A GIS-Based Approach to Adaptation to Regional Climate Change for Local Decision-Making Arrangements: A Case Study of Tokyo, Japan

Abstract

"Recently, local governments have an increasing need to take extensive and effective local measures to adapt to regional climate change. Despite emerging recognition of the necessity of climate change adaptation, many barriers still impede efforts to build local, regional, and national-level resilience. This study aims: 1) to develop a Geographic Information System (GIS) based approach to using observed and projected data for decision-making by non-expert government authorities, 2) to explore the value of regional priorities in climate change adaptation planning processes using GIS, and 3) to provide specialized yet understandable climate change projection to local decision-makers efficiently and equally by GIS, who are invoking the concept of resilience as a management goal. Tokyo, Japan (a megacity with a population of 13.23 million as of 1 April 2013), was chosen for this pilot study. In this paper, the most recent regional climate projections (5 km resolution) are transcribed into an understandable form. Moreover, a general approach has been developed to adjust the bias of model results using observations. The mean temperature increase at Okutama-machi, a sparsely populated mountainous region (area 225.63 km2) to the northwest of the city of Tokyo, with the highest peak (2,017 m), is the greatest of any area in Tokyo. In comparing near future time period (2015-2039) and future time period (2075-2099) conditions, August monthly mean temperature will increase more than 0.7-0.9 °C and 2.6-2.9 °C, and monthly precipitation by 43-70 % and 25-41 %, respectively. Additionally, the RMS errors and bias of percentage change for monthly precipitation in summertime are 26.8 % and 4.3 %, respectively. These data provide an early warning and have implications for local climate policy response."