Global warming is the prime existential issue facing our planet. Accordingly, there can be no greater public health concern than the need to maintain economic activity while protecting workers directly exposed to solar radiation. Since mining, agriculture, construction, and sport and recreation inevitably involve solar exposure, climate change portends a decreasing number of days and hours when workers in these industries can be both productive and free of risk of heat illness. The implications are especially profound in those parts of the globe where humidity levels are predicted to exceed the limits of human tolerance.