{"id":34931,"date":"2026-01-22T16:47:51","date_gmt":"2026-01-22T11:02:51","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=34931"},"modified":"2026-01-22T16:47:54","modified_gmt":"2026-01-22T11:02:54","slug":"scientists-solve-66-million-year-old-mystery-of-how-earths-greenhouse-age-ended","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/scientists-solve-66-million-year-old-mystery-of-how-earths-greenhouse-age-ended\/","title":{"rendered":"Scientists solve 66 million-year-old mystery of how Earth\u2019s greenhouse age ended"},"content":{"rendered":"\n

Experts discovered that concentrations of calcium in the sea dropped by more than half across the last 66 million years, which likely caused Earth\u2019s massive drop in temperature<\/em><\/strong><\/p>\n\n\n\n

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UNIVERSITY OF SOUTHAMPTON<\/sup><\/em><\/figcaption><\/figure>\n\n\n\n

A 66 million-year-old mystery behind how our planet transformed from a tropical greenhouse to the ice-capped world of today has been unravelled by scientists.<\/p>\n\n\n\n

Their new study has revealed that Earth\u2019s massive drop in temperature after the dinosaurs went extinct could have been caused by a large decrease in calcium levels in the ocean.<\/p>\n\n\n\n

An international team of experts led by the University of Southampton discovered that concentrations of calcium in the sea dropped by more than half across the last 66 million years.<\/p>\n\n\n\n

The study, published in\u00a0Proceeding of the National Academy of Sciences (PNAS)<\/a>,\u00a0<\/em>showed that the dramatic calcium shift may have sucked carbon dioxide \u2013 a major greenhouse gas \u2013 out of the atmosphere, driving global cooling.<\/p>\n\n\n\n

Lead author Dr David Evans, an ocean and earth scientist from Southampton, said that large changes in the composition of seawater chemistry may have been a key driver for climate change.<\/p>\n\n\n\n

He added: “Our results show that dissolved calcium levels were twice as high at the start of the Cenozoic Era, shortly after dinosaurs roamed the planet, compared to today.<\/p>\n\n\n\n

\u201cWhen these levels were high, the oceans worked differently, acting to store less carbon in seawater and releasing carbon dioxide into the air.<\/p>\n\n\n\n

\u201cAs those levels decreased, CO2<\/sub> was sucked out of the atmosphere, and the Earth\u2019s temperature followed, dropping our climate by as much as 15 to 20 degrees Celsius.”<\/p>\n\n\n\n

The Southampton researchers behind the study worked in collaboration with scientists from China, the USA, Israel, Denmark, Germany, Belgium and Netherlands.<\/p>\n\n\n\n

They used fossilised remains of tiny sea creatures dug up from sediments at the seafloor to construct the most detailed record of ocean chemistry to date.<\/p>\n\n\n\n

The chemical composition of the fossils, called foraminifera, showed a close link between the amount of calcium in seawater and the level of carbon dioxide in the air.<\/p>\n\n\n\n

Using computer-made models, the team showed that high levels of calcium change how much carbon is \u201cfixed\u201d by marine life, such as corals and plankton, said Dr Evans.<\/p>\n\n\n\n

This effectively locked it away from the ocean and atmosphere by storing it in sediments on the seafloor.<\/p>\n\n\n\n

As dissolved calcium levels decreased across millions of years, it altered how these organisms produced and buried calcium carbonate on the seafloor, added co-author Dr Xiaoli Zhou of Tongji University in China.<\/p>\n\n\n\n

She added: \u201cThe process effectively pulls carbon dioxide out of the atmosphere and locks it away.<\/p>\n\n\n\n

\u201cThis shift could have changed the composition of the atmosphere, effectively turning down the planet\u2019s thermostat.\u201d<\/p>\n\n\n\n

The experts also revealed that the drop in calcium closely matched the slowing down of seafloor spreading \u2013 the volcanic process that continuously creates new ocean floors.<\/p>\n\n\n\n

As the rate of seafloor production slowed, the chemical exchange between the rocks and sea water changed, leading to a gradual decline in dissolved calcium concentrations, said co-author Professor Yair Rosenthal from Rutgers University, USA.<\/p>\n\n\n\n

He added: “Seawater chemistry is typically viewed as something that responds to other factors that lead to changes in our climate, rather than being the cause itself.<\/p>\n\n\n\n

\u201cBut our new evidence suggests that we must look to changing seawater chemistry to understand our planet\u2019s climate history.<\/p>\n\n\n\n

\u201cIt may be that changes in these deep Earth processes are ultimately responsible for much of the large climatic shifts that have taken place over geological time.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

A 66 million-year-old mystery behind how our planet transformed from a tropical greenhouse to the ice-capped world of today has been unravelled by scientists.<\/p>\n","protected":false},"author":2,"featured_media":34933,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[60],"tags":[],"class_list":["post-34931","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-earth-science"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-200x200.webp",200,200,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-675x338.webp",675,338,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-600x350.webp",600,350,true],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-600x350.webp",600,350,true],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended.webp",700,350,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-550x350.webp",550,350,true],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-95x65.webp",95,65,true],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-640x350.webp",640,350,true],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-96x96.webp",96,96,true],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2026\/01\/mystery-of-earths-greenhouse-age-ended-150x75.webp",150,75,true]},"author_info":{"info":["RevoScience"]},"category_info":"Earth Science<\/a>","tag_info":"Earth Science","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/34931","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=34931"}],"version-history":[{"count":1,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/34931\/revisions"}],"predecessor-version":[{"id":34934,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/34931\/revisions\/34934"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/34933"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=34931"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=34931"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=34931"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}