25th of March, 2021. Part of the Topos Institute Colloquium. ----- Abstract: The climate crisis is part of a bigger transformation in which humanity realizes that the Earth is a finite system and that no physical quantity can grow exponentially forever. This transformation may affect mathematics — and be affected by it — just as dramatically as the agricultural and industrial revolutions did. After a review of the problems, we discuss how mathematicians can help make this transformation a bit easier, and some ways in which mathematics may change.