If nothing’s done to adapt to and mitigate climate change, Tokyo would face severe costs if a one-in-100-year rainfall coincides with other major flooding events—raising the stakes from around $6 billion in damage to real estate and infrastructure today to about $13 billion in 2050.
Flooding in Tokyo is expected to become more frequent and intense by 2050 due to climate change in the absence of adaptation and mitigation.
| Date | Flooded area within modeled area1 | Average flooded depth within modeled areas | Real estate damage and destruction | Infrastructure damage and destruction2 |
|---|---|---|---|---|
| Today | 64% | 0.3 meters | $5.9 billion | $0.4 billion |
| 2050 | 81% | 0.5 meters (increase of 1.7×) | $13.1 billion (increase of 2.2×) | $1.1 billion (increase of 2.4×) |
Notes
See Technical appendix, Climate risk and response: Physical hazards and socioeconomic impacts, McKinsey Global Institute, January 2020, for why we chose RCP 8.5. Following standard practice, climate state today is defined as average conditions between 1998 and 2017, in 2030 as average between 2021 and 2040, and in 2050 as average between 2041 and 2060. To simulate the worst-case scenario, all three flood sources were used as inputs to model the 24-hour compound flood event. In this context the compound flood event is defined as the flood extent caused by the 1-in-100-year flood rainfall, streamflow, and storm surge events occurring simultaneously. The 1-in-100-year flood rainfall, streamflow, and storm surge values were calculated independently from each other using various data sources. These events are not independent, and this was done therefore in order to avoid underestimating flood risk and to provide a realistic estimate of the 1-in-100-year flood event. See Technical appendix for further details.
1Flooded area considered for grids with depth greater than 0.01.
2Damage identified for several assets (eg, substations, stations, data centers, hospitals).
Source: European Commission; Woodwell Climate Research Center; McKinsey Global Institute analysis
McKinsey & Company
To read the article, see “Climate risk and response in Asia,” November 24, 2020.