They've also been widely used within the geosciences for about 40 years. We refer to gaussian process regression as "kriging" (after the originator if the metho

They've also been widely used within the geosciences for about 40 years. We refer to gaussian process regression as "kriging" (after the originator if the method) and classification as "indicator kriging", but it's the same method. If you've ever heard anyone refer to what they're doing as "geostatistics", they were almost definitely doing a regression problem using gaussian processes.