15307146_mUSA: 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.

According to NASA, HFC emissions cause increased warming of the stratosphere, speeding up the chemical reactions that destroy ozone molecules, and they also decrease ozone levels in the tropics by accelerating the upward movement of ozone-poor air.  According to the model, their impact is such that HFCs will cause a 0.035% decrease in ozone by 2050.

HFCs’ contribution to ozone depletion is small compared to its predecessors. For example, the once widely-used CFC refrigerant R11, causes about 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. Such a direct relationship will prove useful for evaluating the impacts of emerging HFCs, Hurwitz said. “We can provide policy makers with an estimate of the stratospheric impacts of new HFC gases.”