Global projections of flood risk under climate change

Floods are one of the most prevalent natural disasters globally, causing huge annual losses to the population and economies of the world. Identifying the distribution and evolution of global flood risk is essential in context of the growing trend of extreme natural hazards under climate change. This study presents predictions of global flood risk based on Global Climate Models (GCMs) under four Shared Socioeconomic Pathways (SSPs). Here our results demonstrate that a slow increase trend in global flood risk under different scenarios. Currently, about 23% of the global area is at very high risk of floods, which are concentrated in regions with high rainfall, flat terrain, and dense population and economic densities, such as eastern China, Japan and the eastern US. By the end of the 21st century (2081-2100), according to the SSP5-8.5 scenario, the global flood risk increases by up to about 2% overall compared to the baseline period (2001-2020), with an increase in the area at medium, high, and very high flood risk of about 780,316 km2. Over global countries with different income levels, high-income countries typically have a higher risk of floods than low-income countries, with 8 of the 10 most at-risk countries in the world being high-income countries. Singapore, Japan, Luxembourg, and South Korea are among the group of countries with the highest flood risk in the world. This study constructs a framework for global flood risk prediction from disaster-inducing factor, disaster-breeding environment, and disaster-bearing body, rather than just meteorological factors. These results indicate an increasing trend in global flood risk as predicted by a combination of factors, and we need to take mitigation measures to prevent the acceleration of these risks.