Hydrofluorocarbons (HFCs), known for protecting the ozone layer from destruction, may also be responsible for global warming, a recent research has held.
The research was conducted by scientists from NOAA's Earth System Research Laboratory and their colleagues.
HFCs, which do not contain ozone-destroying chlorine or bromine atoms, are used as substitutes for ozone-depleting compounds such as chlorofluorocarbons (CFCs) in such uses as refrigeration, air conditioning, and the production of insulating foams.
The researchers took a fresh look at how the global use of HFCs is expected to grow in coming decades.
Using updated usage estimates and looking farther ahead than past projections (to the year 2050), they found that HFCs, especially from developing countries, will become an increasingly larger factor in future climate warming.
"HFCs are good for protecting the ozone layer, but they are not climate friendly," said David W. Fahey, a scientist at NOAA and second author of the new study.
"Our research shows that their effect on climate could become significantly larger than we expected, if we continue along a business-as-usual path," he added.
HFCs currently have a climate change contribution that is small (less than 1 percent) in comparison to the contribution of carbon dioxide (CO2) emissions.
The researchers have shown that by 2050, the HFCs contribution could rise to 7 to 12 percent of what CO2 contributes, and if international efforts succeed in stabilizing CO2 emissions, the relative climate contribution from HFCs would increase further.
Though the HFCs do not deplete the ozone layer, they are potent greenhouse gases.
Molecule for molecule, all HFCs are more potent warming agents than CO2 and some are thousands of times more effective.
The new study factored in the expected growth in demand for air conditioning, refrigerants, and other technology in developed and developing countries.
The Montreal Protocol's gradual phasing out of the consumption of ozone-depleting substances in developing countries after 2012, along with the complete phase-out in developed countries in 2020, are other factors that will lead to increased usage of HFCs and other alternatives.
Decision-makers in Europe and the United States have begun to consider possible steps to limit the potential climate consequences of HFCs.
According to John S. Daniel, a NOAA coauthor of the study, "While unrestrained growth of HFC use could lead to significant climate implications by 2050, we have shown some examples of global limits that can effectively reduce the HFCs' impact."