Impact of land-use and land-cover changes on CRCM5 climate projections over North America for the twenty-first century

Abstract

The aim of this study is to assess the impact of land-use and land-cover change (LULCC) on regional climate projections for North America. To this end, two transient climate change simulations, with and without LULCC, but identical atmospheric forcing, are performed with the 5th generation of the Canadian Regional Climate Model (CRCM5) driven by CanESM2 model for the (2006–2100)-RCP4.5 scenario. For the simulation with LULCC, land-cover data sets are taken from the Global Change Assessment Model representing the RCP4.5 scenario for the period 2006–2100. LULCC in RCP4.5 scenario point to significant reduction in cultivated land (e.g. Canadian Prairies and Mississippi basin) due to intense afforestation. Results suggest that biogeophysical effects of LULCC on climate, assessed through differences between the all-forcing (atmospheric and LULCC) run and the atmospheric forcing run (with constant land cover) are substantial for relevant surface variables. It is shown that the afforestation of cropland lead to warmer regional climates, especially in winter (warming above 1.5 °C), as compared with climates resulting from atmospheric forcings alone. The investigation of processes leading to this response shows high sensitivity of the results to changes in albedo as a response to LULCC. Additional roughness, evaporative cooling and water soil availability also seem to play an important role in regional climate especially for the summer season in certain afforested areas (e.g., southeastern US).