{"id":64,"date":"2004-12-08T18:44:21","date_gmt":"2004-12-08T22:44:21","guid":{"rendered":"\/?p=64"},"modified":"2005-04-21T22:59:12","modified_gmt":"2005-04-22T02:59:12","slug":"werent-temperatures-warmer-during-the-medieval-warm-period-than-they-are-today","status":"publish","type":"post","link":"https:\/\/www.realclimate.org\/index.php\/archives\/2004\/12\/werent-temperatures-warmer-during-the-medieval-warm-period-than-they-are-today\/","title":{"rendered":"Weren’t temperatures warmer than today during the “Medieval Warm Period”? Ne faisait-il pas plus chaud au Moyen-Age, pendant \u201cl\u2019Optimum climatique\u201d, que maintenant?<\/lang_fr>"},"content":{"rendered":"
\n

This is one of a number of popular myths regarding temperature variations in past centuries. At hemispheric or global scales, surface temperatures are believed to have followed the “Hockey Stick” pattern<\/a>, characterized by a long-term cooling trend from the so-called “Medieval Warm Period” <\/a> (broadly speaking, the 10th-mid 14th centuries) through the “Little Ice Age”<\/a> (broadly speaking, the mid 15th-19th centuries), followed by a rapid warming during the 20th century that culminates in anomalous late 20th century warmth. The late 20th century warmth, at hemispheric or global scales, appears, from a number of recent peer-reviewed studies, to exceed the peak warmth of the “Medieval Warm Period”. Claims that global average temperatures during Medieval times were warmer than present-day are based on a number of false premises<\/a> that a) confuse past evidence of drought\/precipitation with temperature evidence, b) fail to disinguish regional from global-scale temperature variations, and c) use the entire “20th century” to describe “modern” conditions , fail to differentiate between relatively cool early 20th century conditions and the anomalously warm late 20th century conditions.
\n
\npar Michael Mann (traduit par Thibault de Garidel)<\/small>
\nC’est un des nombreux mythes populaires concernant les variations de température sur les siècles passés. A l’échelle globale ou hémispherique, il est admis que les températures de surface ont suivi une évolution en forme de “crosse de hockey” – (“hockey stick”)<\/a>, caractérisée par une longue tendance au refroidissement depuis “l’Optimum Climatique Médiéval”<\/a> (grosso modo, du Xie au milieu du XIVie siècle) jusqu’au “Petit Age Glaciaire”<\/a> (grosso modo du milieu du XVie au XIXie siècle), suivie d’un réchauffement rapide au XXie siècle qui culmine par les températures anormalement élevées de la fin du XXie siècle. Ces températures élevées de la fin du XXie siècle, aux échelles hémisphérique ou globale, apparaissent, d’après de nombreux travaux récents évalués par des pairs, supérieures à celles maximales de l’Optimum Médiéval.
\n Les assertions de températures moyennes globales plus élevées au Moyen Age que maintenant sont fondées sur un certain nombre de prémisses fausses<\/a> qui (a) confondent les indicateurs de sécheresse\/précipitation avec ceux de température, (b) ne font pas la différence entre des variations globales et régionales de température, et (c) utilisent tout le 20ie siecle pour définir les conditions ‘modernes’, ce qui empêche de différencier les conditions relativement fraiches du début du 20ie et celles anormalement chaudes de la fin du 20ie.
\n<\/lang_fr><\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

This is one of a number of popular myths regarding temperature variations in past centuries. At hemispheric or global scales, surface temperatures are believed to have followed the “Hockey Stick” pattern, characterized by a long-term cooling trend from the so-called “Medieval Warm Period” (broadly speaking, the 10th-mid 14th centuries) through the “Little Ice Age” (broadly […]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[1,13,2],"tags":[],"class_list":{"0":"post-64","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-climate-science","7":"category-faq","8":"category-paleoclimate","9":"entry"},"aioseo_notices":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/64","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/comments?post=64"}],"version-history":[{"count":0,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/64\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/media?parent=64"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/categories?post=64"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/tags?post=64"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}