Far above us, in the stratosphere, the world’s ozone layer protects people and natural systems from the sun’s harmful ultraviolet rays. Much of the life on Earth has adapted to live under this protection. In the twentieth century, as society developed new technologies, especially refrigeration and cooling, we released chemicals that traveled to the stratosphere and depleted some of this stratospheric ozone, creating expanding “holes” through which protection did not occur. With the use of these chemicals growing rapidly, projected damage to the ozone layer posed an existential threat to humanity.

In 2019, I was invited to give a TED Talk on emergency medicine for climate. In the five years since, climate extremes have escalated in the US and around the world — from Bangladesh to Brazil and Phoenix to Florida — with June breaking more than 1,000 temperature records around the world. As the world warms unusually quickly, these record extremes are accelerating changes in natural systems and devastating people and communities.