Comparison between impacts of global climate change and urbanization on local climate in Tokyo metropolitan area, Japan

Tokyo metropolitan area is a most densely populated area. If the global surface temperature continues to increase in the future as well as the regional urbanization, the heat stress of the residents seems to be magnified, especially summer season. This study tried the quantitative estimation of the impacts of the global climate change and the land-use change on the local climate change by the dynamical downscaling. The pseudo climate change method was applied to the boundary conditions. At first, some numerical simulations were carried out and reproduced the past climate change to validate the method. And then, the method was applied to future climate and estimated both impacts. The future climate data was given by selected five CGCM projections assuming IPCC SRES-A1B scenario. The intensities of the warming at the surface level were individually estimated for the increase of the greenhouse gases and for the change in land-use. Results show that the uncertainty in the temperature projection caused by bias of the GCMs is very large and the range of uncertainty is larger than the estimated temperature increase caused by future change in land-use.