Fig. 5: Standardized coefficients of MLR models between socioeconomic variables and UVI trends in different climate zones.

R2 of the MLR models is presented in the upper left corner. Regression coefficients are marked as dots, while the bars represent the 95% confidence intervals (CIs), and significant variables are shown in red (p < 0.05). In the arid zone, as there was a strong multicollinearity between the Hispanic and White population (VIF > 5), we excluded the predictor of the White population based on a stepwise MLR and the Akaike information criterion index (Supplementary Table 3). ALL: four climate zones (a); Arid: arid zones (b); Tem: temperate zones (c); Snow: snow zones (d).