Monday saw the Greenland ice sheet covered in a record-breaking level of melt water for this time of year, according to scientists who monitor it.

Researchers at the Danish Meteorological Institute found that a whopping 12% of the ice sheet was covered in a layer of melt water that was at least 1 millimeter thick. Such double-digit figures typically don’t emerge until May – and the day before had seen levels of only 4%.

The numbers had some researchers feeling “incredulous,” according to an update posted on Polar Portal, a collaboration among several Danish research institutions.

“We had to check that our models were still working properly,” Peter Langen, a climate scientist with the meteorological institute, said in the update.

Source: Los Angeles Times