Does Hosting a COP Summit Drive Climate Mitigation?

UNFCCC Conference of the Parties (COP) have become the world’s largest and most important climate meetings. Since the first COP in 1995, host governments and incoming COP presidents have been expected to raise ambition and lead by example. In the run-up to summits, hosts often respond by announcing high-profile emissions targets or institutional reforms such as climate laws or the creation of climate ministries. Yet, it remains unclear whether these announcements translate into tangible outcomes, such as lower emissions. This paper empirically examines whether hosting a COP summit affects (i) national climate-policy adoption and (ii) GHG emissions, using a difference-in-differences design, drawing on a country-year data from 1995-2024. We compare host countries to countries that are similar in important aspects but did not host a climate summit within a five-year window and provide systematic evidence on whether COP hosting translates into measurable domestic mitigation outcomes.