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HFC greenhouse gases: a tale of two (or more) futures
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HFC greenhouse gases: a tale of two (or more) futures

New research projects greenhouse effect from substances that replaced ozone-depleting products

There’s good news and bad news about hydrofluorocarbons (HFCs), the gases that replaced the ozone-depleting substances that were used in refrigerators and air conditioners. 

First the good news: HFCs are indeed much less damaging to Earth’s protective ozone layer. The bad news is that many HFCs currently in use are strong greenhouse gases, and they have been increasing rapidly in the atmosphere.

A new paper appearing online in Atmospheric Environment  coauthored by researchers at NOAA’s Earth System Research Laboratory looked at the climate implications of various proposals for future HFC use that are being discussed this week under the United Nations Montreal Protocol, the global agreement that protects the ozone layer. 

The study shows that the HFC proposals lead to a range of possible futures. They range from HFCs contributing 10 percent as much as carbon dioxide to the greenhouse effect in 2050, if no new course is taken, to the HFC contribution declining to 2 percent as much as CO2 in 2050, if proposals set forth by North America, the Pacific Island states, and the European Union (EU) are adopted. The current contribution of HFCs is 1 percent.

The proposals are under discussion this week at the Montreal Protocol meeting in Dubai, where from November 1 to 5 some 197 countries are negotiating potential reductions in the use of HFCs that are most likely to exacerbate climate change.

David W. Fahey, a coauthor of the new study and director of the Chemical Sciences Division at NOAA’s Earth System Research Laboratory, is attending the meeting in Dubai. “By looking at the proposed HFC amendments in a scientific framework, our paper helps inform decisions facing the Montreal Protocol negotiators in Dubai,” Fahey said.

The research was led by Guus Velders of the National Institute for Public Health and the Environment in the Netherlands.  Coauthors are from NOAA in Boulder, Colorado, the Institute for Governance and Sustainable Development in Washington D.C., and the Chemours Company in Delaware.

Projections are for a large growth in demand for HFCs, and some countries, including the U.S., Japan, and EU, have already instituted measures to restrict their use.  However, these existing agreements will have a limited impact because future HFC use is expected to grow fastest in Asia, Latin America, the Middle East and Africa.

The Montreal Protocol proposals would reduce HFC emissions significantly, according to the new study.  Proposals submitted in 2015 by North American countries, the EU, India, and eight Pacific Island states would reduce HFC emissions from developed countries by 80 percent or more in 2050, compared to “business as usual.”  Developing-country emissions would be reduced by 50 percent under India’s proposal, and by 90 percent under other proposals.

The climate effects of HFCs would start to decline by 2035 for all of the proposals under discussion in Dubai, and by 2050 would have declined by anywhere from one-third to two-thirds compared to business as usual, depending on the proposal adopted. Without a new agreement, the effect of HFCs will continue to increase. Currently, the contribution of HFCs to greenhouse warming is 1 percent of that of CO2, and by 2050 that contribution would increase to 10 percent of that of CO2.

New compounds, such as hydrofluoro-olefins, have been developed for refrigeration and air conditioning applications, enabling national (U.S., Japan) and regional (EU) control measures.

“Alternatives to HFCs are increasingly available as technology advances,” said Fahey.  “We hope our study helps decision-makers by putting numbers on the different futures that are possible.”

For more information please contact Monica Allen, director of public affairs for NOAA Research, at 301-734-1123 or by email at

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Oceanic and Atmospheric Research (OAR) - or "NOAA Research" - provides the research foundation for understanding the complex systems that support our planet. Working in partnership with other organizational units of the NOAA, a bureau of the Department of Commerce, NOAA Research enables better forecasts, earlier warnings for natural disasters, and a greater understanding of the Earth. Our role is to provide unbiased science to better manage the environment, nationally, and globally.


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