When I posted that weather forecast for the Arctic in the Beaufort under early pressure blog post a few days ago and said very large anomalies are forecast for Greenland and Baffin Bay, it didn't really occur to me just how exceptional that temperature anomaly was going to be for Greenland and its ice sheet*. Now I know.
A bell started to ring softly today while reading this blog post by Robertscribbler, in which he describes the temperatures and wind speeds that hit Greenland yesterday. But things really hit home when I read this news article on Polar Portal, written by Dr. Ruth Mottram from the Danish Meteorological Institute:
Unusually Early Greenland Melt
An early melt event over the Greenland ice sheet occurred this week, smashing by a month the previous records of more than 10% of the ice sheet melting.**
Left: Maps showing areas where melting has taken place within the last two days. Right: The percentage of the total area of the ice where the melting occurred from January 1 until 11th May (in blue). The dark grey curve represents the 1990-2013 average. The grey shaded area represents the year to year variation for each day.
Based on observation-initialized weather model runs by DMI, almost 12% of the Greenland ice sheet had more than 1mm of melt on Monday 11th April, following an early start to melting the previous day. Scientists at DMI were at first incredulous due to the early date. “We had to check that our models were still working properly” said Peter Langen, a climate scientist at DMI. “Fortunately we could see from the PROMICE.dk stations on the ice sheet that it had been well above melting, even above 10 °C. This helped to explain the results”. The former top 3 earliest dates for a melt area larger than 10% were previously all in May (5th May 2010, 8th May 1990, 8th May 2006).
“Even weather stations quite high up on the ice sheet observed very high temperatures on Monday”, said Robert Fausto, a scientist at GEUS who maintains PROMICE.dk melt data. “At KAN_U for example, a site at 1840 m above sea level, we observed a maximum temperature of 3.1°C. This would be a warm day in July, never mind April”. Other PROMICE stations in the network at lower levels had daily average temperatures between 5 and 10 °C.