The International Center for Climate Governance (ICCG) announces the publication of its 2015 “Climate Think Tank Ranking”, the authoritative and worldwide known assessment of the most cutting-edge institutions working in the field of climate change economics and policy. This fourth edition of ICCG’s Climate Think Tank Ranking assesses 240 non-University affiliated think tanks, specialized in the field of climate change economics and policy, figuring in the Think Tank Map observatory. In contrast to other think tank rankings, the ICCG ranking is based on a solid quantitative methodology and analytical data. Think tanks were assessed on a set of 15 indicators structured in three main pillars: Activities, Publications and Dissemination. As in the previous editions, two different rankings were built. The first is the Standardized Ranking, which measures the think tanks’ efficiency in per capita/researcher terms, while the Absolute Ranking measures the think tanks’ performance regardless of their size. The ICCG’s 2015 Climate Think Tank Award for the highest impact think tank working on climate change economics and policy is based on the standardized ranking.