April 14, 2014 - Concluding four years of intense scientific collaboration by hundreds of authors from around the world, this report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness. The quintessence of this work, the Summary for Policymakers, has been approved line by line by member governments at the 12th Session of IPCC WG III in Berlin, Germany (7-11 April 2014).