Know Your Earth 2.0: Sea Level Rise
Three factors contribute to global sea level rise: 1) Thermal expansion of seawater due to global warming; 2) Widespread melting of land ice; and 3) Loss of mass from the Greenland and Antarctic ice sheets.
Since 1992, altimeters aboard NASA and partner spacecraft have made scientific measurements showing that global sea level is on the rise, threatening coastal communities around the world. The Jason-1 and OSTM/Jason-2 satellite altimeters make precise measurements of sea level height but show a complicated pattern of rising and falling seas across the globe.
Predicting future sea level rise remains extremely difficult. Sea level projections from the 2001 IPCC assessment report significantly underestimated the rate of sea level rise over the past two decades. On the other hand, the 2007 IPCC report placed no upper bound on sea level rise projections for the 21st century. Much of this uncertainty comes from a lack of knowledge about how glaciers and ice sheets will respond to a warming climate. NASA research indicates
that El Niño and La Niña conditions can also have a significant impact on sea levels and add to the uncertainty of predicting future global and local sea level rise. Such uncertainty underscores the need to continue the precise measurements of global sea level made by satellite altimeters such as Jason-1 and OSTM/Jason-2.