Sea level | Rising Tide, Climate Change & Global Warming

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Here's what's being done about it</a> <span class="font-14 text-gray-600"> <span>•</span> Nov. 26, 2024, 1:27 PM ET (AP) </span> </div> </div> <div class="rest-of-recent-news-items"> <button class="js-toggle-recent-news d-flex btn btn-unstyled font-14 pr-10 rounded-sm mt-10" aria-label="Toggle additional news items"> Show less <em class="material-icons" data-icon="expand_less"></em> </button> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><div class="assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100" data-type="other"><div class="slider-container js-slider-container overflow-hidden d-flex"><div class="rw-track d-flex align-items-center"><div class="position-relative rw-slide col-100 px-20 "><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="193678" data-asm-type="video"><div class="md-assembly-wrapper card-media " data-type="video" video-id="179993"><a data-id="179993" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/sea-level/-193678"><img src="https://cdn.britannica.com/93/179993-138-117F7459/sea-level.jpg?w=800&h=450&c=crop" alt="How do satellites help measure sea levels?" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/Yf8D4bq1.m3u8" } ], "image": "https://cdn.britannica.com/93/179993-138-117F7459/sea-level.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/6C0BmcFY", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/wpYAtNrn.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="179993">How do satellites help measure sea levels?</span><span>Learn how sea level is measured.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/science/sea-level/images-videos">See all videos for this article</a></figcaption></figure></div></div></div><button disabled="true" class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_left"></span></button><button disabled="true" class="next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_right"></span></button></div><p class="topic-paragraph"><strong><span id="ref119307"></span>sea level</strong>, position of the <a href="https://www.britannica.com/science/air-sea-interface" class="md-crosslink autoxref " data-show-preview="true">air-sea interface</a>, to which all <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="terrestrial" href="https://www.britannica.com/dictionary/terrestrial" data-type="EB">terrestrial</a> elevations and submarine depths are referred. The sea level constantly changes at every locality with the changes in tides, <a href="https://www.britannica.com/science/atmospheric-pressure" class="md-crosslink autoxref " data-show-preview="true">atmospheric pressure</a>, and wind conditions. Longer-term changes in sea level are influenced by <a href="https://www.britannica.com/place/Earth" class="md-crosslink autoxref " data-show-preview="true">Earth’s</a> changing climates. Consequently, the level is better defined as <span id="ref119308"></span><a href="https://www.britannica.com/science/mean-sea-level" class="md-crosslink ">mean sea level</a>, the height of the sea surface averaged over all stages of the <a href="https://www.britannica.com/science/tide" class="md-crosslink autoxref " data-show-preview="true">tide</a> over a long period of time.</p><div class="one-good-fact-module"> </div><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="157628" data-asm-type="image"><div class="md-assembly-wrapper card-media " data-type="image"><a href="https://cdn.britannica.com/39/129739-050-AF5A80E5/Change-sea-surface-height-data-satellites-Jason-1-2008.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/530603/157628"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/39/129739-050-AF5A80E5/Change-sea-surface-height-data-satellites-Jason-1-2008.jpg?w=300"><img src="https://cdn.britannica.com/39/129739-050-AF5A80E5/Change-sea-surface-height-data-satellites-Jason-1-2008.jpg?w=300" alt="global sea surface height change, 1993–2008" data-width="851" data-height="604" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/39/129739-050-AF5A80E5/Change-sea-surface-height-data-satellites-Jason-1-2008.jpg" data-href="/media/1/530603/157628">global sea surface height change, 1993–2008</a><span>Change in sea surface height from 1993 to 2008, using data collected from the Topex/Poseidon and Jason-1 satellites.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">Global mean sea level rose at an average rate of about 1.2 mm (0.05 inch) per year over much of the 20th century, with shorter terms during which the rise was significantly faster (5.5 mm [0.2 inches] per year during the period from 1946 to 1956). This variable rise has been shown to have occurred for a very long time. The sea level appears to have been very close to its present position 35,000 years ago. It dropped 130 metres (426 feet) or more during the interval from 30,000 to 15,000 years ago and has been rising ever since. Fluctuations of equivalent magnitude probably have accompanied the <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="alternate" href="https://www.britannica.com/dictionary/alternate" data-type="EB">alternate</a> growth and melting of continental glaciers during the <a href="https://www.britannica.com/science/Pleistocene-Epoch" class="md-crosslink " data-show-preview="true">Pleistocene Epoch</a> (from 2.6 million to 11,700 years ago) because the <a href="https://www.britannica.com/science/ocean" class="md-crosslink autoxref " data-show-preview="true">ocean’s</a> waters are the ultimate source of glacial ice. Slower changes in the shapes and sizes of the ocean basins have less effect.</p><span class="marker MOD2 mod-inline"></span></section> <span class="md-signature">This article was most recently revised and updated by <a href="/editor/Amy-Tikkanen/6393">Amy Tikkanen</a>.</span><span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article></div> </div></div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":1,"pageId":530603,"pageLength":225,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-130/js/libs/jquery-3.5.0.min.js?v=3.130.14"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-130/dist/topic-page.js?v=3.130.14' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"C","adLeg":"C","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"SMALL","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":false} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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