{"674642":{"#nid":"674642","#data":{"type":"news","title":"Weaker Ocean Currents Lead to Decline in Nutrients for  North Atlantic Ocean Life During Prehistoric Climate Change, Research Shows","body":[{"value":"\u003Cp\u003EGeorgia Tech researchers have finished investigating how the prehistoric weakening of a major ocean current led to a decline in ocean nutrients and negative impacts on North Atlantic ocean life. The results support predictions about how our oceans might react to a changing climate \u2014 and what that means for ocean life.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe North Atlantic ocean is a hub of biological activity, due in large part to the Gulf Stream, which supplies a rich current of nutrients. Scientists have speculated that our changing climate may lead to a decline of nutrients and biological activity in the North Atlantic due to a weakening of the ocean circulation \u2014 but this theory has previously been supported only by models.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ENow, by studying sediments buried at the Gulf Stream\u2019s origin, the team has conducted a first-of-its-kind investigation into the impact of a similar climate-induced decline nearly 13,000 years ago, when Earth exited the last ice age.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe paper, \u201c\u003Ca href=\u0022http:\/\/science.org\/doi\/10.1126\/science.adi5543\u0022\u003EA Diminished North Atlantic Nutrient Stream During Younger Dryas Climate Reversal\u003C\/a\u003E\u201d was published in \u003Cem\u003EScience\u003C\/em\u003E this week. Led by \u003Ca href=\u0022https:\/\/jls.eas.gatech.edu\/\u0022\u003E\u003Cstrong\u003EJean Lynch-Stieglitz\u003C\/strong\u003E\u003C\/a\u003E, a professor in the \u003Ca href=\u0022http:\/\/eas.gatech.edu\u0022\u003ESchool of Earth of Atmospheric Sciences\u003C\/a\u003E, the team also included Lynch-Stieglitz\u2019s past students: \u003Cstrong\u003ETyler Vollmer, Shannon Valley,\u003C\/strong\u003E and \u003Cstrong\u003EEric Blackmon\u003C\/strong\u003E, along with \u003Cstrong\u003ESifan Gu \u003C\/strong\u003E(Jiao Tong University School of Oceanography), and \u003Cstrong\u003EThomas Marchitto \u003C\/strong\u003E(University of Colorado, Boulder).\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cThe research tests a concept that has previously only been explored in theory and models,\u201d Lynch-Stieglitz says. \u201cThe large-scale Atlantic overturning circulation provides the nutrients that underly biological productivity in the North Atlantic.\u201d\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESince the current is expected to continue weakening over the next century as a result of greenhouse gas emissions, researchers anticipate that the North Atlantic will receive fewer and fewer nutrients.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cThis concept has real-world implications for the future health of the oceans and fisheries,\u201d Lynch-Stieglitz explains. Impacts range from a decline in fish populations to potentially impacting the amount of CO2 the ocean can uptake.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cThe dramatic climate changes the Earth has experienced in the past can help us understand what parts of the Earth system are vulnerable to change, and help us evaluate ideas about the impacts of the ongoing climate change,\u201d she adds.\u003C\/p\u003E\r\n\r\n\u003Ch3\u003E\u003Cstrong\u003EAn unlikely mystery\u003C\/strong\u003E\u003C\/h3\u003E\r\n\r\n\u003Cp\u003EThe team studied the Younger Dryas, a period of time during the transition out of the last ice age when there was a weakening of the Atlantic circulation. By examining how the nutrient stream changed when circulation weakened in the past, the researchers hoped to better understand what we may expect from today\u0027s warming oceans.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EHowever, the team didn\u2019t initially set out with this goal in mind \u2014 the work began as an undergraduate research project with an intriguing mystery. Eric Blackmon, then a student in Lynch-Stieglitz\u2019s lab, was interested in investigating the disappearance of a species of plankton from the North Atlantic Ocean during the last ice age.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cThe outcome of this study was puzzling,\u201d Lynch-Stieglitz recalls. The team decided to use a rarely used technique to better understand the results. The method of reconstructing seawater oxygen concentration produced an unusually clear record of how oxygen concentration in the seawater had changed through time.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cOur team realized that when combined with an earlier reconstruction of seawater chemistry, the technique provided key information on the history and mechanisms of nutrient delivery into the North Atlantic Ocean,\u201d Lynch-Stieglitz says. \u201cWe set out to answer a small question, and along the way discovered our data has broader implications than we anticipated.\u201d\u003C\/p\u003E\r\n\r\n\u003Ch3\u003E\u003Cstrong\u003EBeautiful tiny shells\u003C\/strong\u003E\u003C\/h3\u003E\r\n\r\n\u003Cp\u003EWith this new technique, the team analyzed layers of sediment in the Florida Straits, a narrow passage between the Florida Keys and Cuba, where the Gulf of Mexico and the Atlantic Ocean meet. By coring into these layers and taking a cylindrical sample, \u201cthe layers of accumulating sediments provide an environmental history at the site,\u201d Lynch-Stieglitz explains. In this instance, \u201cwe looked at how the shells of single-celled organisms called \u003Cem\u003Eforaminifera\u003C\/em\u003E changed with time.\u201d Because \u003Cem\u003Eforaminifera \u003C\/em\u003Elive on the ocean floor, their shells accumulate within each layer of sediment, preserving important chemical signatures that can be used to reconstruct the chemistry of the ocean in which they resided.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cIt is pretty amazing that ocean chemistry of the past can be reconstructed in such detail using beautiful, tiny shells,\u201d Lynch-Stieglitz says.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe research showed that during the Younger Dryas, as the overturning circulation weakened, nutrients in the Gulf Stream decreased and the amount of oxygen in the Florida Straits increased. The team also found that as the nutrient stream decreased, the amount of biological productivity in the North Atlantic decreased as well.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cThe study represents an important development of the carbon isotope-based proxy for past oxygen concentrations,\u201d Lynch-Stieglitz says. \u201cThe record is very clean, and the magnitude and timing of the changes in dissolved oxygen are mirrored to an astonishing degree in the phosphate reconstruction.\u201d\u003Cstrong\u003E \u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Ch3\u003E\u003Cstrong\u003EBeyond climate\u003C\/strong\u003E\u003C\/h3\u003E\r\n\r\n\u003Cp\u003EBeyond these findings about how the ocean works, the team\u2019s study of \u003Cem\u003Eforaminifera \u003C\/em\u003Ealso provides new ways to understand how nutrients are cycled around the ocean, and how we investigate this. These windows into\u0026nbsp;how Earth\u2019s oceans changed in the past provide a critical tool for testing models, letting us better predict how our oceans and the resources they provide may respond to climate change in the future.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cThe physical changes in the earth system can have profound changes on life in the ocean, and far-reaching impacts,\u201d Lynch-Stieglitz notes. \u201cClimate change is about more than climate,\u201d\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cem\u003EThis study was supported by National Science Foundation grant OCE-1459563 (J.L.-S.) and National Science Foundation grant OCE-1851900 (J.L.-S.).\u003C\/em\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cem\u003EDOI: \u003Ca href=\u0022science.org\/doi\/10.1126\/science.adi5543\u0022\u003Escience.org\/doi\/10.1126\/science.adi5543\u003C\/a\u003E\u003C\/em\u003E\u003C\/p\u003E\r\n","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EIn a first-of-its kind study, Georgia Tech researchers have investigated how the prehistoric weakening of a major ocean current led to a decline in ocean nutrients and negative impacts on North Atlantic ocean life. The results support predictions about how our oceans might react to a changing climate \u2014 and what that means for ocean life.\u003C\/p\u003E\r\n","format":"limited_html"}],"field_summary_sentence":[{"value":" The study, lead by researchers at Georgia Tech, uncovers how weakening prehistoric ocean currents impacted North Atlantic nutrient levels and ocean life,\u00a0supporting predictions about how today\u0027s oceans might react to a changing climate."}],"uid":"35599","created_gmt":"2024-05-10 14:04:26","changed_gmt":"2024-05-10 18:14:21","author":"sperrin6","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2024-05-10T00:00:00-04:00","iso_date":"2024-05-10T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"673977":{"id":"673977","type":"image","title":"Taking a sediment core from the Florida Straits.","body":null,"created":"1715350068","gmt_created":"2024-05-10 14:07:48","changed":"1715350068","gmt_changed":"2024-05-10 14:07:48","alt":"Taking a sediment core from the Florida Straits.","file":{"fid":"257439","name":"SedimentCore.jpeg","image_path":"\/sites\/default\/files\/2024\/05\/10\/SedimentCore.jpeg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2024\/05\/10\/SedimentCore.jpeg","mime":"image\/jpeg","size":230926,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2024\/05\/10\/SedimentCore.jpeg?itok=jD1DUnzB"}},"673975":{"id":"673975","type":"image","title":"\u201cIt is pretty amazing that ocean chemistry of the past can be reconstructed in such detail using beautiful, tiny shells,\u201d Lynch-Stieglitz says.","body":null,"created":"1715350068","gmt_created":"2024-05-10 14:07:48","changed":"1715350068","gmt_changed":"2024-05-10 14:07:48","alt":"\u201cIt is pretty amazing that ocean chemistry of the past can be reconstructed in such detail using beautiful, tiny shells,\u201d Lynch-Stieglitz says.","file":{"fid":"257437","name":"TinyShells2.jpeg","image_path":"\/sites\/default\/files\/2024\/05\/10\/TinyShells2.jpeg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2024\/05\/10\/TinyShells2.jpeg","mime":"image\/jpeg","size":279559,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2024\/05\/10\/TinyShells2.jpeg?itok=Z3_5uqqN"}},"673976":{"id":"673976","type":"image","title":"Foraminifera shells accumulated within each layer of sediment, preserving important chemical signatures.","body":null,"created":"1715350068","gmt_created":"2024-05-10 14:07:48","changed":"1715350068","gmt_changed":"2024-05-10 14:07:48","alt":"Foraminifera shells accumulated within each layer of sediment, preserving important chemical signatures.","file":{"fid":"257438","name":"TinyBeautifulShells.jpeg","image_path":"\/sites\/default\/files\/2024\/05\/10\/TinyBeautifulShells.jpeg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2024\/05\/10\/TinyBeautifulShells.jpeg","mime":"image\/jpeg","size":134491,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2024\/05\/10\/TinyBeautifulShells.jpeg?itok=9_cMFy6e"}}},"media_ids":["673977","673975","673976"],"related_links":[{"url":"https:\/\/www.science.org\/doi\/10.1126\/science.adi5543","title":"A diminished North Atlantic nutrient stream during Younger Dryas climate reversal"}],"groups":[{"id":"1278","name":"College of Sciences"},{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[{"id":"154","name":"Environment"},{"id":"146","name":"Life Sciences and Biology"}],"keywords":[{"id":"187915","name":"go-researchnews"},{"id":"192254","name":"cos-climate"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EWritten by \u003Ca href=\u0022mailto: sperrin6@gatech.edu\u0022\u003ESelena Langner\u003C\/a\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}