{"id":76358,"date":"2013-04-22T15:29:00","date_gmt":"2013-04-22T19:29:00","guid":{"rendered":"https:\/\/today.uconn.edu\/?p=76358"},"modified":"2013-04-25T09:31:10","modified_gmt":"2013-04-25T13:31:10","slug":"new-geochemical-method-highlights-links-between-terrestrial-climate-and-atmospheric-carbon-dioxide","status":"publish","type":"post","link":"https:\/\/today.uconn.edu\/2013\/04\/new-geochemical-method-highlights-links-between-terrestrial-climate-and-atmospheric-carbon-dioxide\/","title":{"rendered":"New Geochemical Method Highlights Links Between Terrestrial Climate and Atmospheric Carbon Dioxide"},"content":{"rendered":"
\"Michael<\/a>
Michael Hren, assistant professor of integrative geoscience. (Ariel Dowski ’14 (CLAS)\/UConn Photo)<\/figcaption><\/figure>\n

Nearly 34 million years ago, the Earth underwent a transformation from a warm, high-carbon dioxide \u201cgreenhouse\u201d state to a lower-CO2<\/sub>, variable climate\u00a0similar to\u00a0the modern \u201cicehouse\u201d world. Massive ice sheets grew across the Antarctic continent, major animal groups shifted, and ocean temperatures decreased by as much as 5 degrees.<\/p>\n

But studies of how this drastic change affected temperatures on land have had mixed results. Some show no appreciable terrestrial climate change; others find cooling of up to 8 degrees and large changes in seasonality.<\/p>\n

Now a group of American and British scientists have used a new chemical technique to measure the change in terrestrial temperature associated with this shift in global atmospheric CO2 <\/sub>concentrations.<\/p>\n

Their results suggest a drop of as much as 10 degrees for fresh water during the warm season and 6 degrees for the atmosphere in the North Atlantic, giving further evidence that the concentration of atmospheric carbon dioxide and Earth\u2019s surface temperature are inextricably linked.<\/p>\n

\u201cOne of the key principles of geology is that the past is the key to the present: records of past climate inform us of how the Earth system functions,\u201d says Michael Hren, assistant professor of chemistry and geosciences at the University of Connecticut and the study\u2019s lead author. \u201cBy understanding past climate transitions, we can better understand the present, and predict impacts for the future.\u201d<\/p>\n

The transition between the Late Eocene and the Oligocene epochs (between 34 million and 33.5 million years ago) was triggered in part, the authors write in their April 22 paper in <\/a>Proceedings of the National Academy of Sciences<\/a>,<\/i> by changes in the concentration of atmospheric CO2<\/sub> that enabled ice to build up on the Antarctic continent.<\/p>\n

Ice-sheet growth, coupled with favorable changes in the Earth\u2019s orbit, pushed the planet past a climatic tipping point and led to both the rapid buildup of a permanent ice sheet in the Antarctic and much larger changes in global climate, says Hren.<\/p>\n

But much of what is known about this time period\u2019s climate comes from cores drilled deep in the ocean, Hren says. There, organic and inorganic remains of ancient marine creatures retain chemical signatures of ocean temperatures when they were alive.<\/p>\n

\"Carbonate<\/a>
Carbonate shells of the freshwater gastropod Viviparus lentus from the Hampshire Basin, UK. (Photo courtesy of Michael Hren)<\/figcaption><\/figure>\n

Now, Hren and his colleagues have used a recently-developed \u201cclumped isotope thermometer\u201d to examine terrestrial fossil shells from this time period. The team collected fossilized snails from the Isle of Wight, Great Britain, and looked for not just the kind and number of carbon and oxygen isotopes present, but how they were bound together.<\/p>\n

The abundance of bonds containing heavy isotopes of both oxygen and carbon are temperature-dependent, so they can give a reliable picture of the terrestrial climate.<\/p>\n

\u201cThe unique thing here is that we\u2019re using isotopologues to measure the temperature that these snails experienced, and relating that to the climate during this interval of declining CO2<\/sub>,\u201d Hren says.<\/p>\n

What makes their results so important, says Hren, is that it\u2019s further evidence that CO2 <\/sub>is linked not only to climate by way of the vast oceans and their temperature, but by terrestrial temperatures, too.<\/p>\n

\u201cIt gives further evidence of the close links between atmospheric CO2<\/sub> and temperature, but also shows how heterogeneous this climate change may be on land,\u201d he adds.<\/p>\n

Studies have shown that before this drastic cooling event, Earth\u2019s atmosphere contained 1,000 parts per million (ppm) of CO2<\/sub> or more, and by the end of the transition, it was likely lower than 600-700 ppm. Some predictions, notes Hren, suggest that Earth\u2019s current CO2<\/sub> concentrations, currently at close to 400 ppm and climbing, could increase to nearly 1,000 ppm in the next 100 years.<\/p>\n

If that turns out to be the case, it\u2019s likely that temperature changes on the scale of the Eocene to Oligocene could occur \u2013 but in the other direction, toward a much warmer climate that could again fundamentally alter living things on Earth.<\/p>\n

\u201cWe are on a path to fundamentally alter our global climate state,\u201d says Hren. \u201cThese data definitely give you pause.\u201d<\/p>\n

The other members of the research group are: Nathan Dale Sheldon and Kyger C. Lohmann of the University of Michigan; Stephen T. Grimes and Melanie Bugler of Plymouth University; Margaret E. Collinson of Royal Holloway University; and Jerry J. Hooker of the Natural History Museum.<\/p>\n","protected":false},"excerpt":{"rendered":"

In a new study led by UConn’s Michael Hren, evidence from 34 million years ago lend weight to predictions of future profound climate change.<\/p>\n","protected":false},"author":37,"featured_media":76549,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_crdt_document":"","wds_primary_category":0,"wds_primary_series":0,"wds_primary_attribution":0,"footnotes":""},"categories":[1],"tags":[],"magazine-issues":[],"coauthors":[63],"class_list":["post-76358","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"pp_statuses_selecting_workflow":false,"pp_workflow_action":"current","pp_status_selection":"publish","acf":[],"publishpress_future_action":{"enabled":false,"date":"2026-05-27 10:07:54","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/76358","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/users\/37"}],"replies":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/comments?post=76358"}],"version-history":[{"count":5,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/76358\/revisions"}],"predecessor-version":[{"id":76611,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/76358\/revisions\/76611"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media\/76549"}],"wp:attachment":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media?parent=76358"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/categories?post=76358"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/tags?post=76358"},{"taxonomy":"magazine-issue","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/magazine-issues?post=76358"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/coauthors?post=76358"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}