Many species of animals are evolving slowly to cope with higher average temperatures.

That's fine as long as they can keep up. But as global heating speeds up, more and more species will lag behind and die out.

Meanwhile, there are hard limits to cope with. Small adaptations may not enable humans to survive a fatal heat-humidity combination. As long as we depend on evaporation to cool our bodies, it will be effective only when the ambient air causes evaporation.