Indonesia has long suffered from forest fires during the annual dry season. Many are set deliberately, by farmers and firms clearing land for crops such as oil palm. The blazes have grown more serious as agriculture has expanded onto peatlands, which become volatile when drained. This year’s El Niño has lengthened and intensified the dry season, creating a calamity. A reeking white mist which caused school closures and flight cancellations in Singapore and Malaysia has spread as far as Thailand and the Philippines. Data from Guido van der Werf, a Dutch researcher, suggests the emissions from this year’s fires have caused Indonesia to surpass Japan as the world’s fifth biggest polluter.