Mangroves and their services are at risk from climate-modified tropical cyclones and sea level rise

Climate change is expected to alter the frequency and intensity of extreme events, modifying the natural disturbance regimes to which ecosystems are currently adapted. Here, we present a spatially explicit risk index for mangroves and their associated biodiversity and ecosystem services based on projected frequency changes of tropical cyclone wind speeds and rates of relative sea level rise under SSPs 245, 370 and 585 by 2100.

To compute the risk index, we calculate the relative change of tropical cyclone frequency across different wind speed intensity categories based on probabilistic tropical cyclone tracks downscaled from 3 different CMIP6 models of varying climate sensitivity. This data is then combined with thresholds of sea level rise which are estimated to exceed mangrove adaptive capacity and mapped onto global mangrove extents.

Globally, approximately half of the total mangrove area (40-56% depending on the SSP) will be at high to severe levels of risk due to climate-modified tropical cyclone disturbance regimes. Further, we find mangrove areas with high levels of biodiversity and ecosystem services provision, including coastal protection for people and assets, carbon sequestration, and fishery benefits, are at proportionally higher levels of risk than mangrove forests generally. We also identify mangrove areas which are projected to experience non-analog tropical cyclone disturbances in the future. Our findings emphasize the need to anticipate changes in natural disturbance regimes to adapt ecosystem management, sustain ecosystem services in the future, and fully realize mangroves’ potential as nature-based solutions (NBS).