Now experts have examined the level of melting in more detail, revealing what drove it. Crucially, the team note, the high pressure conditions lasted for 63 of the 92 summer days in 2019, compared with an average of just 28 days between 1981 and 2010. A similar situation was seen in 2012, a record bad year for melting of the ice sheet.
The team say the climate models of the Intergovernmental Panel on Climate Change (IPCC) have not taken into account such unusual conditions. If such high pressure zones become a regular annual feature, future melting could be twice as high as currently predicted, a result that could have serious consequences for sea level rise.