Title: Climate Change Indicators: Sea Level | Climate Change Indicators in the United States | US EPA
Headings: Climate Change Indicators: Sea Level
Climate Change Indicators
Climate Change Indicators: Sea Level
Key Points
Background
About the Indicator
About the Data
Indicator Notes
Data Sources
Technical Documentation
References
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Content: Higher sea level also makes coastal infrastructure more vulnerable to damage from storms. The sea level changes that affect coastal systems involve more than just expanding oceans, however, because the Earth’s continents can also rise and fall relative to the oceans. Land can rise through processes such as sediment accumulation (the process that built the Mississippi River delta) and geological uplift (for example, as glaciers melt and the land below is no longer weighed down by heavy ice). In other areas, land can sink because of erosion, sediment compaction, natural subsidence (sinking due to geologic changes), groundwater withdrawal, or engineering projects that prevent rivers from naturally depositing sediments along their banks. Changes in ocean currents such as the Gulf Stream can also affect sea levels by pushing more water against some coastlines and pulling it away from others, raising or lowering sea levels accordingly. Scientists account for these types of changes by measuring sea level change in two different ways. Relative sea level change refers to how the height of the ocean rises or falls relative to the land at a particular location. In contrast, absolute sea level change refers to the height of the ocean surface above the center of the earth, without regard to whether nearby land is rising or falling. About the Indicator
This indicator presents trends in sea level based on measurements from tide gauges and from satellites that orbit the Earth. Tide gauges measure relative sea level change at points along the coast, while satellite instruments measure absolute sea level change over nearly the entire ocean surface.