Photo Gallery How High Will Sea Levels Climb?
Waves on the coast of the Netherlands. Since the 1970s, the level of the North Sea has been rising. Countries bordering the body of water have responded by building ever higher dikes. Forecasts as to how quickly global sea levels are rising vary wildly.
Since 1880, sea levels on average have risen approximately 20 centimeters. Until 1993, data was gathered via coastal measurements. Since then, satellite data has been used. Researchers are debating whether the sea level rise has accelerated since then.
Satellite data on sea levels since 1993. Some researchers say that the rise in ocean levels has slowed down in the last eight years.
One of the problems in measuring sea levels is that the rise is not consistent everywhere. Some areas, as shown in this satellite image, rise faster than others. In some places, the level is even sinking.
A computer simulation of what a city on the Australian coast could look like in the future if sea levels continue to rise.
Current predictions as to how high sea levels might rise by the end of the century vary by up to five meters. Here, waves hitting the sea wall in Wales in 2008.
Venice, Italy is at particular risk of sea level rises. The city's central square has flooded increasingly often in recent decades.
In response, Venice is building a complex and expensive system of dikes to protect the old city center from flooding.
One of the decisive factors determining how quickly the world's ocean levels are rising is the rate at which glaciers are melting. That process, however, is not fully understood.
In particular, the ice sheets of Greenland, because of their size, are important for sea level rises. Here, an iceberg off the east coast of Greenland.
There are 150 million people living on land below one meter above sea level. The funding of efforts to protect them depend on scientific forecasts on how quickly sea levels are rising.
German Chancellor Angela Merkel visited Greenland in 2007 to raise awareness of global warming.
The melting of the Greenland ice sheet is accelerating. But the process remains poorly understood.
