New modeling tool provides United Nations opportunity to meet environmental goals

December 9, 2025

A new open-source modeling tool co-developed by researchers at UC Berkeley’s Eric and Wendy Schmidt Center for Data Science & Environment provides global policymakers with unprecedented analytical and computational power to achieve environmental and climate goals.

Designed in partnership with the United Nations and numerous countries and supporting organizations, the tool, dubbed Kigali Sim, helps nations formulate policies to reduce overall greenhouse gas emissions—including hydrofluorocarbons (HFCs) commonly used in refrigeration, air conditioning, and the food system. Kigali Sim debuted on December 5 during the executive committee meeting of the Multilateral Fund for the Implementation of the Montreal Protocol.

“Kigali Sim improves global regulation of highly-potent greenhouse gases such as hydrofluorocarbons,” said lead developer Sam Pottinger, a senior research data scientist at Schmidt DSE (part of UC Berkeley's Rausser College of Natural Resources and the College of Computing, Data Science, and Society). “The tool simulates possible outcomes of policy interventions with greater efficiency and ease than previously possible. Kigali Sim is designed for those without programming expertise to access advanced modeling techniques, including optional AI features, and can work in a web browser.”

Using conservative estimates, Kigali Sim could help a hypothetical, middle-income nation formulate policies that could reduce overall greenhouse gas emissions by about 5% by 2040. For context, this would be the equivalent of the United States cutting half of all agriculture-related emissions.

The 5% estimated reduction would represent around 10% of that country’s target for emissions reductions under the Paris Agreement, given past commitments, long-term goals, and expected cooling pressures. These approximations do not account for additional co-benefits of reductions, including a country’s transition to more sustainable energy use, which will likely yield greater overall environmental benefits.

In order to achieve environmental goals set by the United Nations’ Montreal Protocol, policymakers need more powerful analytical tools to assess consumption trends and evaluate policy interventions. The Montreal Protocol, signed in 1987, is the most successful global environmental treaty in history and is ratified by all UN member states. Historically, the agreement sidestepped a potential catastrophe with the ozone layer by regulating ozone-depleting substances and greenhouse gases. Since 2016, the treaty’s focus is to phase down the most detrimental greenhouse gases like hydrofluorocarbons. To date the UN’s Multilateral Fund has facilitated more than $4.3 billion to support developing nations (also known as “Article 5” countries) in reducing production and consumption of HCFs and ozone-depleting substances.

Introducing Kigali Sim: an Open Source Tool to Help the United Nations Reach Environmental Goals

Sam Pottinger offers a walkthrough and demo of the Kigali Sim tool.

Schmidt DSE and the Multilateral Fund Secretariat designed Kigali Sim in partnership with officials from UN member countries and supporting organizations tasked with environmental policy decision-making. The tool provides an easy-to-use interface, where users can enter country-level modeling data to analyze HFC consumption trends. They can compare policies under consideration to quickly simulate potential impacts on emissions, consumption, and equipment across multiple scenarios.

Users can choose to bring in an AI assistant to more quickly process input data from various sources and formats, explore policy ideas with the computer as a partner, and rapidly analyze simulation results using simple language questions and answers.

“Kigali Sim offers an exciting opportunity to use cutting-edge data science tools 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 at the United Nations Environment Programme. “This tool provided a depth of policy analysis in under three hours that would have previously taken me three days to produce.”

“With this new resource, we can make greater strides to preserve our global environment,” added Tina Birmpili, chief officer of the Multilateral Fund. “It’s a compelling example of how we can bridge the innovation brought by university research centers like Schmidt DSE with international policy making."

During the beta testing phase earlier this year, delegates and other experts from more than 12 countries actively used Kigali Sim and provided critical feedback for improvements. This community represented Article 5 nations, donor countries (which financially contribute to the Multilateral Fund), international  nonprofits and agencies, and private consultants.

Kigali Sim is free and open source, and does not require previous coding experience. The tool can run locally in web browsers or on a desktop while allowing users to maintain privacy over their data. 

“Kigali Sim is incredibly unique in that it democratizes access to rigorous modeling techniques, and puts the latest in data science directly into the hands of decision-makers,” said Douglas McCauley, Schmidt DSE faculty director and an associate adjunct professor in the Department of Environmental Science, Policy, and Management. “Moreover, users with a variety of technical backgrounds can perform complex simulations and arrive quickly at results.”

Schmidt DSE leverages the power of modern data and environmental science to address pollution, the biodiversity extinction crisis, and other urgent climate change challenges. This is the third open source policy tool that the team has developed to date; others include a model that predicts the global production, use, and fate of plastics through 2050, and a tool to help depict future corn yields in the U.S. amidst a changing climate.

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A photo of six people standing and smiling under the UN logo in a conference room

DSE and UNEP Multilateral Fund Secretariat: From left: Federico Matteo San Martini, Magali de Bruyn, Sam Pottinger, Balaji Natarajan, Tina Birmpili, and Alejandro Ramirez-Pabon at the UN Open-ended Working Group meetings in Bangkok, July 2025. Photo courtesy of Schmidt DSE.