Measuring greenhouse gas with satellites

HFC-125 is a greenhouse gas becoming a major contributor to global warming, and in the first study to use satellites to measure its concentration in the atmosphere, researchers found it has increased exponentially in the past 20 years.

The Atmospheric Chemistry Experiment, a research group at the University of Waterloo, and under contract with the Canadian Space Agency, is the first to measure from space the atmospheric concentration of HFC-125, a hydrofluorocarbon (HFC) commonly found in fire extinguishers and commercial cooling systems.

HFC-125 is among the three most-common HFCs in use in Canada. HFCs are regulated by an amendment to the Montreal Protocol, an international treaty to protect the Earth’s ozone layer. While HFCs do not deplete the ozone layer, they contribute to the warming of the planet.

Over several years, the team has measured the decline of restricted ozone-depleting substances and the increase in global ozone. Now, the researchers are focused on measuring concentrations of HFC-125 around the globe and between 11 and 25 kilometres up.

The Atmospheric Chemistry Experiment uses data from the satellite SCISAT. (Credit: Canadian Space Agency)

“Our satellite has collected data since 2004, and we have found that HFC-125 concentrations in the atmosphere are now nearly 10 times higher,” said Dr. Peter Bernath, a professor in the Faculty of Science at Waterloo and mission scientist of the Atmospheric Chemistry Experiment. “With the new international regulations, we hope to soon see a decline in this increasing rate of HFC-125 as we have with previously regulated refrigerants.”

The team’s satellite data will give climatologists more information to accurately predict climate change and reveal more about chemical reactions in the stratosphere. Before this study, the only other measurements available to climate modellers were at ground level or much lower in the atmosphere.

“After two decades in orbit and measuring more than 46 different atmospheric molecules, this solely Canadian mission has been one of the most, if not the most, successful Canadian scientific satellite missions,” Bernath said.  “We continue to find new ways to provide information to the global scientific community about molecules in the atmosphere that affect the ozone layer and global warming.”

A paper published on this study, “The first satellite measurements of HFC-125 by the ACE-FTS: Long-term trends and distribution in the Earth’s upper troposphere and lower stratosphere,” appears in Journal of Quantitative Spectroscopy and Radiative Transfer.