Sea level rise can be defined as an increase in sea level caused by global warming through two main processes: the thermal expansion of sea water and the rapid melting of land ice.

Sea level rise is also expected to make coastal cities more vulnerable to extreme weather (such as hurricanes) as well as to destroy important ecosystems such as wetlands and mangroves. Rising sea level inundates low-lying lands, erodes shorelines, exacerbates flooding, and increases the salinity of estuaries and aquifers. Islands are particularly exposed as many are gradually facing the loss of their fresh water supply due to salt-water intrusion. Low-lying coastal areas and deltas (the land where rivers feed into the ocean) house at least 300 million people and are particularly threatened by sea level rise.
Some developing countries are especially exposed to sea level rise due to their low- lying nature and limited financial resources to respond. Among the most vulnerable are countries with large populations in deltaic coastal regions such as Bangladesh, Vietnam, China and Egypt.