Our goals in life as a Jew are the same no matter what: Keep all the mitzvot, improve our midot, learn as much as we can so we can do a better job at both. That is true whether or not the earth is warming or cooling. (And in fact it is warming.)
That doesn’t mean that there are times that the events of the world don’t demand action. For an obvious example, every Jew should have gotten out of Germany in 1938. For only a slightly less obvious example, we should all encourage each other and our non-Jewish neighbors to use less energy so that anti-Semitic Arabs and the Venezuelan Rasha don’t get as much of our money.
Others will be able to come up with other actions, but the Rabbi was basically right!