It’s well known that hotter temperatures due to climate change are dangerous to human health. But when paired with high humidity, this intense heat can be especially deadly. These extreme weather events, known as humid heat waves, are rapidly intensifying and increasing in frequency as the world warms.A recent study found a strong causal link between hotter coastal ocean temperatures and large-scale humid heat waves. Rising sea surface temperatures are driving 50-64% of the increase in large-scale humid heat waves, researchers found, especially in the tropics, and raising the risk of heat-related fatalities.These events do not remain localized. The researchers found that coastal humid heat waves can move far inland, and have a 90% chance of occurring even 1,000 kilometers (620 miles) away from where they originated over the ocean.Humid heat waves now pose a serious risk to people in tropical regions, though such events are forecast to worsen in temperate zones too as the world warms. Adding to threats in the tropics is insufficient air-conditioning to safeguard populations against such events. Humid heat waves also make outdoor work unsafe, impacting local economies.
As climate change intensifies, people around the world are learning firsthand how dangerous high temperatures can be. But prolonged heat becomes even more dangerous, and deadly, when paired with high humidity — a one-two punch known as a humid heat wave.
