As we pour heat-trapping gases into the air, we’re running an experiment. We’re going to see what a rapidly changing climate does to the world’s biodiversity — how many species shift to new ranges, how many adapt to their new environment and how many become extinct.

We don’t have a very good idea of how the experiment will turn out. Scientists are coming to appreciate that there’s a lot about how climate affects life that they still don’t understand. That’s true, it turns out, even for species that scientists have been studying carefully for years.

In the early 2000s, Ary A. Hoffmann, a biologist then at La Trobe University in Melbourne, Australia, wondered how the many species in tropical rain forests would cope when their humid environment dried out.

It was conceivable that some species might adapt. Over the generations, natural selection ought to favor the individuals that could survive longer in dry air. Over time, the whole population should become more resistant.