Data from the Danish Arctic monitoring service Polar Gate – agency that forms part of the United Nations weather agency WMOannual Climate status reported – shows a cold and wet early summer, with unusually heavy and late snowfall in June, which delays the start of the thaw season.
However, after that, a heat wave at the end of July caused a significant amount of ice loss.
In terms of “total mass balance” (the sum of surface ice melt and ice loss from the icebergs, in addition to the melting of the glacier “tongues” in contact with seawater), the ice sheet lost about 166 billion tons during the 12-month period ending in August 2021.
Polar Gate
The difference between the annual surface mass balance for the periods 2010-2021 and 1981-2010 (expressed in mm of melting ice).
Climate change
These numbers mean the iceberg ended the season with a net surface mass of about 396 billion tonnes, making it the 28th lowest on record, in a 41-year time series.
This can be seen as an average year, but Polar Report notes how views have changed, given that climate change is happening rapidly.
For example, in the late 1990s, these same numbers would be considered a year of very low surface mass balance.
The report also notes that the cause of the early summer cold is likely due to conditions in southwestern Canada and the northwestern United States.
In these territories, a huge “barrier” high-pressure system was formed, shaped like the capital letter Omega (Ω) in the Greek language.
Polar Gate
The map shows cool, wet summer weather over Greenland (in the center of the map) and extreme temperatures over North America.
This flow pattern occurs frequently in the troposphere, and not only in North America, but it has never been observed with such magnitude before.
According to the report, an analysis by World Weather Attribution demonstrated that it can only be explained by warming of the atmosphere caused by human activity.
Notable year
According to the report, 2021 is notable for a number of reasons.
That was the year when the rainfall at Summit Station, which sits atop the iceberg at 3,200 meters above sea level, was recorded as rain.
The year also saw an acceleration of ice loss at the Sermeq Kujalleq glacier, where the rate of loss has stagnated for several years.
Winter snowfall is also close to the 1981 to 2010 average, which is good news, as the combination of low winter snowfall and warm summers can lead to higher amounts of snowfall. Huge ice loss, as was the case in 2019.
© WMO / Karolin Eichier
In Greenland, the melting of the ice sheets is accelerating.
