Summer doesn’t begin for two more days, but scientists are already sounding the alarm about dangerous ice melts going on right now in Greenland.

The vast island usually locks away enough fresh water in its ice sheet, which if melted can raise global sea levels by six meters. And research shows that in recent years its ice has melted faster than ever before. This month, as temperatures in northwestern Greenland approach all-time highs, researchers are encountering unusual, surprising levels of melting ice in the region.

The most significant concern here is how early this is all happening. Greenland experiences annual ice melt and growth cycles. But this year, the melting season began in early May. That’s a month earlier than normal and something that’s happened only once before in the historical record in 2016.

That means that not only is the ice melting very fast, it has more time to melt this summer than it would in a normal climate system. Longer melt seasons like this one seem to lead to much greater contributions to sea-level rise than in previous decades.