May’s temperatures broke global records yet again, as the northern hemisphere finishes its hottest spring on record, statistics released by NASA showed. The Arctic in particular experienced abnormal heat, causing Arctic sea ice and the Greenland ice sheet to start melting unusually early.

Alaska recorded its warmest spring on record by a wide margin, and in Finland the average May temperature was between three and five degrees warmer than usual in most regions, according to data from the Finnish Meteorological Institute. The El Nino weather pattern factored into 2016’s record-setting heat, but meteorologists say greenhouse gases emitted from human activities remain the underlying cause.

Austraila’s Bureau of Meteorology blamed warm waters for “unprecedented” bleaching of the Great Barrier Reef. The US National Oceanic and Atmospheric Administration (NOAA) is expected to announce complete global May temperature records in the coming days.

Recent predictions by US scientists anticipate that 2016 will go down as Earth’s hottest year on record—on the heels of record-setting years in 2014 and 2015. In late May, NOAA announced that April also registered its highest temperatures ever, marking the twelfth consecutive month of record heat.