Over the past week, hundreds of thousands of people in France and Spain fled their homes, many in the dead of night, carrying only what they could. In the coming days and weeks, as evacuation orders lift, some will come home to partially destroyed towns. Others will only find ash.

The fourth heat wave of a broiling summer is underway this week, and Europe has already seen one of its most destructive wildfire seasons on record, leading to one of the largest evacuation of people on the continent since World War II. It’s also the latest consequence of climate change, according to a study released on Thursday by World Weather Attribution, a scientific nonprofit that analyzes the role of global warming in extreme weather events. Human-induced climate change made the likelihood of fire-prone conditions in France at least twice as likely, and at least 20 times as likely in central Spain.

“This is not an isolated event, it is part of a pattern,” said Maria Alcazar Castilla, the deputy regional director of the International Federation of Red Cross in Europe. The Red Cross is helping coordinate the disaster response effort in both countries and providing supplies and temporary shelter for thousands.