THE fires are blazing. The west of the United States has endured some 50,000 wildfires this year, and over 8.5m acres (3.4m hectares) have burned. …In Canada, as of August 30th (the latest available figure), 7.4m acres had burned. …Why have so many fires burned in North America this year? In terms of scale, 2017 is not actually an outlier. In the past decade, wildfires have burned an average of 6.6m acres each year in the United States and 6.2m acres in Canada. The particular problem this year is the dispersed nature of the blazes. In other years, the fires have clustered in a single state or province. This year, not only have the wildfires burned on more fronts, but they have done so closer to heavily populated areas. …The current state of the north-western forests, combined with the effects of climate change, increase the likelihood that wildfires will be worse in future.