Who bears the income cost of extreme heat? Adaptive inequality in china's urban and rural labor markets

Extreme heat is becoming a labor-market risk, but its distribution across workers remains insufficiently understood. This study examines whether recent wet-bulb globe temperature (WBGT) exposure is associated with an annual-income-based hourly earnings proxy and whether this association differs between rural and urban workers in China. We link 726,480 person-wave observations from the China Family Panel Studies (2010-2022) to prefecture-level (European Centre for Medium-Range Weather Forecasts Reanalysis v5) ERA5 -derived WBGT and estimate high-dimensional fixed-effects models with mutually exclusive thermal bins. The results show a monotonic heat-earnings gradient: one additional WBGT >33 C day is associated with a -0.074 log-point coefficient among rural agricultural workers and -0.031 among urban workers. Heterogeneity and descriptive accounting analyses show that vulnerability clusters around outdoor work, low income, limited cooling access, and occupational heat intensity. (Coupled Model Intercomparison Project Phase 6) CMIP6 scenario calculations indicate that, under current adaptation assumptions, rural-urban earnings vulnerability may widen in high-emissions futures. The paper contributes an adaptive inequality framework that separates biophysical work-capacity constraints from labor-market realization and treats hourly earnings as an earnings-based proxy rather than direct physical productivity.