Sea level

2023-03-22

Table of contents

Climate change indicators: Sea level
Key points
Background
About the indicator
About the Data
- Indicator Notes
- Data Sources

Climate change indicators: Sea level

This indicator describes changes in sea level over time. The hand describes two types of sea level change: absolute and relative.

Figure 1. Global Average Absolute Sea Level Change, 1880–2021

Global Average Absolute Sea Level Change, 1880–2021

This graph shows cumulative sea level changes for the world’s oceans since 1880, based on long-term tide gauge measurements and recent satellite measurements. This figure shows the mean absolute change in sea level, which refers to the height of the ocean surface, whether nearby land is rising or falling.

Satellite data is based only on measured sea level, while long-term tide gauge data includes a small correction factor as the size and shape of the oceans change slowly over time. The shaded band shows the likely range of values, depending on the number of measurements collected and the methods’ precision.

Year	CSIRO – Adjusted sea level (inches)	CSIRO – Lower error bound (inches)	CSIRO – Upper error bound (inches)	NOAA – Adjusted sea level (inches)
1880	0	-0.95276	0.952756
1881	0.220472	-0.73228	1.173228
1882	-0.44094	-1.34646	0.464567
1883	-0.23228	-1.12992	0.665354
1884	0.590551	-0.28346	1.464567
1885	0.531496	-0.33071	1.393701
1886	0.437008	-0.38189	1.255906
1887	0.216535	-0.60236	1.035433
1888	0.299213	-0.51969	1.11811
1889	0.362205	-0.45669	1.181102
1890	0.440945	-0.37402	1.255906
1891	0.374016	-0.44094	1.188976
1892	0.5	-0.31496	1.314961
1893	0.685039	-0.11417	1.484252
1894	0.30315	-0.54724	1.153543
1895	0.767717	-0.08268	1.61811
1896	0.468504	-0.36614	1.30315
1897	0.673228	-0.14567	1.492126
1898	1.043307	0.267717	1.818898
1899	1.338583	0.574803	2.102362
1900	1.125984	0.405512	1.846457
1901	1.110236	0.417323	1.80315
1902	1.291339	0.610236	1.972441
1903	1.606299	0.937008	2.275591
1904	1.200787	0.535433	1.866142
1905	0.984252	0.377953	1.590551
1906	1.251969	0.673228	1.830709
1907	1.19685	0.610236	1.783465
1908	1.098425	0.527559	1.669291
1909	1.275591	0.700787	1.850394
1910	1.271654	0.69685	1.846457
1911	1.598425	1.03937	2.15748
1912	1.476378	0.917323	2.035433
1913	1.547244	0.992126	2.102362
1914	1.795276	1.251969	2.338583
1915	2.106299	1.570866	2.641732
1916	2.031496	1.519685	2.543307
1917	1.854331	1.350394	2.358268
1918	1.791339	1.291339	2.291339
1919	1.854331	1.354331	2.354331
1920	1.905512	1.393701	2.417323
1921	1.988189	1.472441	2.503937
1922	1.952756	1.433071	2.472441
1923	2	1.488189	2.511811
1924	1.712598	1.19685	2.228346
1925	1.791339	1.255906	2.326772
1926	2.047244	1.507874	2.586614
1927	2.003937	1.496063	2.511811
1928	1.850394	1.366142	2.334646
1929	1.905512	1.429134	2.38189
1930	2.062992	1.590551	2.535433
1931	2.047244	1.566929	2.527559
1932	2.271654	1.80315	2.740157
1933	2.440945	1.976378	2.905512
1934	2.228346	1.759843	2.69685
1935	2.448819	1.980315	2.917323
1936	2.295276	1.830709	2.759843
1937	2.519685	2.055118	2.984252
1938	2.622047	2.15748	3.086614
1939	2.826772	2.346457	3.307087
1940	2.61811	2.181102	3.055118
1941	3.098425	2.673228	3.523622
1942	3.098425	2.673228	3.523622
1943	3.098425	2.673228	3.523622
1944	2.846457	2.425197	3.267717
1945	2.956693	2.535433	3.377953
1946	3.251969	2.834646	3.669291
1947	3.374016	2.996063	3.751969
1948	3.562992	3.19685	3.929134
1949	3.511811	3.181102	3.84252
1950	3.598425	3.287402	3.909449
1951	3.972441	3.665354	4.279528
1952	3.870079	3.566929	4.173228
1953	4.043307	3.748031	4.338583
1954	3.929134	3.641732	4.216535
1955	3.964567	3.685039	4.244094
1956	3.76378	3.488189	4.03937
1957	4.291339	4.019685	4.562992
1958	4.346457	4.086614	4.606299
1959	4.358268	4.102362	4.614173
1960	4.503937	4.244094	4.76378
1961	4.748031	4.488189	5.007874
1962	4.543307	4.283465	4.80315
1963	4.480315	4.220472	4.740157
1964	4.169291	3.905512	4.433071
1965	4.610236	4.346457	4.874016
1966	4.397638	4.137795	4.65748
1967	4.452756	4.19685	4.708661
1968	4.484252	4.220472	4.748031
1969	4.751968	4.476378	5.027559
1970	4.677165	4.401575	4.952756
1971	4.88189	4.610236	5.153543
1972	5.240157	4.968504	5.511811
1973	5.003937	4.73622	5.271654
1974	5.472441	5.204724	5.740157
1975	5.409449	5.145669	5.673228
1976	5.370079	5.102362	5.637795
1977	5.30315	5.043307	5.562992
1978	5.555118	5.291339	5.818898
1979	5.362205	5.098425	5.625984
1980	5.598425	5.34252	5.854331
1981	6.086614	5.830709	6.34252
1982	5.858268	5.610236	6.106299
1983	6.188976	5.933071	6.444882
1984	6.153543	5.905512	6.401575
1985	5.748031	5.5	5.996063
1986	5.771654	5.523622	6.019685
1987	5.795276	5.551181	6.03937
1988	5.980315	5.732283	6.228346
1989	6.15748	5.905512	6.409449
1990	6.248031	5.992126	6.503937
1991	6.346457	6.090551	6.602362
1992	6.374016	6.114173	6.633858
1993	6.30315	6.043307	6.562992	6.306781
1994	6.507874	6.248031	6.767717	6.438652
1995	6.622047	6.362205	6.88189	6.576745
1996	6.783465	6.523622	7.043307	6.72371
1997	7.059055	6.799213	7.318898	6.779515
1998	6.669291	6.401575	6.937008	6.770265
1999	7.003937	6.73622	7.271654	6.840497
2000	7.055118	6.787402	7.322835	6.919122
2001	7.271654	7.007874	7.535433	7.116326
2002	7.366142	7.098425	7.633858	7.258224
2003	7.728346	7.456693	8	7.410512
2004	7.712598	7.440945	7.984252	7.465565
2005	7.716535	7.448819	7.984252	7.566646
2006	7.885827	7.61811	8.153543	7.678405
2007	7.96063	7.681102	8.240157	7.674413
2008	8.30315	8.035433	8.570866	7.828384
2009	8.531496	8.259843	8.80315	7.973213
2010	8.834646	8.555118	9.114173	8.030874
2011	8.897638	8.602362	9.192913	7.966928
2012	9.244094	8.917323	9.570866	8.36211
2013	8.913386	8.562992	9.26378	8.453538
2014				8.579036
2015				8.924984
2016				9.048399
2017				9.110986
2018				9.234521
2019				9.480223
2020				9.592477
2021				9.79722

Figure 1. Global Average Absolute Sea Level Change, 1880-2021
Data source: CSIRO, 2017; NOAA, 2022
Web update: July 2022
Units: inches

Figure 2. Relative Sea Level Change Along U.S. Coasts, 1960–2021

This map shows cumulative changes in relative sea level from 1960 to 2021 at tide stations along US coasts. Relative sea level reflects changes in sea level as well as land elevation.

Lat	Long	Station Name	State	Relative sea-level change
21.955	-159.357	Nawiliwili	Hawaii	4.250787
21.307	-157.867	Honolulu	Hawaii	3.722441
21.437	-157.793	Mokuoloe	Hawaii	4.058661
20.898	-156.472	Kahului	Hawaii	5.427559
19.73	-155.057	Hilo	Hawaii	7.564961
28.212	-177.36	Midway Atoll	Pacific Ocean	3.554331
8.737	167.738	Kwajalein	Marshall Islands	4.875197
19.29	166.618	Wake Island	Pacific Ocean	5.187402
32.373	-64.703	Bermuda	Atlantic Ocean	5.211417
44.903	-66.985	Eastport	Maine	5.30748
44.392	-68.205	Bar Harbor	Maine	5.523622
43.657	-70.247	Portland	Maine	4.562992
42.355	-71.052	Boston	Massachusetts	6.940551
41.523	-70.672	Woods Hole	Massachusetts	7.156693
41.505	-71.327	Newport	Rhode Island	6.844488
41.807	-71.402	Providence	Rhode Island	5.835827
41.355	-72.087	New London	Connecticut	6.628346
41.048	-71.96	Montauk	New York	8.261417
40.81	-73.765	Kings Point	New York	5.595669
40.7	-74.015	The Battery	New York	6.940551
40.467	-74.01	Sandy Hook	New Jersey	10.01457
39.355	-74.418	Atlantic City	New Jersey	9.990551
39.933	-75.142	Philadelphia	Pennsylvania	7.348819
39.558	-75.573	Reedy Point	Delaware	9.029921
38.782	-75.12	Lewes	Delaware	8.669685
38.573	-76.068	Cambridge	Maryland	9.342126
39.267	-76.578	Baltimore	Maryland	7.781102
38.983	-76.48	Annapolis	Maryland	8.957874
38.317	-76.452	Solomons Island	Maryland	9.510236
38.873	-77.022	Washington	D. C.	8.261417
37.167	-75.988	Kiptopeke	Virginia	9.246063
36.947	-76.33	Sewells Point	Virginia	11.38346
34.72	-76.67	Beaufort	North Carolina	8.069291
34.227	-77.953	Wilmington	North Carolina	6.26811
33.655	-78.918	Springmaid Pier	South Carolina	9.678346
32.782	-79.925	Charleston	South Carolina	8.141339
32.033	-80.902	Fort Pulaski	Georgia	8.261417
30.672	-81.465	Fernandina Beach	Florida	5.283465
30.397	-81.43	Mayport	Florida	6.676378
24.553	-81.808	Key West	Florida	6.051968
27.76	-82.627	St. Petersburg	Florida	7.132677
29.135	-83.032	Cedar Key	Florida	5.451575
30.403	-87.212	Pensacola	Florida	6.220079
29.263	-89.957	Grand Isle	Louisiana	22.04646
29.73	-93.87	Sabine Pass	Texas	14.7937
29.31	-94.793	Galveston Pier 21	Texas	15.89843
28.022	-97.047	Rockport	Texas	14.26535
26.06	-97.215	Port Isabel	Texas	10.20669
32.713	-117.173	San Diego	California	5.283465
32.867	-117.258	La Jolla	California	4.899213
33.72	-118.272	Los Angeles	California	2.497638
34.008	-118.5	Santa Monica	California	3.674409
35.177	-120.76	Port San Luis	California	2.329528
37.807	-122.465	San Francisco	California	4.731102
37.772	-122.298	Alameda	California	2.08937
41.745	-124.183	Crescent City	California	-1.92126
46.208	-123.767	Astoria	Oregon	-0.38425
48.368	-124.617	Neah Bay	Washington	-4.17874
47.605	-122.338	Seattle	Washington	4.97126
48.547	-123.01	Friday Harbor	Washington	2.857874
55.333	-131.625	Ketchikan	Alaska	-0.9126
57.052	-135.342	Sitka	Alaska	-5.93189
58.298	-134.412	Juneau	Alaska	-32.1331
59.45	-135.327	Skagway	Alaska	-43.2283
51.863	-176.632	Adak Island	Alaska	-6.05197
53.88	-166.537	Unalaska	Alaska	-10.9031
17.972	-67.047	Magueyes Island	Puerto Rico	4.635039

Figure 2. Relative Sea Level Change Along U.S. Coasts, 1960-2021
Data source: NOAA, 2022
Web update: July 2022
Units: inches

Key points

After about 2,000 years of little change, the global mean sea level rose throughout the 20th century, and the rate of change has accelerated in recent years.

Overall oceans Worldwide, the absolute sea level averaged 0.06 inches per year from 1880 to 2013 (see Figure 1).

Since 1993, however, the mean sea level has risen at a rate of 0.12 to 0.14 inches per year, about twice as fast as the long-term trend.
Relative sea level has risen along much of the U.S. coastline between 1960 and 2021, particularly the Mid-Atlantic Coast and parts of the Gulf Coast, where some stations have recorded increases of more than 8 inches (see Figure 2).

Meanwhile, relative sea levels have fallen in Alaska and the Pacific Northwest. Although the absolute sea level has risen at these sites, land elevation has increased more rapidly.
Although the absolute sea level has risen steadily, particularly in recent decades, regional trends vary.

The fundamental sea level has fallen in some places due to changes in coastal circulation patterns.
As the Earth’s temperature changes, the sea level also changes.

Background

As the Earth’s temperature changes, so do the sea level.

Changes in the amount of water and ice on land can increase or decrease the amount of water in the ocean.

As the water warms, it expands slightly—an effect cumulative across the entire ocean depth.

Changing sea levels can affect human activities in coastal areas. Rising sea levels inundate low-lying wetlands and dry land, erode coastlines, contribute to coastal flooding, and increase saltwater flow into estuaries and nearby aquifers.

Higher sea levels also make coastal infrastructure more vulnerable to storm damage.

However, sea level changes affecting coastal systems are not only related to the expansion of the oceans because the Earth’s continents can also rise and fall relative to the oceans.

Soil can increase through processes such as sediment accumulation and geological uplift. In other areas, soils may subside due to erosion, sediment compaction, natural subsidence, groundwater withdrawal, or engineering projects that naturally prevent rivers from depositing sediment along their banks.

Changes in ocean currents, such as Gulf Stream, can also affect sea levels by pushing more water onto some coasts and pulling moisture away from others, raising or lowering sea levels respectively.

Scientists explain these changes by measuring sea level change in two different ways. Relative sea level change refers to an increase or decrease in the height of the ocean close to land at a particular location.

In contrast, absolute sea level change refers to the elevation of the ocean’s surface above the center of the earth, regardless of whether nearby land rises or falls.

Evidence shows that sea levels along the US coast will increase by 10 to 12 inches by 2050—the same increase measured from 1920 to 2020.

About the indicator

This indicator presents sea level trends based on measurements from tide gauges and satellites orbiting the Earth. Tide gauges measure the relative change in sea level at points along the coast.

In contrast, satellite instruments measure the absolute difference in sea level over almost the entire ocean surface. Many tide gauges have been collecting data for over 100 years, while satellites have been collecting data since the early 1990s.

Figure 1 shows the absolute annual sea level change averaged over the entire surface of the Earth’s ocean. The long-term trend is based on tide gauge data that has been adjusted to show absolute global trends through calibration with recent satellite data.

This long-term dataset was calculated through 2013, while satellite data is now available through the end of 2021. Atlantic, Pacific, and Gulf Coasts of the United States.

About the Data

Indicator Notes

Relative sea level trends represent absolute sea level change and local land motion. Tidal measurements such as those in Figure 2 generally cannot distinguish between these two influences without accurately measuring nearby vertical land motion.

Some relative and absolute sea-level changes may be due to multi-year cycles such as El Niño and La Niña, which affect coastal ocean temperatures, salt content, wind patterns, atmospheric pressure, and currents.

Obtaining a reliable trend can require many years of data, so the satellite record in Figure 1 has been supplemented with a longer-term reconstruction based on tide gauge measurements.

Data Sources

Australia’s Commonwealth Scientific and Industrial Research Organization and the National Oceanic and Atmospheric Administration provided absolute sea level trends. These data are based on measurements collected by satellites and tide gauges.

Relative sea level data is available from the National Oceanic and Atmospheric Administration, which publishes an interactive map online with links to detailed data for each tide gauge.