International Visitor Lecture: Durwood Zaelke and Climate Tipping Points

The 2025–2026 International Law Visitor, Durwood Zaelke, shared his insights on global environmental agreements that protect the climate and avoid triggering a tipping point in the Earth’s temperature.

President of the Institute of Governance and Sustainable Development, Zaelke is a professor, author, and advocate, working for more than five decades to protect the planet.

“Durwood’s creativity, inspiration, and persistence is a reminder to all of us … to not be complacent, to remain hopeful, and to work diligently to protect the planet,” says professor Chris Wold, chair of the International Law Committee.

One of Zaelke’s most notable works has been facilitating climate pollutant reduction under the Montreal Protocol. Ratified by 198 countries, the Protocol phases out ozone-depleting substances like CFCs and HCFCs, preventing serious health impacts.

Zaelke successfully pushed for a faster HCFC phase-out in 2007 and spearheaded the Kigali Amendment to the Montreal Protocol, which targeted hydrofluorocarbons (HFCs). The agreement is projected to prevent up to 0.5°C of global warming by century’s end, potentially doubling with improved AC energy efficiency. Zaelke continues to tirelessly build on his lifetime of work, warning of impending climate tipping points. He emphasizes the urgent need to reduce short-lived climate super pollutants like methane to buy time for carbon dioxide emission reductions.