Newly detected ozone-depleting substances in the atmosphere

SAP Presentation

OEWG, Paris, 14-18 July 2014

These gases are listed in the Montreal Protocol.

• CFC-112 (CFCl2CFCl2) – under Annex B

• CFC-112a (CF2ClCCl3) – under Annex B

• CFC-113a (CF3CCl3) – under Annex A

• HCFC-133a (CF3CH2Cl) – under Annex C. Regulated under Article 2F

What are these newly found compounds?

GWPs and radiative efficiencies are derived from a new study by

Etminan et al. (2014).

aOnly one study to date. bBased on a mixture of -112 and -112a

CFC-112 CFC-112a

CFC-113a HCFC-133a

51 yr

51 yr

44 yr

4.3 yr

1965 1975 1985 1995 2005

1965 1975 1985 1995 20051965 1975 1985 1995 2005

1965 1975 1985 1995 2005

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How are these newly found compounds evolving?

Laube et al. (2014) Figure 1

CFC-112 and -112a are both declining

Emissions have also declined

CFC-113a and HCFC-133a are increasing

rapidly

Emissions are increasing

The levels of the new compounds are not particularly high when measured against other ODSs

• These are not new compounds, but now detected in the atmosphere

• Current 2013 levels of global effective equivalent stratospheric chlorine (EESC) is about 1700 parts per trillion (ppt)

• The maximum contribution of these new CFCs is about 4 ppt of EESC - this is <0.2% of the global EESC total.

• The maximum 2011 emissions contribution is about 8,000 Gg CO2-Eq per yr. This is <0.5% of the global 2011 ODS GWP weighted emissions.

What are the sources?• CFC-112 and -112a (decreasing): may have

been used as feedstock chemicals for fluorovinyl ether production and also as solvents for cleaning electronics. For CFC-112, 1989-2001 production has been reported but only small quantities. No CFC-112a production reports have been released - it may have been reported as CFC-112.

• CFC-113a (increasing): emissions could be related to usage as an intermediate for HFC-134a production. Also used as a feedstock for insecticide production (cyhalotrin and tefluthrin).

• HCFC-133a (increasing): used in the production of pharmaceuticals and is an intermediate product in HFC-134a production (TEAP, 2012).

Summary• CFC-112, CFC-112a, CFC-113a, HCFC-133a have been newly

discovered by analysis of air samples and from air trapped in snow. These compounds are included under the Protocol.

• All of these gases are ozone depleting substances and greenhouse gases.

• Concentrations are currently quite small in comparison to levels of other ODSs in the atmosphere. Not currently significant for ozone depletion and climate forcing.

• CFC-112 and CFC-112a are decreasing• CFC-113a and HCFC-133a are increasing• Details on these gases will be found in the SAP 2014 Scientific

Assessment

Thank you for your attention!

Thanks for contributions from Keith Shine, Johannes Laube, Guus Velders,

Lambert Kuijpers, David Sherry, Stefan Reimann, Maryam Etminan

Other matters

• HFO-1233zd, lifetime = 40 days, – ODP = 0.00034 (strongly dependent on

emission location)