Climate change problems: Rising sea levels

Global sea levels may rise by as much as 69cm during the next 100 years due to melting of glaciers and polar ice, and thermal expansion of warmer water.

Rising water levels will have serious impacts on marine ecosystems. The amount of light reaching offshore plants and algae dependent on photosynthesis could be reduced, while coastal habitats are already being flooded. Rapid sea level rise will likely be the greatest climate change challenge to mangrove ecosystems, which require stable sea levels for long-term survival. Marine turtles may also be affected as their nesting beaches become flooded.

Coastal cities and agricultural areas could also be flooded, with huge consequences: eight of the world’s ten largest cities are on coastal plains. Small island nations are likely to be severely affected - such as the Maldives in the Indian Ocean and Kiribati and Tuvalu in the Pacific Ocean, which are based entirely on coral atolls just a few metres above sea level. Salt water intrusion due to rising sea levels has already made groundwater undrinkable on some of these islands.

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