Competing effects of vegetation on summer temperature in North Korea

Vegetation reduction could affect regional climate by perturbing the surface energy and moisture balances via changes in albedo and evapotranspiration. However, it is unknown whether vegetation effects on climate occur in North Korea, where a severe reduction in forest cover has been observed. This study aimed to identify the biogeophysical processes in vegetation and climate interactions in North Korea, using the Normalized Difference Vegetation Index (NDVI) from the AVHRR GIMMS NDVI3g and the climate reanalysis data from the ERA5-Land over the period of 1982‒2015. As per the NDVI regression trend results, the highest rates of decreasing NDVI (10–20%/decade) were detected in the western region of North Korea during the summer. Based on the detrended correlation analysis of NDVI with surface energy variables at each grid point, including solar radiation, sensible and latent heat fluxes, Bowen ratio, and temperature, we identified the distinct biogeophysical effects of vegetation between the western and northern regions of North Korea. In the western (northern) region, a cooling (warming) effect of vegetation on the local temperature was approximately by 0.2–0.3 °C/0.1 NDVI during the summer. The competitive biogeophysical effects were induced by the geographical factors of relatively lower (higher) values of NDVI, altitude, and latitude in the western (northern) region. Particularly, if the current rate of deforestation continues, the increasing summer temperature would be up to 0.5 °C by the end of this century in the western region of North Korea, where large-scale human-induced forest loss has been observed. Thus, we urgently suggest that sustainable management and restoration of forests are needed in North Korea, which is among the countries most vulnerable to climate change now and in the future.