Greenland’s ice sheet has begun melting much earlier than usual – nearly three weeks earlier than the previous record, according to the Danish Meteorological Institute (DMI).

Almost 12% of the Greenland ice sheet had more than 1mm of melt, as of Monday 11 April. The previous records for a melt area over 10% were all in May – the earliest on 5 May 2010. In an article for Polar Portal, a platform for Danish research institutes to share their findings, the researchers said they couldn’t believe the results.

“We had to check that our models were still working properly,” said Pater Langen, a climate scientist at DMI.

Image: DMI/Polar Portal

This map from the institute shows the melting from Sunday 10 April to Monday 11 – highlighting the increase across 24 hours. The chart on the right tracks the normal melting period for the ice. The percentage of the melt is plotted against the months of the year, with the dark grey line representing the average, while the shading is the year-to-year variation for each day.

The chart emphasizes the exceptional nature of Monday’s melting, with a level of melt comparable to the May or June average.

Why has it happened so early?

Greenland is experiencing a period of unseasonably warm weather. A site 1,840 metres above sea level recorded a temperature of 3.1 degrees Celsius on 11 April. That might not sound like much, but scientists explain that for such a level of elevation that temperature is more usual for a warm July day.

Lower coastal areas experienced near record temperatures as well. As Martin Stendel, a climate scientist at DMI explained, “it is a very unusual situation, especially so early in the year”.

Temperatures are expected to cool again, but this early melt indicates that future melting this year will start at lower temperatures. This is because when melted ice runs into snow and refreezes, it heats up the ice beneath.

Is global warming to blame?

February 2016 was the hottest month on record, according to NASA data. Global surface temperatures were 1.35 degrees Celsius above the long-term average, beating the previous record, which was January.

Image: NASA/GISS

While acknowledging the impact of specific climate events such as El Nino, scientists also emphasized the impact of greenhouse gas emissions on global temperature increases.

So, although this melting is directly linked to a period of exceptionally warm weather, carbon emissions and climate change are probably playing a significant background role.