[20160912]IF10468_海平面上升与美国海岸.pdf

https:/crsreports.congress.gov September 12, 2016Sea-Level Rise and U.S. CoastsPolicymakers are interested in sea-level rise because of the risk to U.S. coastal populations and infrastructure and changes to coastal ecosystems. Some coastal states and U.S. territories have a considerable share of their assets, people, economies, and water supplies vulnerable to sea-level rise. Policy choices related to sea-level rise have the potential to shape the future development and resiliency of U.S. coasts. What Is Sea-Level Rise? Scientists commonly use two descriptions of sea level: global sea level (GSL) and relative sea level (RSL). GSL is the average height of the Earths oceans. RSL refers to the elevation of the sea level relative to the land surface from which it is measured. From 1901 to 2010, GSL rose an estimated 187 millimeters (mm), or 7.4 inches, averaging a 1.7 mm (0.07 inches) rise annually, according to several studies using tide gage data. Satellite measurements, available since 1992, indicate an increase in the annual rate of GSL rise to 3.2 mm (0.13 inches) through 2010. The drivers for rising GSL since 1900 are predominantly thermal expansion of the oceans due to warming