 The latest study shows that humid heat, based on a wider range of temperatures and humidity, is associated with over 650 billion hours of annual lost labour globally, which is 400 billion hours more than previous estimates. This represents 148 million full-time equivalent jobs lost, comparable to losses caused by the COVID-19 pandemic. The study also shows that global heat-induced labour productivity losses are estimated at 2.1 trillion in 2017 PPP$, and in several countries are equivalent to more than 10% of gross domestic product. Over the last four decades, global heat-related labour losses increased by at least 9%, highlighting that relatively small changes in climate, less than 0.5 degrees Celsius, can have large impacts on global labour and the economy. This article was authored by Luke A. Parsons, Eta J. Massouda, Tim Kroger, and others.