{"id":1420,"date":"2019-02-14T21:05:53","date_gmt":"2019-02-14T21:05:53","guid":{"rendered":"http:\/\/iccinet.org\/?p=1420"},"modified":"2022-07-12T15:20:00","modified_gmt":"2022-07-12T15:20:00","slug":"climate-analogs-cryosphere","status":"publish","type":"post","link":"https:\/\/iccinet.org\/zh\/climate-analogs-cryosphere\/","title":{"rendered":"Climate Analogs &#038; Cryosphere"},"content":{"rendered":"<p><strong>PNAS\nDecember 10: Models Show Abrupt Transition of Climate to Past Geologic States<\/strong><\/p>\n\n\n\n<p><strong>Main\nMessages:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Already in 2030, Earth\u2019s climate will approach that of the\nmid-Pliocene (-3 million years) if current emissions levels continue unabated,\neg RCP8.5 through 2030. <ul><li>Pliocene (&#8211;3 million), temps 2.8\u00b0-4.6\u00b0 above\npre-industrial, with 20+ m. SLR<\/li><\/ul><ul><li>If emissions continue on an RCP8.5 pathway, the global\nclimate reaches an early Eocene state already by 2150.<\/li><\/ul><ul><li>Eocene (&#8211;50 million), temps +14\u00b0\npre-industrial, no ice (Arctic occupied by swampy forests, either no or very\nsmall Antarctic ice sheet).<\/li><\/ul><\/li><li>If emissions instead track current NDCs (eg RCP4.5), climate\nstill reaches a mid-Pliocene state around 2040, but stabilizes at that new\nstate.<ul><li>The accelerated rate of change appears to be faster than\nanything that has occurred globally in the past, even on geologic time scales.<\/li><\/ul><\/li><\/ul>\n\n\n\n<p><strong>Background:<\/strong><\/p>\n\n\n\n<p>Scientists from the University of Wisconsin worked with colleagues at the University of Bristol, Columbia University, University of Leeds, NASA Goddard and NOAA to examine similarities between RCP4.5 and RCP8.5, and several periods of geologic history. These included the Early Eocene, the mid-Pliocene, the Last Interglacial (&#8211;129-116,000 CE), the mid-Holocene (6,000 years ago), pre-industrial, and the mid-1900\u2019s.\u00a0 They used three models: Hadley (HadCM3), NASA-GISS and CCSM.<\/p>\n\n\n\n<p>Across each model, compared to previous eras the Earth\u2019s\nclimate fairly rapidly diverged from recent eras and most closely resembled the\nmid-Pliocene already by 2030 (under RCP8.5) or by 2040 (under RCP4.5). Under the\ngreenhouse gas stabilization scenario of RCP4.5, the climate then stabilizes at\nmid-Pliocene-like conditions; but under the higher greenhouse gas emissions of RCP8.5,\nthe climate continues to warm until it begins to resemble the Eocene in 2100,\nachieving Eocene-like conditions more broadly by 2150. <\/p>\n\n\n\n<p>According to the models, under RCP8.5 these deep-geologic-time\nclimates emerged first from the center of continents, and then expanded outward\nover time. &nbsp;Temperatures rise more\nquickly in these central regions.&nbsp;\nTowards 2200, climates become temperate even near the Earth\u2019s poles.<\/p>\n\n\n\n<p>The study also showed that under RCP8.5, \u201cnovel\u201d climates\nemerge across nearly 9 percent of Earth\u2019s land areas. These are conditions that\ndo not have geologic or historical precedent among the time periods studied,\nand concentrate in eastern and southeastern Asia, northern Australia and the\ncoastal Americas.<\/p>\n\n\n\n<p><em>Implications\nof this paper:<\/em> These findings make even more evident the SR1.5 conclusion\nthat emissions must peak and begin following lower-emissions pathways from\ncurrent levels within the next 12 years, by 2030; and show the climate changing\nmuch more abruptly than previously thought.&nbsp;\nNote that the Pliocene saw levels 20+ meters SLR above those of today. &nbsp;\u201cStabilization\u201d even at RCP4.5 levels will\ntherefore pose severe challenges to humanity\u2019s ability to adapt without\nwidespread disruption and migration\/managed retreat.<\/p>","protected":false},"excerpt":{"rendered":"<p>PNAS December 10: Models Show Abrupt Transition of Climate to Past Geologic States Main Messages: Already in 2030, Earth\u2019s climate will approach that of the mid-Pliocene (-3 million years) if current emissions levels continue unabated, eg RCP8.5 through 2030. Pliocene (&#8211;3 million), temps 2.8\u00b0-4.6\u00b0 above pre-industrial, with 20+ m. SLR If emissions continue on an [&#8230;]\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_lmt_disableupdate":"","_lmt_disable":"","footnotes":""},"categories":[152,9],"tags":[],"class_list":["post-1420","post","type-post","status-publish","format-standard","hentry","category-cryosphere-capsules","category-latest-research"],"modified_by":"Pam Pearson","_links":{"self":[{"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/posts\/1420","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/comments?post=1420"}],"version-history":[{"count":1,"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/posts\/1420\/revisions"}],"predecessor-version":[{"id":1421,"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/posts\/1420\/revisions\/1421"}],"wp:attachment":[{"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/media?parent=1420"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/categories?post=1420"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/iccinet.org\/zh\/wp-json\/wp\/v2\/tags?post=1420"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}