CSD News & Events:

News & Events - 2015

HFC Greenhouse Gases: A Tale of Two (or more) Futures

2 November 2015
modified figure 5

Figure: modified from Velders et al., Atmospheric Environment, 2015

A new paper coauthored by NOAA scientists examined the climate implications of proposed amendments to the Montreal Protocol regarding emissions of hydrofluorocarbons (HFCs), which are used in refrigeration and air conditioning. Formal negotiations regarding the proposals are taking place at a Montreal Protocol meeting underway in Dubai 1-5 November 2015.

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.

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

A new paper coauthored by researchers in NOAA's Earth System Research Laboratory looked at the climate implications of various proposals for future HFC use that are currently being discussed under the United Nations Montreal Protocol, the global agreement that protects the ozone layer. The new study shows that the HFC proposals lead to a range of possible futures – from HFCs contributing 10 percent as much as carbon dioxide (CO2) to the greenhouse effect in 2050 if no new course is taken, to the HFCs' contribution declining to 2 percent as much as CO2 in 2050 if proposals such as the ones put forth by North America, the Pacific Island States, and the European Union (EU) are adopted.

The proposals are currently under discussion at the Montreal Protocol meeting in Dubai, where from November 1-5 a total of 197 countries are negotiating the possible reductions in the use of the particular HFCs that are the most harmful to climate.

David W. Fahey, a coauthor of the new study and director of the Chemical Sciences Division at NOAA's Earth System Research Laboratory, will see the action unfold in Dubai. "By looking at the proposed HFC amendments in a scientific framework, our paper helps inform the decisions facing the Montreal Protocol negotiators in Dubai," said Fahey.

The new paper, led by Guus Velders of the National Institute for Public Health and the Environment (RIVM) in the Netherlands, is published online in Atmospheric Environment. Coauthors of the paper are from NOAA in Boulder, Colorado, the Institute for Governance and Sustainable Development in Washington D.C., and 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 the growth in future HFC use is expected to be most acute 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 all reduce the HFC emissions from developed countries by 80 percent or more in 2050, compared to the "business as usual" baseline. 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 rise, from its current contribution of 1 percent of that of CO2, to a projected contribution in the year 2050 that is 10 percent of that of CO2.

New compounds, such as HFCs that are weak greenhouse gases, and hydrofluoroolefins (HFOs), have been developed for refrigeration and air conditioning applications, enabling the 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 the decision-makers by putting numbers on the different futures that are possible."

Citation: Guus J.M. Velders, David W. Fahey, John S. Daniel, Stephen O. Andersen, Mack McFarland, Future atmospheric abundances and climate forcings from scenarios of global and regional hydrofluorocarbon (HFCs) emissions, Atmospheric Environment, doi:10.1016/j.atmosenv.2015.10.071, 2015.


Hydrofluorocarbons (HFCs) are manufactured for use as substitutes for ozone-depletingsubstances that are being phased out globally under Montreal Protocol regulations. While HFCs do not deplete ozone, many are potent greenhouse gases that contribute to climate change. Here, new global scenarios show that baseline emissions of HFC could reach 4.0-5.3 GtCO2-eq yr-1 in 2050. The new baseline (or business-as-usual) scenarios are formulated for 10 HFC compounds, 11 geographic regions, and 13 use categories. The scenarios rely on detailed data reported by countries to the United Nations; projections of gross domestic product and population; and recent observations of HFC atmospheric abundances. In the baseline scenarios, by 2050 China (31%), India and the rest of Asia (23%), Middle East and northern Africa (11%), and USA (10%) are the principal source regions for global HFC emissions; and refrigeration (40-58%) and stationary air conditioning (21-40%) are the major use sectors. The corresponding radiative forcing could reach 0.22-0.25 W m-2 in 2050, which would be 12-24% of the increase from business-as-usual CO2 emissions from 2015 to 2050. National regulations to limit HFC use have already been adopted in the European Union, Japan and USA, and proposals have been submitted to amend the Montreal Protocol to substantially reduce growth in HFC use. Calculated baseline emissions are reduced by 90% in 2050 by implementing the North America Montreal Protocol amendment proposal. Global adoption of technologies required to meet national regulations would be sufficient to reduce 2050 baseline HFC consumption by more than 50% of that achieved with the North America proposal for most developed and developing countries.

More information:

RIVM Netherlands Press Release: Without measures emissions of HFC greenhouse gases will increase rapidly