Estimation of increase in storm surge damage due to climate change and sea level rise in the Greater Tokyo area

Sea level rise and an increase in typhoon intensity are two of the expected consequences from future climate change. In the present work, a methodology to change the intensity of tropical cyclones in Japan was developed, which can be used to assess the inundation risk to different areas of the country. As a result, the probability of a storm with an equivalent return period in the year 2100 to that of the worst storm in the 20th century overcoming sea defences around Tokyo Bay could be calculated. The risk of higher storm surges, coupled with different sea-level-rise scenarios, highlights how the dykes around Tokyo or Kawasaki could fail unless adaptation measures against climate change are attempted. The cost of adapting to both of these effects by building higher coastal dykes and raising port areas outside them was quantified. Finally, an estimation of the cost of allowing the areas behind the defences to be flooded was also made, clearly showing that the cost of adaptation measures is clearly lower than the cost of inaction.