Aggregating the Impacts of Non-State and Subnational Climate Actions: An Exploration of Methods

This research paper serves as a methodological supplement to the Initiative for Climate Action Transparency (ICAT) Non-State and Subnational Action (NSA) Guide. It explores the assumptions and decision points involved in estimating the collective ex-ante greenhouse gas (GHG) emissions impact of mitigation actions taken by cities, businesses, and states, with a focus on enhancing transparency and comparability of results.

• The paper addresses the challenge that variations in methodological assumptions and data availability make it difficult to communicate, interpret, and compare the results of individual assessments of non-state and subnational climate actions.
• Methodological decisions regarding the scope and conservativeness of an assessment significantly influence the outcome: a broad scope may show larger potential reductions but risk including unachievable actions, while high conservativeness may produce more realistic results but risk excluding ambitious actors who need support.
• To support the aggregation of ex-ante GHG emissions impacts, the Initiative for Climate Action Transparency (ICAT) provides the Non-State and Subnational Action (NSA) Guide for data collection and impact assessment, alongside an excel-based Climate Action Aggregation Tool (CAAT) released in 2021.
• The document emphasizes that because different studies may appear comparable while using different underlying assumptions, it is critical for researchers to transparently communicate these assumptions to ensure the credibility of results and to help understand how these actions support national governments in meeting or exceeding Nationally Determined Contributions (NDCs).

APA

World Resources Institute (n.d.). Aggregating the Impacts of Non-State and Subnational Climate Actions: An Exploration of Methods. https://www.wri.org/research/aggregating-impacts-non-state-and-subnational-climate-actions-exploration-methods

Chicago

World Resources Institute. Aggregating the Impacts of Non-State and Subnational Climate Actions: An Exploration of Methods. n.d. https://www.wri.org/research/aggregating-impacts-non-state-and-subnational-climate-actions-exploration-methods.

Wikipedia

{{cite report |author=World Resources Institute |title=Aggregating the Impacts of Non-State and Subnational Climate Actions: An Exploration of Methods |url=https://www.wri.org/research/aggregating-impacts-non-state-and-subnational-climate-actions-exploration-methods |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{worldresourcesinstitutendaggregating, author = {{World Resources Institute}}, title = {{Aggregating the Impacts of Non-State and Subnational Climate Actions: An Exploration of Methods}}, institution = {World Resources Institute}, url = {https://www.wri.org/research/aggregating-impacts-non-state-and-subnational-climate-actions-exploration-methods}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }