Heat and Wildfires Are Increasingly Straining the Earth’s Atmosphere

Wildfire smoke has become a major source of air pollution, and extreme smoke events have tripled since the 1990s, according to a new report from the World Meteorological Organization.

The report highlights how fires and climate change are undoing progress in cleaning the air. The consequences extend beyond the areas where fires burn, with pollution spreading across borders and affecting health.

When forests burned in Canada in the summer of 2025, research aircraft and monitoring stations tracked a plume of particles and carbon monoxide across half the globe. The pollution reached the upper troposphere, where high-altitude winds carried it onward. It was later detected over Europe and the Mediterranean.

The same pattern emerged this year after extensive fires in the Canadian wilderness. Smoke from vegetation fires, including those in Portugal’s Mirandela region, is no longer a local problem. It has become a significant source of atmospheric pollution.