NASA
Sea Level Change
Skip Navigation
menu close modal
  • News & Features
    • Sea Level News
    • Scientist Interviews
    • News Briefs
  • Understanding Sea Level
    • Overview
    • Global Sea Level
    • Regional Sea Level
    • By the Numbers
    • Key Indicators
  • Science Team
    • Overview
    • Projects
    • Team Members
    • Presentations
  • Data
    • Data Search
    • Data Tools
    • Missions
  • Climate Tools
  • Resources
    • Multimedia
    • Publications
    • Glossary
  • FAQ
Stay Connected

Understanding Sea Level

  • Overview
  • Global Sea Level
  • Regional Sea Level
  • By the Numbers
  • Key Indicators
  • Overview
  • Short-term Effects
  • Sterodynamic
  • Glaciers
  • Land Water Storage
  • Ice Sheets
  • Subsidence

Regional Relative Sea-Level Change

Although changes in global mean sea level (GMSL) provide an important measure of the warming climate, when assessing potential impacts at the coast, it is the change in regional relative sea level that is most important. Regional relative sea-level change is influenced by multiple physical processes that vary both in space and time and can lead to large regional departures from the long-term rate of global mean sea-level rise. For each process, a brief description is provided, in addition to a summary of the observing systems used to measure that process, and a future outlook for the understanding of that process. While there are different ways to separate and group the contributing processes, we define regional relative sea-level change as follows, with each process changing in both space and time:


Regional Relative Sea Level = Short-Term Effects + Sterodynamic Variability + Glaciers + Land Water Storage + Ice Sheets + Subsidence


Short-term Effects: Variations of sea level on periods ranging from minutes to weeks that arise from processes like storm surge, wave runup, wave setup, astronomical tides and freshwater input.

Sterodynamic Variability: Sea level change that arises from variability in the ocean’s circulation, temperature and saltiness. This includes large-scale climate signals like the seasonal cycle, El Niño-Southern Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation. This also includes longer-term changes in ocean circulation that may occur in the future and global sea level rise associated with long-term warming of the ocean and associated expansion.

Glaciers: Glaciers outside of the ice sheets account for about 1% of total ice trapped on land. These changes are expressed regionally through gravitational, rotational and deformational (GRD) changes that have a characteristic pattern, or fingerprint.

Land Water Storage: Changes associated with the transfer of water between land and ocean. This includes variability in the global water cycle, groundwater withdrawal, and water impoundment. These changes are expressed regionally through gravitational, rotational and deformational (GRD) changes that have a characteristic pattern, or fingerprint.

Ice Sheets: The Greenland and Antarctic ice sheets contribute to global sea level rise, and these changes are expressed regionally through gravitational, rotational and deformational (GRD) changes that have a characteristic pattern, or fingerprint.

Subsidence: Movement of the land at the coast (could also be uplift) in response to a range of physical processes including groundwater and hydrocarbon withdrawal, tectonics, and glacial isostatic adjustment. These changes can vary widely in both time and space and can be associated with human activities.

Sea level trends (1993-2016) Regional sea-level change between 1992 and 2019, based on data collected from the TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellite altimeters. Blue regions are where sea level has gone down, and orange/red regions are where sea level has gone up. Since 1993, seas around the world have risen an average rate of 3.3 millimeters per year. Credit: NASA

  • Overview
  • Short-term Effects
  • Sterodynamic
  • Glaciers
  • Land Water Storage
  • Ice Sheets
  • Subsidence

Top Stories

Kelvin waves, a potential precursor of El Niño conditions in the ocean, are rolling across the equatorial Pacific toward the coast of South America.
More
International Sea Level Satellite Spots Early Signs of El Niño
International Sea Level Satellite Spots Early Signs of El Niño
Floating sea ice seems to have a small effect on sea level.
More
Melting Ocean Ice Affects Sea Level – Unlike Ice Cubes in a Glass
Melting Ocean Ice Affects Sea Level – Unlike Ice Cubes in a Glass
Sea level science team reveals complex, interlocking causes behind "nuisance" flooding events.
More
NASA Project Shows Hidden Factors Shape Minor Coastal Floods
NASA Project Shows Hidden Factors Shape Minor Coastal Floods
The first views from SWOT show the ocean, lakes and rivers in unprecedented detail.
More
Joint NASA, CNES Water-Tracking Satellite Reveals First Stunning Views
Joint NASA, CNES Water-Tracking Satellite Reveals First Stunning Views
Three decades of climate satellite observations helps researchers understand the drivers of sea level rise.
More
NASA Uses 30-Year Satellite Record to Track and Project Rising Seas
NASA Uses 30-Year Satellite Record to Track and Project Rising Seas
View and analyze projections of high-tide flooding frequency in coming decades for coastal locations around the U.S.
More
Flooding Analysis Tool
Flooding Analysis Tool

Newsletter

Stay Connected

News & Features

    • Sea Level News
    • Scientist Interviews
    • News Briefs

Understanding Sea Level

    • Overview
    • Global Sea Level
    • Regional Sea Level
    • By the Numbers
    • Key Indicators

Science Team

    • Overview
    • Projects
    • Team Members
    • Presentations

Data

    • Data Search
    • Data Tools
    • Missions

Climate Tools

    • Climate Tools

Resources

    • Multimedia
    • Publications
    • Glossary

FAQ

    • FAQ
  • Feedback
  • Privacy Policy

Site Manager: Carmen Blackwood
NASA Responsible Official: Stephen Berrick