My short answer is it depends on the species, and it depends on the communities of species we're talking about. For example, in our aquatic ecosystems, yes, temperatures are incrementally rising, just as they are in terrestrial ones. In the province of Ontario, over the last 80 years, about three degrees Celsius has been documented.
The point is, that will favour some species, whether they be animal or plant species; it will provide an advantage to them. But it will provide a disadvantage to other species.