OSLO Greenhouse gases from chemicals used in refrigerants and air conditioning are set to be a bigger than expected spur of climate change by 2050, scientists said.
In the worst case, use of hydrofluorocarbons (HFCs) could surge to cause global warming in 2050 equivalent to the impact of between 28 and 45 percent of emissions of carbon dioxide, the main heat-trapping gas from burning fossil fuels, they said.
"HFCs present a significant threat to the world's efforts to stabilize climate emissions," Guus Velders, the lead author at the Netherlands Environmental Assessment Agency, said of the findings by a team of Dutch and U.S.-based scientists.
HFCs' current heat-trapping contribution to global warming is less than 1 percent of that of carbon dioxide. HFCs are used in air conditioning units, including in 80 percent of new cars, in refrigerants and in insulation foams.
HFCs were introduced before human-caused global warming was identified as a huge problem, to replace an older generation of chemicals that were damaging the ozone layer that shields the planet from harmful ultra-violet rays.
The United Nations Environment Programme (UNEP) said the study, in Tuesday's edition of the U.S. journal Proceedings of the National Academy of Sciences, showed there were easy ways to fight global warming alongside cuts in carbon emissions.
"There are other low-hanging fruit in the climate challenge," UNEP head Achim Steiner said in a statement on HFCs. He says climate change is set to cause worsening droughts, floods, heatwaves and rising sea levels.
"By some estimates, action to freeze and then reduce this group of gases could buy the world the equivalent of a decade's worth of carbon dioxide emissions," he said.
More than 190 nations plan to agree a new climate pact in Copenhagen in December to succeed the U.N.'s Kyoto Protocol, which regulates emissions of six greenhouse gases including carbon dioxide and HFCs.
"There are simple, market-ready solutions (to HFCs) waiting to be deployed provided adequate incentives are provided," said Kert Davies, U.S. research director for environmental group Greenpeace.
Greenpeace said companies such as Bosch-Siemens, Whirlpool, Panasonic, Samsung, Miele and Ben & Jerry's sold or were testing alternative "Greenfreeze" technologies.
The European Union plans to phase out HFCs in new air conditioning systems in cars in coming years. The study said that by 2050, developing nations might be emitting as much as 800 times more HFCs than developed nations.
It suggested the best way of curbing emissions from HFCs was a "global freeze followed by modest annual reductions" involving developed and developing nations.
"HFCs are good for protecting the ozone layer, but they are not climate-friendly," said David W. Fahey, a scientist at the U.S. National Oceanic and Atmospheric Administration who was among the authors.
(Editing by Robert Woodward)