As average temperatures rise, the specific climate conditions a given species is adapted to don't simply disappear — they shift, generally moving toward the poles or toward higher elevation, where cooler conditions still persist. Some species can, in principle, track that shift by gradually moving their own range along with it, generation after generation. Climate change ecology studies exactly this process, and crucially, studies why many species genuinely can't do it — either because they physically disperse too slowly to keep pace with how fast the climate zones themselves are shifting, or because there's simply nowhere left for them to go.
Tracking a shifting climate requires moving faster than the shift itself
For a species to successfully track a shifting climate zone by relocating its range, its own rate of dispersal — how far individuals or populations can realistically spread into new territory over a given span of time — has to keep pace with how quickly the suitable climate zone itself is actually moving. Species that disperse slowly, for reasons that can include limited mobility, a need for a very specific habitat that isn't uniformly available across a wider area, or a long time between generations, risk being left behind as the climate conditions they're specifically adapted to move on without them, effectively trapping the slower species in conditions that are steadily becoming less suitable for it even as, elsewhere, the same conditions it needs re-establish themselves further away.
Elevation-adapted species can eventually run out of mountain
Species already adapted to cooler conditions found at higher elevation face a distinct and, in an important sense, more absolute version of the same basic problem: as temperatures rise, they can initially respond by shifting their range further upslope, toward the cooler conditions still available higher up a mountain. But a mountain has a literal, physical summit, and a species that's already living near the top of the highest elevation available to it in a given region has nowhere higher left to retreat to — a phenomenon ecologists sometimes describe as being pushed toward, and potentially off, a mountain's summit, since further warming leaves no remaining higher, cooler ground the species could otherwise shift into, unlike a species with open lower-elevation land still available to it in the direction climate zones are shifting.
What we're still unsure about
The basic mechanisms of range shifting, and the genuine limits some species face in dispersal ability or available higher ground, are well documented across a large and growing body of ecological research. What remains harder to predict with real precision is exactly which specific species, in which specific ecosystems, will actually be pushed toward local extinction by these dynamics within a given future timeframe, since a species' real-world fate depends on a complex combination of factors — its own dispersal capacity, the availability of suitable habitat corridors connecting its current and future range, and how it interacts with other species that are simultaneously shifting their own ranges at different rates — that researchers are still working to model accurately for the very large number of species climate change potentially affects.
This sits inside Climate Change Ecology, one of seven topics in Ecology, one of six domains in Biology, one of seventeen subjects the app can quiz you on.