In the boreal summer of 2021, as heat extremes triggered mass death in ecological systems, pushed engineered systems to the breaking point, and threatened health and well-being of people across the northern hemisphere, it was impossible to ignore the intensifying nature of summertime heat. This, coming in the same months as deadly flooding and historically intense fires in multiple countries, is both alarming and profoundly unsettling. As Amitav Ghosh wrote of climate extremes: ‘they are the mysterious work of our own hands returning to haunt us in unthinkable shapes and forms’ [1]. The summer of 2021 met this vivid description. It was also a preview of greater extremes to come and an indicator that even wealthy communities are poorly prepared to reduce harm from extreme heat under climate change.

Understanding and preparing for these intensified heat extremes requires transdisciplinary collaboration across diverse communities, sectors, and fields of research. Here we highlight the powerful role that satellite-derived Earth observations (EOs) can play in these efforts. In the context of the 2021 heat extremes, we consider EO contributions in four areas: monitoring, attributing, projecting, and adapting to extreme heat events.