Comparison of CMIP5 and CMIP6 high-resolution simulations for soil
erosion response to climate and land use changes over China
Abstract
Soil erosion is impacted by climate and land use changes which need to
be quantified to assess future risks and to design efficient soil
conservation measures. The Coupled Model Intercomparison Project Phase 5
(CMIP5) simulations have provided the basis for most such assessments
and yet are being gradually superseded by more recent simulations from
Phase 6 (CMIP6). The High-Resolution Model Intercomparison Project
(HighResMIP) experiment in CMIP6 adds value over the downscaled CMIP5
simulations by improving process representation in the global climate
system. Our study investigates and compares high-resolution model
simulations from CMIP6 against CMIP5. Model evaluation for the reference
period (1986–2005) indicates that the CMIP6 model outperforms the
regional climate models (RCM) from CMIP5 for better circulation
simulations, but both overestimate soil erosion in China. The average
projected soil erosion increases by 27.85 from CMIP5 and 20.03
t·hm-2·a-1 from the CMIP6 model with remarkable geographical
heterogeneity. Soil erosion is projected to decrease in black soil
regions, purple soil regions, and karst regions from CMIP6 results,
which is opposite to the increasing trend found in those regions from
CMIP5. Land use and climatic changes contributed 51.68% and -5.92%
respectively from CMIP5 simulations while 35.74% and -13.77% from
CMIP6 to the increased soil erosion rate. The negative contribution of
land use change is gradually intensified with the CMIP6 model
representing finer-scale processes of converting land-use type into
cropland, pasture, and urban land. Overall, the CMIP6 projections
provide a less severe soil erosion situation while addressing the need
to pursue soil conservation more.