2012 News & Events

Ravishankara Leads International Report on Hydrofluorocarbons (HFCs)

17 January 2012

report cover
A copy of the report is available from UNEP.

Dr. A.R. Ravishankara, Director of CSD, recently completed work as a Lead Author of a special Synthesis Report of the United Nations Environment Programme, HFCs: A Critical Link in Protecting Climate and the Ozone Layer This report was key input for a November meeting of the Montreal Protocol, the international agreement that protects the ozone layer.

HFCs (hydrofluorocarbons) are entirely manmade substances that were introduced for use as substitutes for ozone-depleting substances in applications such as refrigeration, air conditioning, and foam products.

HFCs do not deplete the ozone layer; however, many are potent greenhouse gases. Although currently their contribution to climate forcing is less than one percent, HFCs are rapidly increasing in the atmosphere as they are widely adopted as ozone-friendly substitutes. Thus, they have the potential to substantially influence the future climate. They could even largely "undo" the climate benefits that have been achieved by the Montreal Protocol ozone-layer agreement, which, in curtailing the use of ozone-depleting substances (ODSs), also benefitted climate because many ODSs are greenhouse gases.

The new report outlines the current understanding related to HFCs and climate change, and explores alternatives to the use of HFCs that are most harmful to climate. The report reaches several conclusions:

  • While various options are being evaluated or further developed to reduce HFC emissions, there is no "one-size-fits-all" solution.
  • Ozone-friendly and climate-friendly alternatives exist for HFCs in a number of different sectors, but further work needs to be done in order to realize the full advantages of the alternatives.
  • With further work, sustainable options for protecting both the ozone layer and the global climate are likely to be found.

The report informed the discussions at the November 2011 meeting of the Parties to the Montreal Protocol. Some nations have proposed possible new actions to reduce the use of HFCs that strongly affect climate. During that meeting, Ravi gave a presentation on the new HFC report and answered many questions posed by the delegates.

Ravi was one of the four-member Lead Author team, which included Guus Velders (Netherlands), Melanie Miller (Belgium), and Mario Molina (Mexico and USA). CSD scientist John Daniel served as a scientific and technical reviewer, and also contributed data and information. David Fahey (CSD) and Steve Montzka (GMD) were contributors. The content of the HFC report relied heavily upon the most recent scientific assessment report about the ozone layer, Scientific Assessment of Ozone Depletion: 2010, for which NOAA provided leadership and many of the scientific studies that were referenced. Peer-reviewed journal articles authored by NOAA scientists were also heavily referenced in the HFC report, especially papers in the last few years that have quantified the climate benefits that have accrued from the Montreal Protocol.