The basis of the marine food web in the Arctic, the phytoplankton, responds to heatwaves much differently than to constantly elevated temperatures. This has been found by the first targeted experiments on the topic, which were recently conducted at the Alfred Wegener Institute’s AWIPEV Station. The phytoplankton’s behaviour primarily depends on the cooling phases after or between heatwaves, as shown in a study just released in the journal Science Advances.