Global warming | Definition, Causes, Effects, Solutions, & Facts

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border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/science/global-warming">global warming</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/science/global-warming">Introduction & Top Questions</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref274818"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/global-warming/Climatic-variation-since-the-last-glaciation">Climatic variation since the last glaciation</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref274819"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/global-warming/Causes-of-global-warming">Causes of global warming</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref274820"><a class="w-100 link-gray-900" href="/science/global-warming/Causes-of-global-warming#ref274820">The greenhouse effect</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274821"><a class="w-100 link-gray-900" href="/science/global-warming/Radiative-forcing">Radiative forcing</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274822"><a class="w-100 link-gray-900" href="/science/global-warming/Radiative-forcing#ref274822">The influences of human activity on climate</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref274823" class="has-children"><a class="w-100 link-gray-900" href="/science/global-warming/Radiative-forcing#ref274823">Greenhouse gases</a><ul class="list-unstyled" data-level="h4"><li data-target="#ref274824"><a class="w-100 link-gray-900" href="/science/global-warming/Radiative-forcing#ref274824">Water vapour</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref274825"><a class="w-100 link-gray-900" href="/science/global-warming/Carbon-dioxide">Carbon dioxide</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref274826"><a class="w-100 link-gray-900" href="/science/global-warming/Carbon-dioxide#ref274826">Methane</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref274827"><a class="w-100 link-gray-900" href="/science/global-warming/Surface-level-ozone-and-other-compounds">Surface-level ozone and other compounds</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref274828"><a class="w-100 link-gray-900" href="/science/global-warming/Surface-level-ozone-and-other-compounds#ref274828">Nitrous oxides and fluorinated gases</a></li></ul></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274829"><a class="w-100 link-gray-900" href="/science/global-warming/Surface-level-ozone-and-other-compounds#ref274829">Aerosols</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274830"><a class="w-100 link-gray-900" href="/science/global-warming/Land-use-change">Land-use change</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274831"><a class="w-100 link-gray-900" href="/science/global-warming/Land-use-change#ref274831">Stratospheric ozone depletion</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274832"><a class="w-100 link-gray-900" href="/science/global-warming/Land-use-change#ref274832">Natural influences on climate</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref274833"><a class="w-100 link-gray-900" href="/science/global-warming/Volcanic-aerosols">Volcanic aerosols</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274834"><a class="w-100 link-gray-900" href="/science/global-warming/Volcanic-aerosols#ref274834">Variations in solar output</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274835"><a class="w-100 link-gray-900" href="/science/global-warming/Variations-in-Earths-orbit">Variations in Earth’s orbit</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274836"><a class="w-100 link-gray-900" href="/science/global-warming/Feedback-mechanisms-and-climate-sensitivity">Feedback mechanisms and climate sensitivity</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref274837"><a class="w-100 link-gray-900" href="/science/global-warming/Feedback-mechanisms-and-climate-sensitivity#ref274837">Water vapour feedback</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274838"><a class="w-100 link-gray-900" href="/science/global-warming/Feedback-mechanisms-and-climate-sensitivity#ref274838">Cloud feedbacks</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274839"><a class="w-100 link-gray-900" href="/science/global-warming/Feedback-mechanisms-and-climate-sensitivity#ref274839">Ice albedo feedback</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274840"><a class="w-100 link-gray-900" href="/science/global-warming/Feedback-mechanisms-and-climate-sensitivity#ref274840">Carbon cycle feedbacks</a></li></ul></li></ul></div></li><li data-target="#ref274841"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/global-warming/Climate-research">Climate research</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref274842"><a class="w-100 link-gray-900" href="/science/global-warming/Climate-research#ref274842">Modern observations</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274843"><a class="w-100 link-gray-900" href="/science/global-warming/Climate-research#ref274843">Prehistorical climate records</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274844"><a class="w-100 link-gray-900" href="/science/global-warming/Theoretical-climate-models">Theoretical climate models</a></li></ul></div></li><li data-target="#ref274845"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/global-warming/Potential-effects-of-global-warming">Potential effects of global warming</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref274846"><a class="w-100 link-gray-900" href="/science/global-warming/Potential-effects-of-global-warming#ref274846">Simulations of future climate change</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref274847"><a class="w-100 link-gray-900" href="/science/global-warming/Potential-effects-of-global-warming#ref274847">Patterns of warming</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274848"><a class="w-100 link-gray-900" href="/science/global-warming/Potential-effects-of-global-warming#ref274848">Precipitation patterns</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274849"><a class="w-100 link-gray-900" href="/science/global-warming/Potential-effects-of-global-warming#ref274849">Regional predictions</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274850"><a class="w-100 link-gray-900" href="/science/global-warming/Ice-melt-and-sea-level-rise">Ice melt and sea level rise</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274851"><a class="w-100 link-gray-900" href="/science/global-warming/Ice-melt-and-sea-level-rise#ref274851">Ocean circulation changes</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref274852"><a class="w-100 link-gray-900" href="/science/global-warming/Ice-melt-and-sea-level-rise#ref274852">Tropical cyclones</a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274853"><a class="w-100 link-gray-900" href="/science/global-warming/Environmental-consequences-of-global-warming">Environmental consequences of global warming</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref274854"><a class="w-100 link-gray-900" href="/science/global-warming/Socioeconomic-consequences-of-global-warming">Socioeconomic consequences of global warming</a></li></ul></div></li></ul> <a class="toc-extra-link link-gray-900" 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In 1938 the Grinnell Glacier filled the entire area at the bottom of the image. By 2006 it had largely disappeared from this view.</span></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 class="topic-header"> <div class="d-flex align-items-top justify-content-between"> <div class="d-flex flex-column"> <div> <div> <h1>global warming</h1></div> </div> <div class="topic-identifier font-16 font-md-20">Earth science</div> </div> </div> <div class="d-none d-sm-flex flex-row"> <div class="mr-10 mb-15"> <button class="ai-ask-button btn btn-sm border-2 btn-outline-red-400 border-red-400 btn-sm btn-outline-red-400 border-red-400 px-sm-5 px-md-10 js-inline-ai-ask-button"> Ask the Chatbot a Question </button> </div> <div class="d-block md-topic-tools qa-action-buttons mb-15" data-topic-id="235402"> <button class="js-tooltip btn btn-sm btn-outline-blue border pr-10 border-2 text-nowrap" > <em class="material-icons md-icon ml-n10 my-n5 mr-5" data-icon="more_vert"></em> More Actions </button> <div class="md-more-popover popover popover-sm p-0 font-14 z-1"> <div> <button class="js-print-modal-button js-modal gtm-topic-tool btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=235402] .md-print-modal" > <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="print"></em> Print </button> <div class="md-print-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif d-flex align-items-center pb-15 border-bottom"> <em class="material-icons text-blue mr-10">print</em> Print </div> <div class="mt-20 mb-10"> Please select which sections you would like to print: </div> <form action="/print/article/235402" method="post" target="_blank" rel="noopener"> <div class="print-box-items"> <ul class="list-unstyled"> <li><label><input class="mr-10" type="checkbox" name="sequence[]" value="0">Table Of Contents</label></li> </ul> </div> <input type="submit" class="btn btn-blue md-disabled" value="Print" /> </form> </div> </div> </div> <div> <button class="js-modal qa-cite-modal-button btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=235402] .md-cite-modal"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="verified"></em> Cite </button> <div class="md-cite-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif d-flex align-items-center pb-15 border-bottom mb-15"> <em class="material-icons text-blue mr-10">verified</em>Cite </div> <div class="font-serif"> While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. </div> <div class="label mt-20 mb-10">Select Citation Style</div> <select class="js-citation-format-select form-select"> <option selected value="mla">MLA</option> <option value="apa">APA</option> <option value="chicago">Chicago Manual of Style</option> </select> <div class="citation font-serif border rounded p-15 mt-20" data-authors="Mann, Michael E." data-authors-initial="Mann, M.E." data-title="global warming" data-published-date="14 Feb. 2025" data-url="https://www.britannica.com/science/global-warming" > <div class="citation-text"></div> </div> <button class="js-copy-citation-button mt-20 btn btn-xs btn-outline-blue border shadow-sm pr-10" > <em class="material-icons md-icon ml-n10 my-n5 mr-5" data-icon="file_copy"></em> <span class="js-citation-status-text">Copy Citation</span> </button> </div> </div> </div> <div> <button class="js-share-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=235402] .md-share-modal"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="share"></em> Share </button> <div class="md-share-modal size-lg d-none qa-share-modal"> <div class="md-modal-body"> <div class="h2 font-serif d-flex align-items-center pb-15 border-bottom"> <em class="material-icons text-blue mr-10" data-icon="share"></em> Share </div> <div class="label my-20">Share to social media</div> <div class="md-social-toolbar-circle d-flex align-items-start inverted" data-value="share" title="global warming" data-url="https://www.britannica.com/science/global-warming" > <a class="social-icon facebook justify-content-center d-flex align-items-center align-self-center" data-provider="facebook" href="https://www.facebook.com/BRITANNICA/" target="_blank" rel="noopener"><span>Facebook</span></a> <a class="social-icon x justify-content-center d-flex align-items-center align-self-center" data-provider="x" href="https://x.com/britannica" target="_blank" rel="noopener"><span>X</span></a> </div> <div class="label pt-20 mt-20 mb-5 border-top">URL</div> <a class="font-serif text-truncate d-inline-block" href="https://www.britannica.com/science/global-warming">https://www.britannica.com/science/global-warming</a> </div> </div> </div> <div> <button class="js-feedback-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal=".md-feedback-modal"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="message"></em> Feedback </button> </div> <div> <button class="qa-external-website-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=235402] .md-websites-modal"> <em class="material-icons md-icon ml-n10 mr-5" data-icon="link"></em> External Websites </button> </div> </div> <div class="md-feedback-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif pb-15 border-bottom"> Feedback </div> <form method="post" action="/submission/feedback/235402"> <div class="my-20"> Corrections? 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Mann</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Associate Professor of Meteorology, Pennsylvania State University, University Park.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Michael E. Mann</span></div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 qa-editor-popup font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2025-02-14T00:00:00CST" >Feb 14, 2025</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/global-warming/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn btn-sm border-2 btn-outline-red-400 border-red-400 module-spacing js-inline-ai-ask-button p-10 ml-5"> Ask the Chatbot </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Key People: </dt> <dd><a href="/biography/Klaus-Hasselmann" topicid="2197506">Klaus Hasselmann</a></dd> <dd><a href="/biography/Tim-Flannery" topicid="1376985">Tim Flannery</a></dd> <dd><a href="/biography/Roger-Angel" topicid="1735165">Roger Angel</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/procon/climate-change-debate" topicid="2256566">Climate Change</a></dd> <dd><a href="/topic/global-warming-policy" topicid="2222532">global warming policy</a></dd> <dd><a href="/science/ocean-warming" topicid="1750949">ocean warming</a></dd> <dd><a href="/science/anthropogenic-climate-change" topicid="1963898">anthropogenic climate change</a></dd> <dd><a href="/science/global-cooling" topicid="682393">global cooling</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/global-warming"> See all related content </a> </div> </div> </div> </div><script type="application/ld+json"> { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type" : "Question", "name" : "<div>How does global warming work?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "Human activity affects global surface <a href=\"https:\/\/www.britannica.com\/science\/temperature\">temperatures<\/a> by changing <a href=\"https:\/\/www.britannica.com\/place\/Earth\">Earth<\/a>\u2019s radiative balance\u2014the \u201Cgive and take\u201D between what comes in during the day and what Earth emits at night. Increases in <a href=\"https:\/\/www.britannica.com\/science\/greenhouse-gas\">greenhouse gases<\/a>\u2014i.e., trace gases such as <a href=\"https:\/\/www.britannica.com\/science\/carbon-dioxide\">carbon dioxide<\/a> and <a href=\"https:\/\/www.britannica.com\/science\/methane\">methane<\/a> that absorb <a href=\"https:\/\/www.britannica.com\/science\/heat\">heat<\/a> <a href=\"https:\/\/www.britannica.com\/science\/energy\">energy<\/a> emitted from Earth\u2019s surface and reradiate it back\u2014generated by <a href=\"https:\/\/www.britannica.com\/money\/industry\">industry<\/a> and <a href=\"https:\/\/www.britannica.com\/technology\/transportation-technology\">transportation<\/a> cause the <a href=\"https:\/\/www.britannica.com\/science\/atmosphere\">atmosphere<\/a> to retain more heat, which increases temperatures and alters <a href=\"https:\/\/www.britannica.com\/science\/precipitation\">precipitation<\/a> patterns. " } } , { "@type" : "Question", "name" : "<div>Where does global warming occur in the atmosphere?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "Global warming, the phenomenon of increasing average air temperatures near Earth\u2019s surface over the past one to two centuries, happens mostly in the <a href=\"https:\/\/www.britannica.com\/science\/troposphere\">troposphere<\/a>, the lowest level of the atmosphere, which extends from Earth\u2019s surface up to a height of 6\u201311 miles. This layer contains most of Earth\u2019s <a href=\"https:\/\/www.britannica.com\/science\/cloud-meteorology\">clouds<\/a> and is where living things and their <a href=\"https:\/\/www.britannica.com\/science\/habitat-biology\">habitats<\/a> and <a href=\"https:\/\/www.britannica.com\/science\/weather\">weather<\/a> primarily occur." } } , { "@type" : "Question", "name" : "<div>Why is global warming a social problem?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "Continued global warming is expected to impact everything from energy use to <a href=\"https:\/\/www.britannica.com\/science\/water\">water<\/a> availability to <a href=\"https:\/\/www.britannica.com\/topic\/crop-agriculture\">crop<\/a> productivity throughout the world. Poor countries and communities with limited abilities to adapt to these changes are expected to suffer disproportionately. Global warming is already being associated with increases in the incidence of severe and extreme weather, heavy <a href=\"https:\/\/www.britannica.com\/science\/flood\">flooding<\/a>, and <a href=\"https:\/\/www.britannica.com\/science\/wildfire\">wildfires<\/a>\u2014phenomena that threaten homes, dams, transportation networks, and other facets of human infrastructure. <a href=\"https:\/\/www.britannica.com\/story\/ipcc-climate-report-says-profound-changes-are-underway--a-lead-author-explains\">Learn more about how the IPCC\u2019s Sixth Assessment Report, released in 2021, describes the social impacts of global warming.<\/a>" } } , { "@type" : "Question", "name" : "<div>Where does global warming affect polar bears?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "<a href=\"https:\/\/www.britannica.com\/animal\/polar-bear\">Polar bears<\/a> live in the <a href=\"https:\/\/www.britannica.com\/place\/Arctic\">Arctic<\/a>, where they use the region\u2019s <a href=\"https:\/\/www.britannica.com\/science\/ice\">ice<\/a> floes as they hunt <a href=\"https:\/\/www.britannica.com\/animal\/seal-mammal\">seals<\/a> and other marine <a href=\"https:\/\/www.britannica.com\/animal\/mammal\">mammals<\/a>. Temperature increases related to global warming have been the most pronounced at the poles, where they often make the difference between frozen and melted ice. Polar bears rely on small gaps in the ice to hunt their prey. As these gaps widen because of continued melting, prey capture has become more challenging for these animals." } } ] } </script> <div class="top-questions qa-accordion d-flex flex-column module-spacing"><div class="font-weight-bold font-14 mb-5"> Top Questions </div><div id="intent-accordion" class="md-intent-accordion"><div class="top-question bg-gray-50 rounded" data-value="1"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>How does global warming work?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>Human activity affects global surface <a href="https://www.britannica.com/science/temperature" class="md-crosslink " data-show-preview="true">temperatures</a> by changing <a href="https://www.britannica.com/place/Earth" class="md-crosslink " data-show-preview="true">Earth</a>’s radiative balance—the “give and take” between what comes in during the day and what Earth emits at night. Increases in <a href="https://www.britannica.com/science/greenhouse-gas" class="md-crosslink " data-show-preview="true">greenhouse gases</a>—i.e., trace gases such as <a href="https://www.britannica.com/science/carbon-dioxide" class="md-crosslink " data-show-preview="true">carbon dioxide</a> and <a href="https://www.britannica.com/science/methane" class="md-crosslink " data-show-preview="true">methane</a> that absorb <a href="https://www.britannica.com/science/heat" class="md-crosslink " data-show-preview="true">heat</a> <a href="https://www.britannica.com/science/energy" class="md-crosslink " data-show-preview="true">energy</a> emitted from Earth’s surface and reradiate it back—generated by <a href="https://www.britannica.com/money/industry" class="md-crosslink " data-show-preview="true">industry</a> and <a href="https://www.britannica.com/technology/transportation-technology" class="md-crosslink " data-show-preview="true">transportation</a> cause the <a href="https://www.britannica.com/science/atmosphere" class="md-crosslink " data-show-preview="true">atmosphere</a> to retain more heat, which increases temperatures and alters <a href="https://www.britannica.com/science/precipitation" class="md-crosslink " data-show-preview="true">precipitation</a> patterns. </p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="2"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>Where does global warming occur in the atmosphere?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>Global warming, the phenomenon of increasing average air temperatures near Earth’s surface over the past one to two centuries, happens mostly in the <a href="https://www.britannica.com/science/troposphere" class="md-crosslink " data-show-preview="true">troposphere</a>, the lowest level of the atmosphere, which extends from Earth’s surface up to a height of 6–11 miles. This layer contains most of Earth’s <a href="https://www.britannica.com/science/cloud-meteorology" class="md-crosslink " data-show-preview="true">clouds</a> and is where living things and their <a href="https://www.britannica.com/science/habitat-biology" class="md-crosslink " data-show-preview="true">habitats</a> and <a href="https://www.britannica.com/science/weather" class="md-crosslink " data-show-preview="true">weather</a> primarily occur.</p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="3"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>Why is global warming a social problem?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>Continued global warming is expected to impact everything from energy use to <a href="https://www.britannica.com/science/water" class="md-crosslink " data-show-preview="true">water</a> availability to <a href="https://www.britannica.com/topic/crop-agriculture" class="md-crosslink " data-show-preview="true">crop</a> productivity throughout the world. Poor countries and communities with limited abilities to adapt to these changes are expected to suffer disproportionately. Global warming is already being associated with increases in the incidence of severe and extreme weather, heavy <a href="https://www.britannica.com/science/flood" class="md-crosslink " data-show-preview="true">flooding</a>, and <a href="https://www.britannica.com/science/wildfire" class="md-crosslink " data-show-preview="true">wildfires</a>—phenomena that threaten homes, dams, transportation networks, and other facets of human infrastructure. <a href="https://www.britannica.com/story/ipcc-climate-report-says-profound-changes-are-underway--a-lead-author-explains" class="md-crosslink " data-show-preview="true">Learn more about how the IPCC’s Sixth Assessment Report, released in 2021, describes the social impacts of global warming.</a></p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="4"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>Where does global warming affect polar bears?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p><a href="https://www.britannica.com/animal/polar-bear" class="md-crosslink " data-show-preview="true">Polar bears</a> live in the <a href="https://www.britannica.com/place/Arctic" class="md-crosslink " data-show-preview="true">Arctic</a>, where they use the region’s <a href="https://www.britannica.com/science/ice" class="md-crosslink " data-show-preview="true">ice</a> floes as they hunt <a href="https://www.britannica.com/animal/seal-mammal" class="md-crosslink " data-show-preview="true">seals</a> and other marine <a href="https://www.britannica.com/animal/mammal" class="md-crosslink " data-show-preview="true">mammals</a>. Temperature increases related to global warming have been the most pronounced at the poles, where they often make the difference between frozen and melted ice. Polar bears rely on small gaps in the ice to hunt their prey. As these gaps widen because of continued melting, prey capture has become more challenging for these animals.</p></div></div></div><button class="show-more-button js-toggle-top-questions btn btn-unstyled font-14 d-flex pr-10 rounded-sm"><em class="material-icons" data-icon="expand_more"></em></button></div></div><div class="bg-gray-50 p-15 rounded module-spacing recent-news d-flex flex-column float-false"> <div> <h2 class="font-weight-bold font-14 m-0 d-inline"> News <span class="text-gray-600">•</span> </h2> <div class="recent-news-item first-recent-news-item d-inline"> <a class="font-14 gtm-ap-news-link" href="https://www.cnn.com/2025/02/10/climate/paris-climate-agreement-breach/index.html" rel="nofollow">Two new studies suggest Paris climate goal is dead. One scientist is going even further</a> <span class="font-14 text-gray-600"> <span>•</span> Feb. 10, 2025, 6:28 AM ET (CNN) <button class="btn btn-link d-inline p-0 font-12 js-toggle-recent-news"> <span class="text-gray-500">...</span><span>(Show more)</span> </button> </span> </div> </div> <div class="rest-of-recent-news-items"> <div class="recent-news-item mt-5"> <a class="font-14 gtm-ap-news-link" href="https://fortune.com/2025/02/06/rat-population-global-warming/" rel="nofollow">Armies of rats are laying waste to cities and the $27 billion-a-year problem is only getting worse</a> <span class="font-14 text-gray-600"> <span>•</span> Feb. 7, 2025, 3:53 AM ET (Fortune) </span> </div> <div class="recent-news-item mt-5"> <a class="font-14 gtm-ap-news-link" href="https://www.sciencealert.com/claim-2-degree-target-is-dead-triggers-debate-over-climate-scenarios" rel="nofollow">Claim '2 Degree Target Is Dead' Triggers Debate Over Climate Scenarios</a> <span class="font-14 text-gray-600"> <span>•</span> Feb. 6, 2025, 4:51 AM ET (ScienceAlert) </span> </div> <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><p class="topic-paragraph"><strong><span id="ref837836"></span>global warming</strong>, the phenomenon of increasing average <a href="https://www.britannica.com/science/air" class="md-crosslink autoxref " data-show-preview="true">air</a> <span id="ref979216"></span><a href="https://www.britannica.com/science/temperature" class="md-crosslink " data-show-preview="true">temperatures</a> near the surface of <span id="ref979215"></span><a href="https://www.britannica.com/place/Earth" class="md-crosslink " data-show-preview="true">Earth</a> over the past one to two centuries. Climate scientists have since the mid-20th century gathered detailed observations of various <a href="https://www.britannica.com/science/weather" class="md-crosslink " data-show-preview="true">weather</a> phenomena (such as temperatures, <a href="https://www.britannica.com/science/precipitation" class="md-crosslink " data-show-preview="true">precipitation</a>, and storms) and of related influences on <span id="ref837937"></span><a href="https://www.britannica.com/science/climate-meteorology" class="md-crosslink " data-show-preview="true">climate</a> (such as <a href="https://www.britannica.com/science/ocean-current" class="md-crosslink " data-show-preview="true">ocean currents</a> and the atmosphere’s chemical composition). These data indicate that Earth’s climate has changed over almost every conceivable timescale since the beginning of geologic time and that <a href="https://www.britannica.com/topic/human-being" class="md-crosslink " data-show-preview="true">human</a> activities since at least the beginning of the <a href="https://www.britannica.com/event/Industrial-Revolution" class="md-crosslink " data-show-preview="true">Industrial Revolution</a> have a growing influence over the pace and extent of present-day <span id="ref979213"></span><a href="https://www.britannica.com/science/climate-change" class="md-crosslink " data-show-preview="true">climate change</a>.</p><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">Giving voice to a growing <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="conviction" href="https://www.merriam-webster.com/dictionary/conviction" data-type="MW">conviction</a> of most of the scientific <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="community" href="https://www.merriam-webster.com/dictionary/community" data-type="MW">community</a>, the <span id="ref837942"></span><a href="https://www.britannica.com/topic/Intergovernmental-Panel-on-Climate-Change" class="md-crosslink " data-show-preview="true">Intergovernmental Panel on Climate Change</a> (IPCC) was formed in 1988 by the <a href="https://www.britannica.com/topic/World-Meteorological-Organization" class="md-crosslink " data-show-preview="true">World Meteorological Organization</a> (WMO) and the <a href="https://www.britannica.com/topic/United-Nations-Environment-Programme" class="md-crosslink " data-show-preview="true">United Nations Environment Program</a> (UNEP). The IPCC’s Sixth <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="Assessment" href="https://www.merriam-webster.com/dictionary/Assessment" data-type="MW">Assessment</a> Report (AR6), published in 2021, noted that the best estimate of the increase in global average surface temperature between 1850 and 2019 was 1.07 °C (1.9 °F). An IPCC special report produced in 2018 noted that human beings and their activities have been responsible for a worldwide average temperature increase between 0.8 and 1.2 °C (1.4 and 2.2 °F) since preindustrial times, and most of the warming over the second half of the 20th century could be attributed to human activities.</p><span class="marker MOD2 mod-inline"></span><div class="mb-20"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="274995" data-asm-type="infogram"><div class="md-assembly-wrapper card-media" data-type="infogram"><script id="infogram_0__/v9Hlw0G0VlMuF4ZR3lVR" src="https://e.infogram.com/js/dist/embed.js?Itp" type="text/javascript" title="annual global temperature average: 1880–2023"></script></div></figure></div></div><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">AR6 produced a series of global climate <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="predictions" href="https://www.britannica.com/dictionary/predictions" data-type="EB">predictions</a> based on modeling five greenhouse gas emission scenarios that accounted for future emissions, mitigation (severity reduction) measures, and uncertainties in the model projections. Some of the main uncertainties include the precise role of feedback processes and the impacts of industrial pollutants known as <a href="https://www.britannica.com/science/aerosol" class="md-crosslink " data-show-preview="true">aerosols</a>, which may offset some warming. The lowest-emissions scenario, which assumed steep cuts in greenhouse gas emissions beginning in 2015, predicted that the global mean surface temperature would increase between 1.0 and 1.8 °C (1.8 and 3.2 °F) by 2100 relative to the 1850–1900 average. This range stood in stark contrast to the highest-emissions scenario, which predicted that the mean surface temperature would rise between 3.3 and 5.7 °C (5.9 and 10.2 °F) by 2100 based on the assumption that greenhouse gas emissions would continue to increase throughout the 21st century. The intermediate-emissions scenario, which assumed that emissions would stabilize by 2050 before declining gradually, projected an increase of between 2.1 and 3.5 °C (3.8 and 6.3 °F) by 2100.</p><span class="marker MOD3 mod-inline"></span><div class="mb-20"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="274996" data-asm-type="infogram"><div class="md-assembly-wrapper card-media" data-type="infogram"><script id="infogram_0__/CaFkwUw5rIicssnBiUQ2" src="https://e.infogram.com/js/dist/embed.js?Itp" type="text/javascript" title="Global average sea level change: 1880–2023"></script></div></figure></div></div><span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">Many climate scientists agree that significant societal, economic, and ecological damage would result if the global average temperature rose by more than 2 °C (3.6 °F) in such a short time. Such damage would include increased <a href="https://www.britannica.com/science/extinction-biology" class="md-crosslink autoxref " data-show-preview="true">extinction</a> of many plant and animal species, shifts in patterns of <a href="https://www.britannica.com/topic/agriculture" class="md-crosslink " data-show-preview="true">agriculture</a>, and rising sea levels. By 2015 all but a few national governments had begun the process of instituting carbon reduction plans as part of the <span id="ref1274792"></span><a href="https://www.britannica.com/topic/Paris-Agreement-2015" class="md-crosslink " data-show-preview="true">Paris Agreement</a>, a treaty designed to help countries keep global warming to 1.5 °C (2.7 °F) above preindustrial levels in order to avoid the worst of the predicted effects. Whereas authors of the 2018 special report noted that should carbon emissions continue at their present rate, the increase in average near-surface air temperature would reach 1.5 °C sometime between 2030 and 2052, authors of the AR6 report suggested that this <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="threshold" href="https://www.merriam-webster.com/dictionary/threshold" data-type="MW">threshold</a> would be reached by 2041 at the latest. In an ominous sign that the long-term temperature threshold of 1.5 °C could arrive far sooner than expected, global climate monitoring databases reported that the global temperature average for the year 2024 was 1.6 °C above preindustrial levels.</p><span class="marker MOD4 mod-inline"></span><div class="mb-20"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="287609" data-asm-type="infogram"><div class="md-assembly-wrapper card-media" data-type="infogram"><script id="infogram_0__/uMXuvgyWkZpXSa8nhIzw" src="https://e.infogram.com/js/dist/embed.js?Itp" type="text/javascript" title="July temperature anomalies"></script></div></figure></div></div><span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">The AR6 report also noted that the global average <a href="https://www.britannica.com/science/sea-level" class="md-crosslink autoxref " data-show-preview="true">sea level</a> had risen by some 20 cm (7.9 inches) between 1901 and 2018 and that sea level rose faster in the second half of the 20th century than in the first half. It also predicted, again depending on a wide range of scenarios, that the global average sea level would rise by different amounts by 2100 relative to the 1995–2014 average. Under the report’s lowest-emission scenario, sea level would rise by 28–55 cm (11–21.7 inches), whereas, under the intermediate emissions scenario, sea level would rise by 44–76 cm (17.3–29.9 inches). The highest-emissions scenario suggested that sea level would rise by 63–101 cm (24.8–39.8 inches) by 2100.</p><a class="link-module shadow-sm d-block qa-quiz-module" href="/quiz/pop-quiz-18-things-to-know-about-global-warming" data-link-module-iframe-link=""> <img loading="lazy" src="https://cdn.britannica.com/50/112550-050-D7D94E18/Grinnell-Glacier-series-photographs-summit-Mount-Gould-2006.jpg" alt="Combination shot of Grinnell Glacier taken from the summit of Mount Gould, Glacier National Park, Montana in the years 1938, 1981, 1998 and 2006." class="rounded-sm mr-15" width="70" /> <div class="line-clamp clamp-5"> <div class="module-title bg-green">Britannica Quiz</div> <div class="font-weight-semi-bold mt-5">Pop Quiz: 18 Things to Know About Global Warming</div> </div> </a><span class="marker MOD5 mod-inline"></span><span class="marker PREMOD6 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="85040" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/45/91945-050-7219E195/greenhouse-effect-Earth-surface-sunlight-atmosphere-some.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/235402/85040"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/45/91945-050-7219E195/greenhouse-effect-Earth-surface-sunlight-atmosphere-some.jpg"><img src="https://cdn.britannica.com/45/91945-050-7219E195/greenhouse-effect-Earth-surface-sunlight-atmosphere-some.jpg?w=300" alt="greenhouse effect on Earth" data-width="1600" data-height="1472" 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/45/91945-050-7219E195/greenhouse-effect-Earth-surface-sunlight-atmosphere-some.jpg" data-href="/media/1/235402/85040">greenhouse effect on Earth</a><span>The greenhouse effect on Earth. Some incoming sunlight is reflected by Earth's atmosphere and surface, but most is absorbed by the surface, which is warmed. Infrared (IR) radiation is then emitted from the surface. Some IR radiation escapes to space, but some is absorbed by the atmosphere's greenhouse gases (especially water vapour, carbon dioxide, and methane) and reradiated in all directions, some to space and some back toward the surface, where it further warms the surface and the lower atmosphere.</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">The scenarios referred to above depend mainly on future concentrations of certain trace gases, called <span id="ref838021"></span><a href="https://www.britannica.com/science/greenhouse-gas" class="md-crosslink " data-show-preview="true">greenhouse gases</a>, that have been injected into the lower <span id="ref979214"></span><a href="https://www.britannica.com/science/atmosphere" class="md-crosslink " data-show-preview="true">atmosphere</a> in increasing amounts through the burning of <span id="ref1274793"></span><a href="https://www.britannica.com/science/fossil-fuel" class="md-crosslink " data-show-preview="true">fossil fuels</a> for industry, <a href="https://www.britannica.com/technology/transportation-technology" class="md-crosslink " data-show-preview="true">transportation</a>, and residential uses. Modern global warming is the result of an increase in magnitude of the so-called <span id="ref838029"></span><a href="https://www.britannica.com/science/greenhouse-effect" class="md-crosslink " data-show-preview="true">greenhouse effect</a>, a warming of Earth’s surface and lower atmosphere caused by the presence of <span id="ref1274795"></span><a href="https://www.britannica.com/science/water-vapor" class="md-crosslink ">water vapour</a>, <span id="ref887453"></span><a href="https://www.britannica.com/science/carbon-dioxide" class="md-crosslink " data-show-preview="true">carbon dioxide</a>, <span id="ref1274796"></span><a href="https://www.britannica.com/science/methane" class="md-crosslink " data-show-preview="true">methane</a>, <span id="ref1274797"></span><a href="https://www.britannica.com/science/nitrous-oxide" class="md-crosslink " data-show-preview="true">nitrous oxides</a>, and other greenhouse gases. In 2014 the <a href="https://www.britannica.com/topic/Intergovernmental-Panel-on-Climate-Change" class="md-crosslink " data-show-preview="true">IPCC</a> first reported that concentrations of carbon dioxide, methane, and nitrous oxides in the atmosphere <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="surpassed" href="https://www.britannica.com/dictionary/surpassed" data-type="EB">surpassed</a> those found in <a href="https://www.britannica.com/science/ice-core" class="md-crosslink " data-show-preview="true">ice cores</a> dating back 800,000 years.</p><span class="marker MOD6 mod-inline"></span><span class="marker PREMOD7 mod-inline"></span><p class="topic-paragraph">Of all these gases, carbon dioxide is the most important, both for its role in the greenhouse effect and for its role in the human economy. It has been estimated that, at the beginning of the industrial age in the mid-18th century, carbon dioxide concentrations in the atmosphere were roughly 280 parts per million (ppm). By the end of 2022 they had risen to 419 ppm, and, if fossil fuels continue to be burned at current rates, they are projected to reach 550 ppm by the mid-21st century—essentially, a doubling of carbon dioxide concentrations in 300 years.</p><div class="module-spacing"> <DIV class="marketing-INLINE_SUBSCRIPTION marketing-content" data-marketing-id="INLINE_SUBSCRIPTION"><style> .student-promo-banner-wrapper { container-type: inline-size; margin-bottom: 15px; } @container (min-width: 475px) { .student-promo-banner { flex-direction: row; } .student-promo-banner-img-wrapper { margin-bottom: 0; margin-right: 10px; justify-content: flex-start; } .student-promo-banner-text-wrapper { text-align: left; margin-bottom: 0px; margin-left: 10px; } .student-promo-banner-button-wrapper { margin-right: 0; } }</style> <div class="student-promo-banner-wrapper"> <div class="student-promo-banner d-flex flex-column align-items-center bg-blue rounded p-20"> <div class="student-promo-banner-img-wrapper mb-20 mr-0 d-flex justify-content-center"> <img class="rounded" style="max-width: 100px; min-width: 80px" src="https://cdn.britannica.com/marketing/BlueThistle.webp" /> </div> <div class="student-promo-banner-text-wrapper ml-0 mb-10 text-center text-white"> <div class="h2 mb-10">Get Unlimited Access</div> <div class="h4 font-weight-semi-bold">Try Britannica Premium for free and discover more.</div> </div> <div class="student-promo-banner-button-wrapper d-flex justify-content-center align-items-center ml-auto mr-auto"> <a class="btn btn-m btn-orange" href="https://premium.britannica.com/premium-membership/?utm_source=premium&utm_medium=inline-cta&utm_campaign=august-2024">Subscribe</a> </div> </div> </div> </DIV></div><div class="one-good-fact-module"> </div><span class="marker MOD7 mod-inline"></span><span class="marker PREMOD8 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="302845" data-asm-type="video"><div class="md-assembly-wrapper card-media" data-type="video" video-id="256628"><a data-id="256628" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/the-problem-with-an-early-spring/-302845"><img src="https://cdn.britannica.com/28/256628-138-47B44534/the-problem-with-an-early-spring.jpg?w=800&h=450&c=crop" alt="What's the problem with an early spring?" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/i4lj5AoS.m3u8" } ], "image": "https://cdn.britannica.com/28/256628-138-47B44534/the-problem-with-an-early-spring.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/A0ZvEtRT.vtt", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/CFEmyKLX.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="256628">What's the problem with an early spring?</span><span>Is it just me, or did spring come early this year?</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/global-warming/images-videos">See all videos for this article</a></figcaption></figure></div></div><p class="topic-paragraph">A <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="vigorous" href="https://www.britannica.com/dictionary/vigorous" data-type="EB">vigorous</a> debate is in progress over the extent and seriousness of rising surface temperatures, the effects of past and future warming on human life, and the need for action to reduce future warming and deal with its consequences. This article provides an overview of the scientific background related to the subject of global warming. It considers the causes of rising near-surface air temperatures, the influencing factors, the process of climate research and forecasting, and the possible ecological and social impacts of rising temperatures. For an overview of the public policy developments related to global warming occurring since the mid-20th century, <em>see</em> <a href="https://www.britannica.com/topic/global-warming-policy" class="md-crosslink " data-show-preview="true">global warming policy</a>. For a detailed description of Earth’s climate, its processes, and the responses of living things to its changing nature, <em>see</em> <a href="https://www.britannica.com/science/climate-meteorology" class="md-crosslink " data-show-preview="true">climate</a>. For additional background on how Earth’s climate has changed throughout <a href="https://www.britannica.com/science/geologic-time" class="md-crosslink " data-show-preview="true">geologic time</a>, <em>see</em> <a href="https://www.britannica.com/science/climate-change" class="md-crosslink " data-show-preview="true">climatic variation and change</a>. For a full description of Earth’s gaseous envelope, within which climate change and global warming occur, <em>see</em> <a href="https://www.britannica.com/science/atmosphere" class="md-crosslink " data-show-preview="true">atmosphere</a>.</p><span class="marker MOD8 mod-inline"></span></section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-simplify-root"></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> 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":16,"pageId":235402,"pageLength":1116,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-133/js/libs/jquery-3.5.0.min.js?v=3.133.36"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-133/dist/topic-page.js?v=3.133.36' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"B","adLeg":"B","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":true} </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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Global warming | Definition, Causes, Effects, Solutions, & Facts | Britannica