{"id":3771,"date":"2006-12-11T10:31:10","date_gmt":"2006-12-11T08:31:10","guid":{"rendered":"http:\/\/www.laterredufutur.com\/accueil1\/?p=3771"},"modified":"2026-06-08T06:14:29","modified_gmt":"2026-06-08T06:14:29","slug":"lamerique-du-nord-et-la-dna","status":"publish","type":"post","link":"https:\/\/www.laterredufutur.com\/accueil\/lamerique-du-nord-et-la-dna\/","title":{"rendered":"L&rsquo;Am\u00e9rique du Nord et la DNA"},"content":{"rendered":"<div class=\"1665f18d14f35dd9e7566e1a8ac9a3e9\" data-index=\"1\" style=\"float: none; margin:10px 0 10px 0; text-align:center;\">\n<script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"><\/script>\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:block; text-align:center;\"\r\n     data-ad-layout=\"in-article\"\r\n     data-ad-format=\"fluid\"\r\n     data-ad-client=\"ca-pub-2860849627502538\"\r\n     data-ad-slot=\"3019501113\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script>\n<\/div>\n<p align=\"justify\"><span style=\"font-size: small;\">Le r\u00e9chauffement plan\u00e9taire risquerait-il d\u2019engendrer paradoxalement un refroidissement du continent est-am\u00e9ricain?<\/span><\/p>\n<p align=\"justify\"><span style=\"font-size: small;\">Un sc\u00e9nario possible, s\u2019il en perturbait l\u2019actuelle boucle oc\u00e9anique dans l\u2019oc\u00e9an atlantique, celle du Gulf Stream et de la D\u00e9rive Nord-Atlantique (DNA).<\/span><\/p>\n<p align=\"justify\"><span style=\"font-size: small;\">Une dynamique relativement jeune \u2013 elle n\u2019a que 7000 ans \u2013 et bien fragile. C\u2019est ce que r\u00e9v\u00e8lent les travaux de recherches d\u2019Anne de Vernal et de Claude Hillaire-Marcel, professeurs au D\u00e9partement des sciences de la Terre et de l\u2019atmosph\u00e8re et chercheurs au G\u00c9OTOP-UQAM-McGill publi\u00e9s notamment dans Nature, que Qu\u00e9bec Science retenait parmi les 10 d\u00e9couvertes de l\u2019ann\u00e9e dans son dernier num\u00e9ro (f\u00e9vrier 2003).<\/span><\/p>\n<p align=\"justify\"><span style=\"font-size: small;\">\u00ab Le Gulf Stream et la d\u00e9rive nord-atlantique sont des courants chauds qui se d\u00e9placent \u00e0 la surface des oc\u00e9ans. Ces eaux ont une tr\u00e8s faible densit\u00e9, mais en circulant vers le Nord, leur temp\u00e9rature baisse et leur salinit\u00e9 augmente. De ce fait, elles deviennent tr\u00e8s denses et plongent dans les profondeurs, pour retourner ensuite vers le Sud. Cette \u2018plong\u00e9e\u2019, appel\u00e9e convection verticale, se produit \u00e0 deux endroits : au Nord de l\u2019Islande et dans la mer du Labrador. \u00bb<\/span><\/p>\n<p align=\"justify\"><span style=\"font-size: small;\">Depuis 1990, ces professeurs \u00e9tudient les courants marins dans le pass\u00e9, par l\u2019analyse des s\u00e9diments d\u00e9pos\u00e9s au fond de l\u2019oc\u00e9an depuis les 130 000 derni\u00e8res ann\u00e9es. Un long et fastidieux travail qui leur a permis de d\u00e9terminer la densit\u00e9 de l\u2019eau \u00e0 chaque p\u00e9riode : celle de la p\u00e9riode interglaciaire dite \u00ab chaude \u00bb, celle de l\u2019\u00e8re de la glaciation qui a suivi et celle de notre p\u00e9riode interglaciaire. Ils ont ainsi d\u00e9couvert qu\u2019il n\u2019y avait pas de convection verticale dans la derni\u00e8re p\u00e9riode interglaciaire, alors que la temp\u00e9rature moyenne de cette p\u00e9riode \u00e9tait sup\u00e9rieure de 2 degr\u00e9s Celsius \u00e0 celle d\u2019aujourd\u2019hui.<\/span><\/p>\n<p align=\"justify\"><span style=\"font-size: small;\">Ces deux degr\u00e9s suppl\u00e9mentaires auraient fait fondre la banquise, occasionnant un surplus d\u2019eau douce dans l\u2019Atlantique. \u00c9tant moins salines, donc moins denses, ces eaux de surface auraient alors cess\u00e9 de s\u2019enfoncer. Cette reconstitution du pass\u00e9 serait-elle un mod\u00e8le du futur climat de la plan\u00e8te? Aux mod\u00e9lisateurs du climat d\u2019y voir!<\/span><\/p>\n<p align=\"justify\">source : <a href=\"https:\/\/sciences.uqam.ca\/\">http:\/\/sciences.uqam.ca\/<\/a><\/p>\n<p class=\"bawpvc-ajax-counter\" data-id=\"3771\">(155)<\/p>\n<!--CusAds0-->\n<div style=\"font-size: 0px; height: 0px; line-height: 0px; margin: 0; padding: 0; clear: both;\"><\/div>","protected":false},"excerpt":{"rendered":"<p>Le r\u00e9chauffement plan\u00e9taire risquerait-il d\u2019engendrer paradoxalement un refroidissement du continent est-am\u00e9ricain? Un sc\u00e9nario possible, s\u2019il en perturbait l\u2019actuelle boucle oc\u00e9anique&#8230;<\/p>\n","protected":false},"author":1,"featured_media":3772,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"ngg_post_thumbnail":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[23],"tags":[395,1905,1030,241,169,170],"class_list":["post-3771","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-circulation-oceanique","tag-atlantique-nord","tag-dna","tag-eau-douce","tag-ocean","tag-rechauffement-climatique","tag-refroidissement-climatique","wpcat-23-id"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/North_America_satellite_globe.jpeg?fit=250%2C291&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p631RN-YP","jetpack-related-posts":[{"id":3942,"url":"https:\/\/www.laterredufutur.com\/accueil\/dossier-n3-les-courants-marins\/","url_meta":{"origin":3771,"position":0},"title":"Dossier N\u00b03 : Les Courants Marins","author":"Admin","date":"10 avril 2007","format":false,"excerpt":"Voici un dossier, en\u00a04 parties qui seront publi\u00e9es sur la Terre du Futur, transmis par Fifi321fth (Thomas),pass\u00e9 au lyc\u00e9e Sacr\u00e9-Coeur \u00e0 Reims. Thomas L., Enguerran D., Juliette M. Dossier Exclusif sur les Courants Marins et de ce qui en r\u00e9sulte. Ici 3 eme partie. Des mesures satellitaires ont r\u00e9v\u00e9l\u00e9 l'existence\u2026","rel":"","context":"Dans &quot;Climat&quot;","block_context":{"text":"Climat","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/climat\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/laterredufutur.com\/spaw\/images\/courant15.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/laterredufutur.com\/spaw\/images\/courant15.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/laterredufutur.com\/spaw\/images\/courant15.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":4097,"url":"https:\/\/www.laterredufutur.com\/accueil\/le-rechauffement-global-a-modifie-la-salinite-du-gs\/","url_meta":{"origin":3771,"position":1},"title":"Le r\u00e9chauffement global a modifi\u00e9 la salinit\u00e9 du GS","author":"Admin","date":"24 ao\u00fbt 2007","format":false,"excerpt":"Pour la plupart des personnes, le ralentissement ou m\u00eame l'arr\u00eat du\u00a0Gulf Stream\u00a0ne peut \u00eatre qu'une affaire de Science Fiction.\u00a0Ce vaste courant oc\u00e9anique sur la surface de l'Oc\u00e9an atlantique, qui fonctionne de la zone intertropicale vers les rivages de l'Europe (de ce fait assurant nos hivers chauds et \u00e9t\u00e9s temp\u00e9r\u00e9s) ne\u2026","rel":"","context":"Dans &quot;Climat&quot;","block_context":{"text":"Climat","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/climat\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/gulfstream1.jpg?fit=500%2C431&ssl=1&resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3949,"url":"https:\/\/www.laterredufutur.com\/accueil\/dossier-n4-les-courants-marins\/","url_meta":{"origin":3771,"position":2},"title":"Dossier N\u00b04 : Les Courants Marins","author":"Admin","date":"15 avril 2007","format":false,"excerpt":"Voici un dossier, en\u00a04 parties qui seront publi\u00e9es sur la Terre du Futur, transmis par Fifi321fth (Thomas), pass\u00e9 au lyc\u00e9e Sacr\u00e9-Coeur \u00e0 Reims. Thomas L., Enguerran D., Juliette M. Dossier Exclusif sur les Courants Marins et de ce qui en r\u00e9sulte. Ici\u00a04 eme partie... Sch\u00e9mas de la salinit\u00e9 de diff\u00e9rents\u2026","rel":"","context":"Dans &quot;Climat&quot;","block_context":{"text":"Climat","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/climat\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/laterredufutur.com\/spaw\/images\/courant19.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/laterredufutur.com\/spaw\/images\/courant19.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/laterredufutur.com\/spaw\/images\/courant19.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":27772,"url":"https:\/\/www.laterredufutur.com\/accueil\/comment-un-changement-du-gulf-stream-pourrait-signaler-leffondrement-dun-systeme-de-courant-oceanique-majeur\/","url_meta":{"origin":3771,"position":3},"title":"Comment un changement du Gulf Stream pourrait signaler l&rsquo;effondrement d&rsquo;un syst\u00e8me de courant oc\u00e9anique majeur","author":"Admin","date":"13 mars 2026","format":false,"excerpt":"Les variations du Gulf Stream, un puissant courant oc\u00e9anique de l'Atlantique, pourraient constituer un signal d'alarme pr\u00e9coce annon\u00e7ant l'effondrement imminent de la circulation m\u00e9ridienne de retournement atlantique (AMOC). L'AMOC est un vaste syst\u00e8me de courants oc\u00e9aniques qui agit comme un tapis roulant, transportant la chaleur des tropiques vers l'Atlantique Nord.\u2026","rel":"","context":"Dans &quot;Courants Marins&quot;","block_context":{"text":"Courants Marins","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/circulation-oceanique\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/gulfstream.jpg?fit=1200%2C747&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/gulfstream.jpg?fit=1200%2C747&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/gulfstream.jpg?fit=1200%2C747&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/gulfstream.jpg?fit=1200%2C747&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/gulfstream.jpg?fit=1200%2C747&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":3433,"url":"https:\/\/www.laterredufutur.com\/accueil\/le-gulf-stream\/","url_meta":{"origin":3771,"position":4},"title":"Le Gulf Stream","author":"Admin","date":"27 avril 2006","format":false,"excerpt":"Depuis plus d'un an, la Terre du Futur a essay\u00e9 de d\u00e9montrer que le Gulf Stream se portait tr\u00e8s mal. Apr\u00e8s des questions, des r\u00e9ponses ont \u00e9t\u00e9 apport\u00e9es. Voici la chronologie de cette recherche\u00a0sur le Gulf Stream\u00a0qui pourrait bien changer le climat du pourtour Atlantique. Ici les intervenants ont apport\u00e9\u00a0de\u2026","rel":"","context":"Dans &quot;Courants Marins&quot;","block_context":{"text":"Courants Marins","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/circulation-oceanique\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/spaw\/images\/gulfstream0505.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3542,"url":"https:\/\/www.laterredufutur.com\/accueil\/quand-la-nasa-apporte-son-rapport-sur-la-derive-nord-atlantique\/","url_meta":{"origin":3771,"position":5},"title":"Quand la Nasa apporte son rapport sur la D\u00e9rive Nord Atlantique","author":"Admin","date":"30 juin 2006","format":false,"excerpt":"Et voici un rapport qui pourrait \u00eatre nouveau et pourtant il date de 2004. 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