Future projection of land use change and its impacts on water resources and ecosystems investigated with MIROC-INTEG-LAND: a global bio-geophysical land surface model with human components

Abstract:

Future changes in the climate system could have significant impacts on the natural environment and human activities, which in turn affect changes in the climate system. In the interaction between natural and human systems under climate change conditions, land use is one of the elements that play an essential role. On the one hand, future climate change will affect the availability of water and food, which may impact land-use change. On the other hand, human-induced land-use change can affect the climate system through bio-geophysical and bio-geochemical effects. To investigate these interrelationships, we developed MIROC-INTEG-LAND (MIROC INTEGrated LAND surface model, Yokohata et al. 2020, https://gmd.copernicus.org/preprints/gmd-2019-184/gmd-2019-184.pdf), an integrated model that combines the land surface component of global climate model MIROC (Model for Interdisciplinary Research on Climate, Watanabe et al. 2010, Journal of Climate) with water resources (HiGWMAT, Pokhrel et al, 2012, Journal of Hydrometeorology), crop production (PRYSBI2, Sakurai et al, 2014, Scientific Reports), land ecosystem (VISIT, Ito and Inatomi 2012, Biogeosciences), and land use (Yokohata et al. 2020, Geosci. Model Dev.) models. The most significant feature of MIROC-INTEG-LAND is that the land surface model that describes the processes of the energy and water balance, human water management, and crop growth incorporates a land use decision-making model based on economic activities. In MIROC-INTEG-LAND, spatially detailed information regarding water resources and crop yields is reflected in the prediction of future land use change, which cannot be considered in the conventional integrated assessment models. In this study, we introduce the interconnections of the sub-models of MIROC-INTEG-LAND. By evaluating the historical simulation, we have confirmed that the model reproduces the observed states well. The future simulations indicate that changes in climate have significant impacts on crop yields, land use, and irrigation water demand. In the presentation, we will show the future changes in human land use and various impacts of land use change on natural ecosystem, water availability, and crop yields based on various socio-economic and climate scenarios.