Three years ago, staff at the Multilateral Fund (MLF) posed a simple question: could a tool be built to help developing countries understand their HFC consumption trends and model the impact of the Montreal Protocol and its Kigali Amendment? A serendipitous encounter with scientists from UC Berkeley provided the answer and the beginning of a remarkable collaboration.
Published in the Journal of open-source software
In May 2026, the MLF was honoured to learn that the Kigali Sim had been published in the Journal of Open-Source Software (JOSS), a peer-reviewed academic journal recognizing research software of clear scientific and scholarly significance. Publication in JOSS is a mark of technical excellence and credibility. For a tool developed within a UN organization, it is a remarkable achievement.
The Kigali Sim is a free, open-source policy modelling tool born from the MLF’s deep expertise in supporting developing countries on HFC phase-down and the cutting-edge data science of the Eric and Wendy Schmidt Center for Data Science and Environment (DSE) at UC Berkeley. The published paper is available at: https://joss.theoj.org/papers/10.21105/joss.10104.
Presenting at UN Open-Source week 2026
Building on this milestone, the MLF Secretariat is honoured to present the Kigali Sim at UN Open-Source Week 2026, taking place 22–26 June at UN Headquarters in New York. The premier global forum for open-source collaboration in support of the Sustainable Development Goals and the Global Digital Compact, places the MLF at the heart of the UN’s vision for open and inclusive digital cooperation.
Kigali Sim delivers a depth of policy analysis in under three hours that would previously have taken three days. The MLF embodies the innovative spirit that UN Open-Source week celebrates.
Kigali Sim: making the grade
Launched at the 97th meeting of the Executive Committee in December 2025, the Kigali Sim provides analytical and computing power to help developing countries, researchers, and analysts understand HFC consumption trends and explore policy options under the Montreal Protocol’s Kigali Amendment. Its agentic AI feature, powered by Anthropic’s AI assistant Claude, enables users to build simulations, analyse data, and visualise results through natural conversation, without needing specialist technical skills. Data privacy is protected throughout: no sensitive information is transmitted to external servers.
The DSE has conservatively estimated that the Kigali Sim could help a hypothetical middle-income nation formulate policies that reduce direct emissions by around 5 per cent by 2040. A central challenge the tool addresses is the wide variation in technical capacity among nations implementing the Montreal Protocol and it was designed with accessibility at its core.
Since its launch, countries, policymakers, analysts, and non-profit organizations across more than a dozen nations have adopted the tool to simulate policy interventions and build evidence-based strategies for reducing HFC consumption.
Moving forward with passion, collaboration, and openness
The MLF Secretariat and DSE have been actively presenting Kigali Sim at international venues, including the Open-ended Working Group of the Parties to the Montreal Protocol, the Pacific Island Countries and South-East Ozone Officers Network raising awareness among implementing agencies and national ozone units around the world.
This collaboration was always driven by shared conviction: the DSE’s commitment to democratizing access to computational modelling tools, and the MLF’s passion for supporting developing countries in meeting their obligations under the 2016 Kigali Amendment efficiently and cost-effectively.
What began with a question and a chance encounter has grown into a peer-reviewed, internationally recognized tool used by countries and policymakers across the globe. The MLF looks forward to continuing this collaboration keeping Kigali Sim at the cutting edge and finding new ways to support Article 5 countries in meeting their environmental commitments.