PartagerLes HFC contribuent à l'appauvrissement de la couche d'ozone, mais dans de faibles proportions (en anglais)
Bien que les HFC soient connus comme ayant un ODP nul, ils participent, dans de faibles proportions, à l'appauvrissement de la couche d'ozone, selon une nouvelle étude menée par la NASA. (en anglais)
Although HFCs are promoted as being zero ODP refrigerants, they do have a small but measurable effect on ozone depletion, according to a new study by NASA.
The new study, published in Geophysical Research Letters, the journal of the American Geophysical Union, focuses on five HFCs expected to contribute the most to global warming in 2050: R125, R143a, R134a, R32 and R23.
Atmospheric concentrations of HFCs are projected to increase considerably in the coming decades. Chemistry climate model simulations forced by current projections show that HFCs will impact the global atmosphere increasingly through 2050. As strong radiative forcers, HFCs increase tropospheric and stratospheric temperatures, thereby enhancing ozone-destroying catalytic cycles and modifying the atmospheric circulation.
According to NASA, HFCs will cause a 0.035% decrease in the ozone by 2050.
HFCs’ contribution to ozone depletion is small compared to its predecessors. For example, the once widely-used CFC R11, causes approximately 400 times more ozone depletion per unit mass than HFCs.
“We’re not suggesting HFCs are an existential threat to the ozone layer or to ozone hole recovery, but the impact isn’t zero as has been claimed,” said lead author Margaret Hurwitz, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “HFCs are, in fact, weak ozone-depleting substances.”
In the study, scientists also found that HFCs have a nearly linear impact on stratospheric temperature and ozone change. For example, reducing HFC emissions by 50% would decrease the ozone change by a comparable amount.
Geophysical Research Letters, Volume 42, Issue 20
28 October 2015
Pages 8686–8692
The new study, published in Geophysical Research Letters, the journal of the American Geophysical Union, focuses on five HFCs expected to contribute the most to global warming in 2050: R125, R143a, R134a, R32 and R23.
Atmospheric concentrations of HFCs are projected to increase considerably in the coming decades. Chemistry climate model simulations forced by current projections show that HFCs will impact the global atmosphere increasingly through 2050. As strong radiative forcers, HFCs increase tropospheric and stratospheric temperatures, thereby enhancing ozone-destroying catalytic cycles and modifying the atmospheric circulation.
According to NASA, HFCs will cause a 0.035% decrease in the ozone by 2050.
HFCs’ contribution to ozone depletion is small compared to its predecessors. For example, the once widely-used CFC R11, causes approximately 400 times more ozone depletion per unit mass than HFCs.
“We’re not suggesting HFCs are an existential threat to the ozone layer or to ozone hole recovery, but the impact isn’t zero as has been claimed,” said lead author Margaret Hurwitz, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “HFCs are, in fact, weak ozone-depleting substances.”
In the study, scientists also found that HFCs have a nearly linear impact on stratospheric temperature and ozone change. For example, reducing HFC emissions by 50% would decrease the ozone change by a comparable amount.
Geophysical Research Letters, Volume 42, Issue 20
28 October 2015
Pages 8686–8692