Working Group III

Working Group III (WGIII) is one of three working groups of the Intergovernmental Panel on Climate Change (IPCC), the UN-mandated body that assesses the science of climate change. While Working Group I covers the physical science basis and Working Group II addresses impacts, adaptation, and vulnerability, WGIII focuses on the mitigation of climate change — that is, the human actions, policies, technologies, and economic pathways that can reduce greenhouse gas emissions or enhance sinks.

WGIII assessments evaluate options across sectors including energy supply, transport, buildings, industry, agriculture and land use (AFOLU), and urban systems. They also analyze cross-cutting issues such as carbon pricing, climate finance, technology transfer, sustainable development linkages, demand-side measures, and the costs and feasibility of emissions pathways consistent with temperature goals like those in the Paris Agreement.

Each IPCC assessment cycle produces a WGIII contribution to the broader Assessment Report. The most recent is the WGIII contribution to the Sixth Assessment Report (AR6), titled Climate Change 2022: Mitigation of Climate Change, approved in April 2022. Earlier contributions appeared in AR5 (2014), AR4 (2007), AR3 (2001), AR2 (1995), and the First Assessment Report (1990). WGIII also produces special reports jointly with other working groups, such as the Special Report on Global Warming of 1.5°C (2018) and the Special Report on Climate Change and Land (2019).

The group operates through a co-chair structure, with a Technical Support Unit hosted by a member government, and produces three layers of output: the full assessment chapters (drafted by hundreds of volunteer scientists), a Technical Summary, and a Summary for Policymakers (SPM) that is approved line-by-line by government delegations in plenary. This approval process gives WGIII findings unusual weight in UNFCCC negotiations, where they routinely inform NDC reviews, the Global Stocktake, and debates over mitigation ambition.

For MUN delegates and researchers, WGIII is the canonical source for emissions scenarios, sectoral mitigation potentials, and policy effectiveness assessments.