think climate. think change.
Global average sea level rose by approximately 17 cm (the range was 12-22 cm) during the 20th century. It is very likely that increasing temperatures in the 20th century contributed to this sea level rise through thermal expansion of seawater and widespread loss of land ice (retreating glaciers).
The IPCC Fourth Assessment Report says that sea level is likely to rise by an additional 18 to 59 cm by the year 2100, but this does not include possible changes in big ice sheets such as Greenland and the Antarctic that could lead to more rapid sea level rise. This rise may affect low-lying islands and coastal settlements throughout the world.
As the Earth's surface warms, the oceans slowly absorb heat and expand, causing the sea level to rise. This thermal expansion of the ocean will be a major contributor to sea level rise during future centuries.
Melting of glaciers is also expected to contribute to rising sea levels. Melting ice from Greenland is expected to make a small contribution to rising sea levels this century, offset in part by increased snow on the Antarctic ice sheet. Very little melting is expected to occur over the Antarctic mainland during the next century because of the very long response time to atmospheric warming and the low temperatures there.
Based on a range of possible future scenarios for global warming, scientists estimate that sea levels will rise between 18 and 59 cm by the year 2100 as oceans expand and glaciers melt.
This graph is based on information from the Intergovernmental Panel on Climate Change Fourth Assessment Report 2007.
The original graphs can be accessed at: www.ipcc.ch/
