Quantifying Land and People Exposed to Sea‐Level Rise with No Mitigation and 1.5°C and 2.0°C Rise in Global Temperatures to Year 2300.

Abstract: We use multiple synthetic mitigation sea‐level scenarios, together with a non‐mitigation sea‐level scenario from the Warming Acidification and Sea‐level Projector model. We find sea‐level rise (SLR) continues to accelerate post‐2100 for all but the most aggressive mitigation scenarios indicative of 1.5°C and 2.0°C. Using the Dynamic Interactive Vulnerability Assessment modeling framework, we project land and population exposed in the 1 in 100 year coastal flood plain under SLR and population change. In 2000, the flood plain is estimated at 540 × 10³ km². By 2100, under the mitigation scenarios, it ranges between 610 × 10³ and 640 × 10³ km² (580 × 10³ and 700 × 10³ km² for the 5th and 95th percentiles). Thus differences between the mitigation scenarios are small in 2100. However, in 2300, flood plains are projected to increase to between 700 × 10³ and 960 × 10³ km² in 2300 (610 × 10³ and 1290 × 10³ km²) for the mitigation scenarios, but 1630 × 10³ km² (1190 × 10³ and 2220 × 10³ km²) for the non‐mitigation scenario. The proportion of global population exposed to SLR in 2300 is projected to be between 1.5% and 5.4% (1.2%–7.6%) (assuming no population growth after 2100) for the aggressive mitigation and the non‐mitigation scenario, respectively. Hence over centennial timescales there are significant benefits to climate change mitigation and temperature stabilization. However, sea‐levels will continue to rise albeit at lower rates. Thus potential impacts will keep increasing necessitating adaptation to existing coastal infrastructure and the careful planning of new coastal developments. [ABSTRACT FROM AUTHOR]