When the Term "Heatwave" Is No Longer Enough

A major investigative project argues that "heatwave" no longer captures the scale and behavior of current extreme-heat events and proposes the term "heat storm" for episodes of abnormally high temperatures that last at least five consecutive days and cover more than 1% of Earth’s surface. Historical analysis shows the planet averaged about five such events per year in the 1960s (the largest covering 6% of the surface and lasting 46 days), compared with an average of 102 per year today and recent events that at times affected as much as 85% of the globe. Scientists’ analysis finds that heat storms now cascade continuously - for 18 straight years at least one has been active - meaning much larger, longer, and overlapping episodes than the old "heatwave" framing implies.

The investigation pairs those findings with vivid human and ecological impacts: tens of thousands of excess deaths in Europe, glacier collapse in Nepal, heat-exhaustion hospitalizations in the U.S., mass die-offs of Amazon dolphins, and student nosebleeds in the Philippines. Those harms have emerged with only about 1.4°C of warming and are projected to worsen as temperatures reach roughly 1.7°C by midcentury unless emissions fall sharply, a gap the UN says is now "imminent and unavoidable" without massive mitigation. To improve public grasp and policy urgency, the project recommends naming heat storms much as hurricanes are named, a proposal some meteorologists question on technical grounds but many accept for its communicative power; activists and scientists already emphasize climate change as an emergency.