Researchers used visitation, heat-related illness, temperature and humidity data at the Grand Canyon over a six-year period from 2004 to 2009 to determine a heat-illness risk baseline, and then used climate models to predict how that risk would change in the future under two scenarios: a moderate and high increase of planet-warming pollution. They found the rate of heat illness per 100,000 visitors increased across both scenarios.
Buttke said the study’s heat illness projections could be underestimated because current warming and emissions “closely track” to the worst-case scenario and visitation could go up and put more people at risk. The heat illness data used in the study only took into account people treated in the park and not those who didn’t seek treatment or sought it elsewhere. “It’s possible these are underestimates because we’re already at the upper level of what our model projects,” Buttke told CNN.