My research explores how societies can transform towards more sustainable futures, and crosses many disciplinary boundaries, connecting Earth system sciences to the study of societal change and policy. I publish on the effectiveness of international climate policy including the Paris Agreement, carbon budgets, the urgency of climate mitigation action, global net zero emission targets, the interaction between climate and sustainable development, emission pathways that limit global warming to 1.5°C and 2°C, and climate justice.
Over the past decade, I've contributed and led several scientific assessments that informed the UN climate negotiations. I've been a lead author on the annual Emissions Gap Reports by the United Nations Environment Programme (UNEP) since 2010. I was a Contributing Author to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), served as a Coordinating Lead Author on mitigation pathways for the IPCC Special Report on 1.5°C of Global Warming, and am currently a Lead Author for the IPCC’s Sixth Assessment.