For context, the planet has warmed ~2*F since ~1850. While global warming is surly a thing I certainly wouldn't rank it on a top 10 list of reasons diseases and microbes are created.
The primary threat is expansion of existing diseases. I wouldn't discount the temperature change so readily, one of the mechanisms was increased precipitation (as they noted in the case of Valley Fever, driven by the 'grow and blow' effect of wet and dry whiplash).