It's not one many people think about, mostly you think about extreme weather events like droughts and floods and so forth. As the climate changes though, species that are well adapted to a particular type of climate, move. The cooler an animal needs to be, the further towards the poles it will travel. This, of course, has to be balanced with if the species can still find food or water or whatever else it needs in it's new location. So it's entirely possible that species will attempt to move and die or won't be able to move and die. A number of species will probably be able to survive but will move from flourishing to bare survival. Given the breakneck speed (evolutionarily speaking) there's no time for species to adapt to the climate as it changes around them. If you were particularly macabre, you could probably use the disappearance of species as a substitute for a thermometer.