Mangroves are intertidal communities of primarily tree species of the tropics and sub-tropics. Indonesia alone accounts for nearly a quarter of the world’s mangroves. These forests protect coasts against storms, tides, and cyclones. Mangroves are important in relation to animal and plant productivity, as nutrient sinks, for substrate stabilisation and as a source of wood products. Warming may promote expansion of mangroves to higher latitudes but they are susceptible to frost and drought. Many mangrove forests are excessively exploited, thereby reducing resilience in the face of sea-level rises. The importance of sediment flux in determining mangrove response to rising sea levels is well established in literature. It has been suggested that where there is low sediment supply mangrove accretion may not be able to keep pace with projected sea-level rises. In some protected coastal settings,the inundation of low-lying coastal land may promote the expansion of mangrove forests with rising sea levels provided vertical accretion keeps pace.

Studies have shown that mangrove forests in some areas will be lost as a result of elevated sea levels. For example, with a 1m sea level rise in Cuba, more than 300,000 hectares of mangroves, would be threatened. The same conditions could cause a complete collapse of the Port Royal mangrove wetland in Jamaica, which has shown little capacity to migrate in the past 300 years. Accelerated sea-level rises would adversely affect mangroves in Puerto Rico, where much has been destroyed already by man. The capacity of mangroves to adapt to sea-level rises by landward migration is now severely limited in many places by increasing human activities.

Some ecologists believe that mangrove communities are more likely to survive the effects of sea-level rise in macrotidal, sediment-rich environments where strong tidal currents redistribute sediment such as northern Australia, than in microtidal, sediment-starved environments like those in many small islands. As the rate of shoreline recession increases, mangrove stands are expected to become compressed and suffer a reduction in species diversity in the face of rising sea levels.

Mangroves need large amounts of fresh water for optimum growth, so they are more likely to be affected by a reduction in rainfall allowing greater saline intrusion than by higher temperatures and rising sea levels.