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Deniz Ural

Question 16: Has the Montreal Protocol been successful in reducing ozone-depleting substances in the atmosphere?. Deniz Ural. YES! ODS * decrease after Montreal Protocol (MP). ODS reduction depends on how rapidly an ODS is used and released to the atmosphere after being produced

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Deniz Ural

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  1. Question 16:Has the Montreal Protocol been successful in reducing ozone-depleting substances in the atmosphere? Deniz Ural

  2. YES! • ODS* decrease after Montreal Protocol (MP). • ODS reduction depends on • how rapidly an ODS is used and released to the atmosphere after being produced • the lifetime (τ) for the removal of the ODS from the atmosphere. Short τ  faster removal and no storage • EESC**: • Measure of success of MP. • Measure of potential Ozone depletion in the stratosphere that can be calculated from atmospheric surface abundance of ODS and natural chlorine and bromine containing gasses. • How to calculate: measurements, past values, projections • Long term trend: 1950-1990: steady increase, after MP: slow down of increase and started to decrease. Back to 1980 values will take several decades. * ODS: Ozone depleting substance ** EESC: Effective Equivalent Stratospheric Chlorine

  3. CFC: τ = 45-100 years. Ended in 1996 (developed countries) and 2010 (developing countries). • Halons: Bromine containing ODS. τ = 65 years. Ended in 1994 and 2010. • MethylChloroform: τ = 5 years. No storage. Ended in 1996 and 2015. • HCFCsubstitutegases: Lesser threat to Ozone. Increasing trend. Phase out in 2020 and 2030. • Carbontetrachloride: Phased out in 1996 and 2010. Less rapid decrease then expected.  either larger than reported emissions or τ is longer than estimated. • Methylchloridemethylbromide: distinct among halogen source gases because substantial fractions of their emissions are associated with natural processes.

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