Sea level rise is the gradual increase in ocean water over time, which can be influenced by local conditions as well as global trends. It is caused by melting glaciers and ice sheets, thermal expansion of seawater as it warms, and sinking land. It is expected to accelerate as climate change progresses and greenhouse gas emissions continue to increase.
Rising sea levels threaten coastal communities worldwide by increasing the frequency and severity of flood events. This includes not only storm surges but also high tides, river flows, and heavy rains. It can damage and disrupt infrastructure, such as roads, subways, drinking water supply systems, power plants, oil and gas pipelines, sewage treatment facilities, and fishing harbors. It can contaminate freshwater supplies and destroy marine life habitats. It can also lead to increased tidal erosion and the destruction of historic buildings.
Tens of millions of people in the US and hundreds of million globally live in areas that are at risk from coastal flooding. Sea level rise and eroding coastlines will combine with other factors like high storm surges to cause more frequent, severe coastal flooding.
In addition to physical dangers from flooding and displacement, sea level rise can also threaten human health by contaminating drinking water supplies with salt, creating conditions for disease-causing mold growth, and limiting access to health care services. It can also affect economic development as people relocate to safer areas or businesses move inland. Societies can adapt to sea level rise through “hard” strategies such as managed retreat and dune rehabilitation, or through “soft” approaches such as coastal planning and adaptive management.