Welcome to Degrees of Change, I am Callum Reid. This week starts with heat, but not the usual way. Several cities have switched to a new heat index for issuing warnings, and it measures something that plain temperature misses. I will explain what it is and why it might save lives this summer. Then insurance, which is becoming the quiet front line of all this: several insurers have withdrawn from a flood-prone region, and I will walk through what that does to house prices and to the families who cannot move. And I want to spend real time on a small study about urban trees, because small does not mean weak when the method is good. An engineer joins me on cooling a bus shelter cheaply, and we end with the prediction ledger. You are listening on Witspeak Podcasts.