Countries are gathering later this week in Kigali, Rwanda, to seal an agreement to freeze and phase down the super climate pollutants called hydrofluorocarbons (HFCs), found in air conditioners, refrigerators, and other uses. A strong HFC phase-down agreement would be another feather in the cap of the Montreal Protocol, the treaty that saved the ozone layer, and will be the biggest climate protection step countries can take in the year after the Paris Climate Agreement – which, by happy coincidence, just came into force today.

HFCs are the world's fastest growing climate pollutants. HFCs are powerful heat-trapping pollutants, packing hundreds to thousands of times the climate-warming punch of carbon dioxide, pound for pound. Phasing them down could help avoid 0.5°C more global warming by the turn of the century. If HFC growth is not stopped, it becomes virtually impossible to meet the Paris Agreement goals of holding warming below 2°C.

The last issues to be negotiated next week are the timing of the HFC freeze and phase-down for developed and developing countries, and the financial support that developed countries will make available to help developing nations act rapidly.

Timing really matters! Each year that an HFC freeze is delayed allows massive amounts of additional climate pollution – equivalent to billions of tons of carbon dioxide – to be produced, used, and eventually released into the atmosphere. To give a sense of the stakes next week in Kigali, we estimate the staggering environmental cost of delay based on the latest information: Depending on the length of the delay, the environmental cost of a slow start on freezing and phasing down HFCs ranges from 1 to 4 billion tons per year of CO2-equivalent.

Environmental Costs of Delaying the Freeze Year in Developing Countries (billion tons CO 2 -eq thru 2050) Freeze Year 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 Environmental Cost 0 1.3 2.8 4.6 7.3 9.9 11.9 14 16.4 20.2 23.6

Fast action is important because the environmental damage compounds with delay. By the time we reach 2025, each year of delay causes more than 2.5 billion more tons of CO2-equivalent pollution. By 2030, delay pushes the annual excess pollution well past 3 billion tons.

The overall difference between a freeze and phase-down starting in 2021 (supported by more than 100 developed and developing countries) versus starting in 2031 (India’s proposal) is nearly 24 billion tons of CO 2 -equivalent – the equivalent of all the CO 2 from 700 coal-fired power plants in 10 years, or the equivalent of the entire world’s climate pollution for 8 months.

An early HFC freeze and phase-down is possibly the easiest way to cut climate pollution. It will pay a double climate dividend, because more efficient air conditioners will cut power needs and pollution from developing countries’ over-stressed electric grids.

HFCs are the low-hanging fruit of climate change. They are extremely potent, they pack an immediate climate punch, and they are cheaper to limit than other climate pollutants such as CO 2 . In fact, the cost-per-ton of CO2-equivalent reductions ranges from $0.05 - $0.07 per ton (for an early start under the North American proposal) to $0.36 - $0.54 per ton (for a delayed start under the Indian proposal), according to the Montreal Protocol’s technical and economic panel.

That’s right: delay makes things more expensive, not cheaper. Countries will miss a huge opportunity if they don’t freeze and phase down HFCs ASAP.

The NRDC team will be in Kigali from Friday through next week. We’ll post regular updates on progress.

This post co-authored by Alex Hillbrand