Commitments to reach net-zero emissions by 2050, andkeep temperature rise below 1.5C, will only reduce, notstop the impacts of climate change. We must adapt now.Information is needed on where, and who, will be affectedand what should be done. The Intergovernmental Panel onClimate Change (IPCC) has sought to do this via itsAssessment Reports. Thirty years since the first report,progress on adaptation remains slow. It is unclear why some national policymakers fail toimplement effective adaptation policies whilst others adoptambitious ones. Inaction is often due to information failingto give decision-makers what they need. To resolve this,the IPCC increasingly involves scientists and policymakersto co-produce its climate science to improve the usabilityand use of that science. But there is a lack of data on theeffectiveness or how the IPCC reports are used to informadaptation decisions. Through an analysis of officialdocuments and expert interviews, this research will givescholars, practitioners, and policymakers crucial insightsinto how to accelerate adaptation action.Uniting cross-disciplinary findings, this project aims to: - Understand how the IPCC's communication of scienceshapes its use in national adaptation policies and decision-making- Examine how, and why, national adaptation policiesdevelop differently across countries- Test the role played by co-production in improving theusability and use of climate science in adaptationpolicymaking.