Widely Used Coolants Contribute to Ozone Depletion

Scientists take a closer look at chemicals once thought to be harmless to Earth s ozone layer. Find out more about HFCs and how they contribute to ozone depletion in this video. Atmospheric concentrations of HFCs are growing at 7 percent a year and are projected to be over 17 times higher by the year 2050. Using a NASA computer model, scientists simulated the impacts of HFCs on ozone levels into the future. This image shows the projected impacts of HFCs on ozone levels at the various latitudes in 2050.

Forecast stratospheric ozone depletion due to hydroflourocarbin emissions from 2000 to 2050.This video is also available on our YouTube channel. A class of widely used chemical coolants known as hydrofluorocarbons (HFC) contributes to ozone depletion by a small but measurable amount, countering a decades-old assumption, according to a new NASA study.The ozone layer comprises a belt of ozone molecules located primarily in the lower stratosphere. It is responsible for absorbing most of the sun’s harmful ultraviolet radiation before it reaches Earth’s surface. Research in the 1990s showed that HFCs, which have replaced more powerful ozone-depleting chemical coolants in recent years, destroy a negligible amount of ozone. But that conclusion was reached by examining only the gases’ ability to break down ozone molecules through chemical reactions that take place following the breakdown of these molecules in the atmosphere.The new study, which focused on the five types of HFCs expected to contribute the most to global warming in 2050, found that the gases indirectly contribute to ozone depletion. 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 percent decrease in ozone by 2050.HFCs’ contribution to ozone depletion is small compared to its predecessors. For example, trichlorofluoromethane, or CFC-11, a once common coolant that is no longer used, causes about 400 times more ozone depletion per unit mass than HFCs. Color bar for ozone depletion by hydroflourocarbons