World climate leaders are meeting this week in Vienna for the next stage of international discussions about a global phase-down of climate-damaging hydrofluorocarbons (HFCs).

This meeting should lay the foundation for a 2016 amendment to the Montreal Protocol – a hugely successful global agreement that has put Earth’s fragile ozone layer on track to full restoration. A 2016 amendment would leverage the same proven mechanisms that helped fix the “ozone hole” to address another serious risk to the planet – HFCs.

When scientists discovered the “ozone hole” in the 1980s, they uncovered a tangible health risk to people and the environment. The ozone layer of our upper atmosphere is a natural sunscreen that protects us from harmful ultraviolet rays. A massive and growing “hole” in the ozone layer threatened to drive up skin cancer rates, harm marine life, ruin crops and even degrade wood, plastic and other construction materials.

The 1987 Montreal Protocol mandated that countries phase out ozone-depleting chlorofluorocarbons (CFC) and similar chemicals used widely at the time for air conditioning and refrigeration. With 197 countries signing on, it was the first UN treaty to achieve universal ratification in the United Nations.

The results have been remarkable. The peak ozone hole has shrunk dramatically by more than four million square kilometers (about the size of India), with a full recovery expected by mid-century. And despite fears of economic disruption, the private sector adjusted cost-effectively.

However, to phase out CFCs, countries needed viable alternatives. As ozone-depleting chemicals were phased out, many sectors began moving toward hydrofluorocarbons (HFCs) – chemicals that performed well as refrigerants and were significantly healthier for the ozone layer. But like the chemicals they replaced, HFCs are still damaging to our climate system. In fact, they are hundreds to thousands of times more powerful in warming the planet than carbon dioxide. Rapid growth in the use of HFCs threatens to undo much of our progress in reducing other carbon emissions under the Paris Climate Agreement.

It is time to amend the Montreal Protocol and phase down the use of HFCs in air conditioning and refrigeration – an urgent priority given the explosive actual and projected growth of air conditioning and refrigeration worldwide.

If we succeed, we could avoid up to 0.5 degree centigrade of warming by the end of the century by shifting towards other, less harmful alternatives. Avoiding that half-degree is crucial for limiting global temperature rise to below 2 degrees centigrade and avoiding the most severe impacts of climate change.

Last November in Dubai, negotiators agreed on a path forward to phase down HFCs by amending the Montreal Protocol in 2016. The amendment would mandate countries to replace HFCs, in stages, with climate-friendly alternatives such as hydrofluoroolefins (HFOs) and hydrocarbons.

We have the technologies and chemicals to get this done, and are confident we can produce an HFC amendment that works.

U.S. leaders will take the results of a newly-published Department of Energy report, The Future of Air Conditioning for Buildings, to Vienna. It documents air conditioning’s explosive growth worldwide, especially in developing nations, which could lead to huge increases in the use of HFCs and emissions of greenhouse gases. The report finds that air conditioning energy consumption in countries not part of the Organization for Economic Cooperation and Development (OECD) could rise 4-1/2 times 2010 levels by 2050 – emitting more HFC greenhouse gases and undercutting the Paris Agreement. Substitute chemicals are available to avoid the use of HFCs and their global warming impacts.

Here are some key findings:

• For air conditioning equipment categories that account for 95 percent of global residential sales and 35 percent of global commercial sales, climate-friendly refrigerants on the market have demonstrated comparable or superior performance and energy efficiency.
• Also, climate-friendly refrigerants are already being developed and commercialized in all other major air conditioning equipment categories.
• The air conditioning industry has steadily improved the energy efficiency of air conditioning units over time, including during the transition out of CFCs and other ozone-depleting substances into HFCs.
• Given that energy costs account for the majority of lifecycle air conditioning costs, energy efficiency improvements can more than offset increases in upfront purchase costs to consumers that could result from switching to HFC alternatives.

In short, the report demonstrates that the world is making rapid progress innovating toward a world without HFCs. In the near-term we can expect a wide array of air conditioning options that are climate-friendly, energy-efficient and affordable.

And also today, California is announcing that it will contribute half a million dollars toward a nearly $6 million effort launched last June to conduct critical research regarding the safe use of mildly flammable and flammable alternatives to HFCs. The U.S. made this announcement as part of the launch of the Clean Energy Ministerial’s Advanced Cooling Challenge, in order to accelerate updated safety standards to allow widespread use of these climate-friendly refrigerants in the United States and internationally.

As a part of the Challenge, DOE is working with the Air Conditioning, Heating, and Refrigeration Institute (AHRI) and the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) to support the acceleration of updated safety standards to allow widespread use of climate-friendly refrigerants in the United States and internationally. In support of the Advanced Cooling Challenge, the DOE is contributing $3 million in funding, AHRI is contributing $1 million, and ASHRAE is contributing $1.2 million.

It’s time for the world to come together to address HFCs. And this week’s negotiations are an important step down that path.