.
But the authors say that continuous emissions of carbon are pushing Greenland into a period of more extreme melts.
Over the past 30 years, Greenland’s contribution to global sea levels has grown significantly as ice losses have increased.
A major international report on Greenland released last December concluded that it was losing ice seven times faster than it was in the 1990s.
Today’s new study shows that trend continues.
Using data from the Grace and Grace-FO satellites, as well as climate models, the authors conclude that Greenland lost 532 gigatons of ice in the whole year – a significant increase in 2012.
The researchers say the loss is the equivalent of adding 1.5mm to global average sea level, about 40% of the average increase in one year.
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Steffen Olsen
Climate scientist Steffen Olsen took this photo when he traveled over melted sea ice in Northwest Greenland in 2019
According to a calculation by Danish climate scientist Martin Stendel, the losses of 2019 would be enough to cover the entire UK with about 2.5 meters of meltwater.
Both last year and 2012 were marked by “blocking” events, the researchers say, where disruptions in jetstream high-pressure systems were seen spreading across Groningen, resulting in improved melting.
“We seem to have entered an empire of more and more extreme melts in Greenland,” said lead author Dr Ingo Sasgen, of the Alfred Wegener Institute in Bremerhaven, Germany.
“It is expected that something like the years 2019 or 2012 will be repeated. And we do not know exactly how the ice behaves in terms of feedback mechanisms in this violent meltdown area.”
“There could be … hidden feedback that we are not aware of or that may not have been perfectly described in the models at the moment. That could lead to some surprises.”
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While 2019 broke the record, both 2018 and 2017 saw ice losses, lower than any other two-year period since 2003.
The authors say this was due to two very cold summers in Greenland followed by heavy snow in the autumn.
However, returning to high levels of melting in 2019 is a major concern. Five of the years with the largest mass loss have now occurred in the past decades.
“What really matters is the trend,” said Dr Ruth Mottram, of the Danish Meteorological Institute in Copenhagen, who was not involved in this new study.
“And that trend as reflected through the Imbie (Ice Sheet Mass Balance Inter-Compare Exercise) project and other work is following the high end of projections.”
Although 2020 has so far seen average conditions in Greenland, the overall impact of the massive ice loss in recent years could have major implications for people living in low-lying areas of the world.
“The result for 2019 confirms that the ice sheet is back in a state of high loss, in line with the IPCC’s worst-case climate warming scenario,” said Leeds University professor Andy Shepherd, co-lead researcher for Imbie .
‘This means we need to prepare for an extra 10cm or so of global sea level rise with 2100 from Greenland alone.’
“And at the same time, we need to invent a new scenario in least cases, because Greenland is already following the current one.”
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“If Greenland’s ice loss continues on its current trajectory, an additional 25 million people could be flooded each year by the end of this century.”
Recent media reports have suggested that Greenland may have reached a point of no return, that the level of global warming that the world is already craving for carbon emissions means that the whole of Greenland will melt.
Dr Sasgen says this perspective may be correct – but the fate of Greenland is still in our hands.
“The sea level rise rates we expect from Greenland, and the risk of sudden sea level rise from Greenland will be drastically reduced if we stay below warming limits,” he said.
“The report from home is that if we reduce CO2, and we reduce or limit global warming, then the risk of huge contributions from Greenland will also be reduced in the very future.”
The paper was published in the journal Nature Communications Earth & Environment.
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