Park is a hydroclimatologist whose research aims to understand the causes and consequences of hydrological extremes such as drought. Much of his research focuses on hydroclimatology in its own right, and much also aims to improve understanding of how hydrological extremes affect life on earth (bioclimatology). Questions that he finds especially interesting involve the effects of human-caused climate change on the hydrological cycle, ecological systems, and humanity through extreme events such as heat waves, wildfires, and flooding.