Kigali Sim Achieves Peer-Reviewed Publication, Advancing Open Source Environmental Research
In collaboration with the Secretariat of the Multilateral Fund for the Implementation of the Montreal Protocol (MLF), today DSE announced publication of Kigali Sim in the Journal of Open Source Software. The milestone marks a new chapter for the free, open-source modeling tool that helps policymakers worldwide assess strategies to reduce emissions from hydrofluorocarbons (HFCs), which are some of the most potent greenhouse gases, under the Montreal Protocol’s Kigali Amendment. The paper is co-authored by DSE and MLF.
“This publication validates Kigali Sim’s technical foundation and makes it easier for other researchers and analysts to build on our work,” said Sam Pottinger, lead author and Kigali Sim developer at DSE. “Our goal with Kigali Sim was to democratize access to the kind of computational modeling available in the tool, which was previously only available through proprietary or ad-hoc tools.”
Using conservative estimates, Kigali Sim could help a hypothetical, middle-income nation formulate policies that could reduce use of potent greenhouse gases. These steps could decrease this nation's direct emissions by about 5% by 2040.
Since the tool’s initial launch in December 2025, Kigali Sim’s reach has expanded substantially. More than a dozen nations and supporting organizations—represented by policymakers, analysts, and nonprofit leaders—are using the tool to simulate possible outcomes of policy interventions with greater efficiency and ease than previously possible. Peer review of Kigali Sim by the scientific community affirms the rigor and transparency of the team’s development and design approach.
“Kigali Sim is a very unique and powerful tool that leverages cutting-edge data science, like AI, to guide funding implementation under the Montreal Protocol,” said Balaji Natarajan, Secretariat of the Multilateral Fund for the Implementation of the Montreal Protocol, United Nations Environment Programme. “It provided a depth of policy analysis in under three hours that would have previously taken me three days to produce.”
A central challenge the tool addresses is the wide variation in technical expertise among the nations and organizations working to implement the Montreal Protocol. Kigali Sim meets users where they are through a dual-interface design: a visual, no-code point-and-click editor for users new to modeling, and QubecTalk, a domain-specific language created by the team for users who prefer code-based workflows.
Recently, Schmidt DSE added new agentic AI features that allow AI assistants (i.e. Claude, Gemini, etc.) to take a more active role in building and refining simulations. Assistants can analyze data proactively for the user, as well as summarize and visualize output. The Kigali Sim application does not need to be open while the AI performs these tasks. Read more about our collaboration with the United Nations on Kigali Sim.
“Kigali Sim runs via web browser on a user’s own machine, which avoids transmitting sensitive information to external servers and preserves data privacy,” said Magali de Bruyn, coauthor and Data Scientist / Research Software Engineer DSE. “We know this is particularly important for Article 5 nations, which may operate with limited resources and handle proprietary national data.”
The team has presented Kigali Sim at numerous international venues, including meetings of the Executive Committee of the Multilateral Fund, the Pacific Island Countries Ozone Officers Network, and the South East Asia and the Pacific Ozone Officers Network. The tool received media coverage from NBC Bay Area, which spotlighted UC Berkeley’s contributions to UN environmental efforts.
Background on the Montreal Protocol
The Montreal Protocol, ratified by all UN member states, has phased out 99% of ozone-depleting substances and stands as history’s most successful international environmental treaty. Its 2016 Kigali Amendment extended that framework to HFCs, or some of the world’s most potent greenhouse gases. The Multilateral Fund has distributed over $4.3 billion to support developing nations in this transition.
