{"id":170,"date":"2017-05-02T16:52:30","date_gmt":"2017-05-02T20:52:30","guid":{"rendered":"https:\/\/www2.whoi.edu\/staff\/khughen\/?page_id=170"},"modified":"2017-06-28T14:21:32","modified_gmt":"2017-06-28T18:21:32","slug":"carbon-cycle","status":"publish","type":"page","link":"https:\/\/www2.whoi.edu\/staff\/khughen\/research\/carbon-cycle\/","title":{"rendered":"Carbon Cycle"},"content":{"rendered":"<h1>Carbon Cycle<\/h1>\n<p>Box model results and paleoclimate observations show that during deglaciation, reductions in deep ocean ventilation may have resulted in synchronous shifts in both climate and atmospheric D<sup>14<\/sup>C (Hughen et al., 1998; 2000). During the Glacial period, box models show that changes in <sup>14<\/sup>C production from geomagnetic field variability, together with Glacial changes in the global carbon cycle, can explain much of the observed D<sup>14<\/sup>C structure over the past 50 cal ka (Hughen et al., 2004).\u00a0 We are also investigating surface ocean D<sup>14<\/sup>C and upwelling in relation to climate changes. A record of coral D<sup>14<\/sup>C from Bermuda revealed remarkably little variability in thermocline ventilation during the Little Ice Age, suggesting that absorbed anthropogenic carbon does not return to the surface at a variable rate despite changing climate conditions (Goodkin et al., 2012). Radiocarbon in a coral from Vietnam reflects variability in the East Asian Winter Monsoon, and shows decreasing variability since the end of the LIA, likely tied to ENSO variability (Goodkin et al., in review). \u00a0In an on-going study, we are measuring D<sup>14<\/sup>C in northern Red Sea corals to investigate deep water mixing and Intermediate Water formation in the Red Sea.\u00a0 Future work is targeting <sup>14<\/sup>C in corals from Sri Lanka to study changes in the Asian Monsoon.<\/p>\n<p>&nbsp;<\/p>\n<div id=\"attachment_177\" style=\"width: 460px\" class=\"wp-caption aligncenter\"><img aria-describedby=\"caption-attachment-177\" loading=\"lazy\" src=\"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-content\/uploads\/sites\/26\/2017\/05\/14C-cycle-Glacial.jpg\" alt=\"\" width=\"450\" height=\"344\" \/><p id=\"caption-attachment-177\" class=\"wp-caption-text\">Changes in the global carbon cycle during Holocene and Glacial periods<\/p><\/div>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div id=\"attachment_179\" style=\"width: 510px\" class=\"wp-caption aligncenter\"><img aria-describedby=\"caption-attachment-179\" loading=\"lazy\" src=\"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-content\/uploads\/sites\/26\/2017\/05\/Red-Sea-circulation_sm.jpg\" alt=\"\" width=\"500\" height=\"544\" \/><p id=\"caption-attachment-179\" class=\"wp-caption-text\">Cold dense surface water in the northern Red Sea sinks and forms Red Sea Intermediate Water in winter.<\/p><\/div>\n<h3>Relevant Publications<\/h3>\n<ul>\n<li>Goodkin N.F., Bolton, A., Karnauskas, K.B., Hughen, K.A., Griffin, S., Phan, K.H., Vo, S.T., Druffel, E.R.M., Decline of East Asian Winter Monsoon Variability since the 18<sup>th<\/sup> Century, <em>Nature Geoscience<\/em> (in review).<\/li>\n<li>Goodkin, N., Druffel, E., Hughen, K., Doney, S., 2012, Two Centuries of Limited Variability in Subtropical North Atlantic Thermocline Ventilation, <em>Nature Communications<\/em> (doi: 10.1038\/ncomms1811).<\/li>\n<li>Hughen, K.A., Lehman, S.J. Southon, J., Overpeck, J.T., Marchal, O., Herring, C., Turnbull, J. 2004, <sup>14<\/sup>C Activity and Global Carbon Cycle Changes Over the Past 50,000 years, <em>Science<\/em> <strong>303<\/strong>, 202-207.<\/li>\n<li>Hughen, K.A., Southon, J.R., Lehman, S.J., Overpeck, J.T., 2000, Synchronous Radiocarbon and Climate Shifts During the Last Deglaciation, <em>Science<\/em> <strong>290<\/strong>, 1951-1954.<\/li>\n<li>Hughen, K.A., Overpeck, J.T., Lehman, S.J., Kashgarian, M., Southon, J., Peterson, L.C., Alley, R., Sigman, D.M., 1998, Deglacial changes in ocean circulation from an extended radiocarbon calibration, <em>Nature <\/em><strong>391<\/strong>, 65-68.<\/li>\n<\/ul>\n<h3>Funding Agencies<\/h3>\n<p>The National Science Foundation under grant number XXX and the National Ocean and Atmospheric Administration under grant number XXX funded this research.<\/p>\n<p><a href=\"http:\/\/www.nsf.gov\"><img loading=\"lazy\" src=\"https:\/\/www2.whoi.edu\/templates\/wp-content\/uploads\/2016\/09\/nsf.png\" alt=\"nsf\" width=\"100\" height=\"100\" \/><\/a><a href=\"http:\/\/www.noaa.gov\"><img loading=\"lazy\" src=\"https:\/\/www2.whoi.edu\/templates\/wp-content\/uploads\/2016\/09\/noaa.png\" alt=\"noaa\" width=\"90\" height=\"89\" \/><\/a><\/p>\n<h3>Partners\/Collaborators<\/h3>\n<ul>\n<li>John Southon, U. of California, Irvine, CA<\/li>\n<li>Scot Lehman, U. of Colorado, Boulder, CO<\/li>\n<li>Jonathan Overpeck, U. Arizona, Tucson, AZ<\/li>\n<li>Nathalie Goodkin, EOS, NTU, Singapore<\/li>\n<li>Ellen Druffel, U. of California, Irvine, CA<\/li>\n<li>Nalaka Ranasinghe, U. of Sri Lanka<\/li>\n<\/ul>\n<h3>Research Papers<\/h3>\n<ul>\n<li><a href=\"#\">A link<\/a><\/li>\n<li><a href=\"#\">Another link<\/a><\/li>\n<li><a href=\"#\">A\u00a0PDF file attachment<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Carbon Cycle Box model results and paleoclimate observations show that during deglaciation, reductions in deep ocean ventilation may have resulted in synchronous shifts in both climate and atmospheric D14C (Hughen et al., 1998; 2000). During the Glacial period, box models show that changes in 14C production from geomagnetic field variability, together with Glacial changes in&hellip;<\/p>\n","protected":false},"author":24,"featured_media":0,"parent":13,"menu_order":7,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/pages\/170"}],"collection":[{"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/comments?post=170"}],"version-history":[{"count":3,"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/pages\/170\/revisions"}],"predecessor-version":[{"id":488,"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/pages\/170\/revisions\/488"}],"up":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/pages\/13"}],"wp:attachment":[{"href":"https:\/\/www2.whoi.edu\/staff\/khughen\/wp-json\/wp\/v2\/media?parent=170"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}