“My starting point today is the growing threat of climate change. Tackling this challenge is crucial if we want to ensure that the Arctic remains the place it is today. But the issue is of global significance: If we lose the Arctic, we lose the whole world.” Sauli Niinisto,President of Finland
The Greenland ice sheet endured one of the biggest melt events on record; the heatwave peaked on the thirty-first of July, where enough melt-water was generated that it could cover Florida in five inches of water. It was a massive loss of ice volume on the very vulnerable ice stream. It was not the largest event; 2012 was the largest, and 2019 holds a close second. In an interview with Accuweather, Ruth Mottram, a Greenland scientist, noted that these heat events were quite rare before 2000 since then events occurred in 2002, 2010, 2012, 2019, and now 2021 (x2).
In a tweet today, climatologist Xavier Fettweiss expects the 2012 and 2019 records to be shattered on or around this weekend with temperature anomalies of 34.5 degrees Fahrenheit accompanied by heavy rain. Rain causes the ice to melt quickly. In the higher elevations, the rain will freeze. For the rest of the ice sheet, the ice melt has a likely chance of emptying into the Arctic ocean. Aggravating the AMOC even further.
Greenland rainfall events even happen in winter.
This video of sled dogs running through the 2019 melting event is haunting.
In 2012, when Greenland had their first dramatic melt across the whole ice sheet, it was unexpected. That wasn’t in the models for decades to have anything like that. Now that has become pretty commonplace. Harold Wanless, Department of Geological Sciences - University of Miami
Over the forty-year period 1981–2010, the model simulates increases in both rainfall and rainfall intensity, across the ice sheet and especially in late summer. We specifically find that total September rainfall increased by 224% over this period. The maximum intensity of September rainfall also increased by 54% during this same period. This is consistent with the expectation that the summer melt season will lengthen and intensify in a warming climate. Some of the most pronounced increases in rainfall were seen in Northwest Greenland. There, the rainfall fraction of precipitation is about twice the ice-sheet average. We speculate that this increasing trend in rainfall in Northwest Greenland may be related to a northward shift in the limit to which relatively warm and moist mid-latitude airmasses can penetrate each summer.
A large rainfall event can have a similar influence on ice dynamics as a large melt event. Once liquid meltwater enters the ice sheet, flowing in the en- and sub-glacial hydrology systems, there are myriad of ways it can make ice flow faster. Chief among these is warming and softening the ice (so the ice internally deforms and flow more easily) and pressurizing the subglacial hydrology system (so the ice-sheet slides more easily). For this reason, there is also an ice dynamic interest in big rainfall events. Some of the most pronounced increase in extreme rainfall events (i.e. >5 cm per hour) were in South Greenland. There, the ice sheet is most exposed to mid-latitude storms from the North Atlantic. There is an expectation for the intensity of storms to increase in a warming climate.
We will probably hear a lot more about rainfall on the Greenland Ice Sheet in the coming years. Hopefully, once some of the technical challenges are overcome, we will start to see the systematic collection of continuous rainfall measurements on the ice sheet. Given our current climate trajectory, we will also start to see rainfall comprising a larger portion of the annual ice-sheet water budget, especially in ice-sheet basins in South Greenland. There are already several studies linking rainfall events to ice motion at lower elevations, but presumably these links will also start to be made at higher elevations. There is a lot of research to do on the topic of ice-sheet rainfall!
Like in Siberia and the Arctic Ocean, once climate change damages the ecosystem, the extraction industry moves in to gobble up its resources.
Dr. Jason Box of the Geological Survey of Denmark and Greenland is always worth listening to. I hope that the scientists are on the cable channels speaking on climate and not political commentators one day.
Water is life! Climate change is a planetary problem, and it is a racist problem. Here is how you can help.