{"id":45,"date":"2014-05-27T14:26:23","date_gmt":"2014-05-27T14:26:23","guid":{"rendered":"http:\/\/blog.ldeo.columbia.edu\/2014report\/?page_id=45"},"modified":"2015-02-10T20:42:10","modified_gmt":"2015-02-10T20:42:10","slug":"africanclimateandlife","status":"publish","type":"page","link":"https:\/\/blog.ldeo.columbia.edu\/2014report\/research\/africanclimateandlife\/","title":{"rendered":"African Climate and Life"},"content":{"rendered":"<p><strong>When the Sahara Turned to Sand <\/strong><\/p>\n<p>The Sahara wasn\u2019t always a desert. Trees and grasslands dominated the landscape from approximately 10,000 years ago to 5,000 years ago. Then, abruptly, the climate changed, and North Africa began to dry out.<\/p>\n<p>Previous research has suggested that the end of the African Humid Period came gradually, over thousands of years, but research recently published in Science by former Lamont postdoctoral researcher Jessica Tierney (now at Woods Hole Oceanographic Institution) and Lamont climate scientist Peter deMenocal says it took just a few hundred. The shift was initially triggered by more sunlight falling on Earth\u2019s northern hemisphere, as Earth\u2019s cyclic orientation toward the sun changed. But how that orbital change caused North Africa to dry out so fast \u2013 in 100 to 200 years, the scientists say \u2013 is a matter of debate.<\/p>\n<p><iframe loading=\"lazy\" src=\"\/\/player.vimeo.com\/video\/76960917\" width=\"770\" height=\"433\" frameborder=\"0\" title=\"Researching Ancient Climate Change, Peter deMenocal Faced Threat of Pirates\" webkitallowfullscreen mozallowfullscreen allowfullscreen><\/iframe><\/p>\n<p>Two feedback mechanisms have been proposed. In the first, as the climate becomes warmer and drier, trees give way to sparser vegetation, making the now barren region warmer and drier, causing more vegetation to wither. The explanation favored by the authors is that shifting sea-surface temperatures in the Indian Ocean reduced rainfall over east Africa.<\/p>\n<p>Their research puts the dawn of the Egyptian state, at about 5,000 years ago, into context and suggests that feedback mechanisms could cause similar rainfall switches in North Africa and other regions as humans continue to heat the planet. \u201cIt\u2019s evidence that climate doesn\u2019t respond gradually to gradual forcing,\u201d deMenocal told The Atlantic.<\/p>\n<p>The study is also one of the few climate reconstructions to have come out of the region recently. One of the crucial sediment cores was recovered in 2001 aboard a Dutch research ship in the Gulf of Aden a couple of months before the September 11 terrorist attacks, just before a major surge of terrorism, political unrest and piracy largely placed the Horn of Africa off-limits to scientists.<\/p>\n<p>Even then, pirates were already a danger, deMenocal explains in the video above. Lamont\u2019s own research ship, the R\/V <em>Maurice Ewing<\/em>, had been attacked with rocket-propelled grenades a few months before. To avoid detection, the captain shut off the ship\u2019s radar, radio and navigation lights as they sailed along the coasts of Somalia and Yemen. By fax, the ship received updates of known pirate attacks, some near sites they had planned to core. But they got their core and eventually docked safely in Egypt.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>When the Sahara Turned to Sand The Sahara wasn\u2019t always a desert. Trees and grasslands dominated the landscape from approximately 10,000 years ago to 5,000 years ago. Then, abruptly, the climate changed, and North Africa began to dry out. Previous research has suggested that the end of the African Humid Period came gradually, over thousands [&hellip;]<\/p>\n","protected":false},"author":17,"featured_media":0,"parent":24,"menu_order":60,"comment_status":"closed","ping_status":"closed","template":"","meta":{"__cvm_playback_settings":[],"__cvm_video_id":""},"_links":{"self":[{"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/pages\/45"}],"collection":[{"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/comments?post=45"}],"version-history":[{"count":27,"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/pages\/45\/revisions"}],"predecessor-version":[{"id":404,"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/pages\/45\/revisions\/404"}],"up":[{"embeddable":true,"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/pages\/24"}],"wp:attachment":[{"href":"https:\/\/blog.ldeo.columbia.edu\/2014report\/wp-json\/wp\/v2\/media?parent=45"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}