A forest service fire danger sign next to Highway 191 in West Yellowstone, Montana, warns the fire risk is ‘very high’. ‘At least over the next few decades, we are going to see these recurring really large, catastrophic wildfires,’ Dr Ben Cook, a Nasa climate scientist, says of the western US. ‘You’ll have good years, and you’ll have bad years, but climate change is leading towards a trend of more area burned every year’