Unequal exposure to heatwaves as seen from space: a case study in Los Angeles

Cities are at the front line of growing climate change risks. Hence, it is increasingly important to understand heat exposure experienced by different communities in urban areas where the built environment amplifies extreme heat. The satellite ECOSTRESS measures land surface temperature at a high-spatial resolution of ~70 m; its unique diurnal sampling with ISS orbit allows us to gain more insights into the temporal variations in urban heat distribution. Focusing on the case of Los Angeles as an example, we find strong negative correlations between land surface temperature and neighborhood median household income. The disparities are largest in summer mid-day and increase as a function of the mean surface temperature across the city. The higher heat exposure in lower-income neighborhoods is predominantly induced by lower evapotranspiration from vegetation due to unequal distribution of green landscape. By altering the surface albedo through civil engineering, this inequality could be partly mitigated in the short term, while planning for green zone and landscape greywater recycling could improve equity in the long term.