Abstract
This study investigates the biophysical impacts of human-induced land use change (LUC) on the regional climate of North America, using the fifth generation Canadian Regional Climate Model (CRCM5). To this end, two simulations are performed with CRCM5 using different land cover datasets, one corresponding to the potential vegetation and the other corresponding to current land use, spanning the 1988–2012 period, driven by European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA)-Interim at the lateral boundaries. Comparison of the two suggests higher albedo values, and therefore cooler temperatures, over the LUC regions, in the simulation with LUC, in winter. This is due to the absence of crops in winter, and also possibly due to a snow-mediated positive feedback. Some cooling is observed in summer for the simulation with LUC, mostly due to the higher latent heat fluxes and lower sensible heat fluxes over eastern US. Precipitation changes for these regions are not statistically significant. Analysis of the annual cycles for two LUC regions suggests that the impact of LUC on two meter temperature, evapotranspiration, soil moisture and precipitation are present year round. However, the impact on runoff is mostly restricted to the snowmelt season. This study thus highlights regions and variables most affected by LUC over North America.
Highlights
The climate and the general environment of our planet have been strongly modified by human activities [1,2] through time that are reflected in changes in emissions of trace gases into the atmosphere and land use change (LUC)
The above changes to leaf area index (LAI) leads to statistically significant differences in albedo between CRCM5_LUC and CRCM5_PV over these LUC regions, for the northern regions (Figure 3b), where albedo values are higher in CRCM5_LUC compared to CRCM5_PV
The regions south of 30 ̋ N show slightly higher values of albedo in CRCM5_LUC, despite the higher values of LAI, which is due to relatively drier soil layer at the surface in this simulation
Summary
The climate and the general environment of our planet have been strongly modified by human activities [1,2] through time that are reflected in changes in emissions of trace gases into the atmosphere and land use change (LUC). The most obvious manifestation of human activities is seen in the latter, in the form of deforestation or transformation of natural grassland into urban or cropland areas [3]. Climate can be influenced by LUC through biogeochemical and biophysical interactions. The biogeochemical effects alter the atmospheric gas composition of greenhouse gases, such as CO2 and CH4 ; this increase in the concentration of greenhouse gases can augment climate warming through a positive feedback [7,8,9]. The biophysical effects influence the surface energy budget by altering the Atmosphere 2016, 7, 34; doi:10.3390/atmos7030034 www.mdpi.com/journal/atmosphere
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