Ozone Layer slowly healing : Daily Current Affairs

Date: 11/01/2023

Relevance: GS-3: Climate Change and International Conventions; Ozone Layer and Montreal Protocol.

Key Phrases: Scientific Assessment of Ozone Depletion 2022, Climate Change, Climate Adaptation, COP(Conference of Parties), Montreal Protocol, Ozone Layer, Credibility, UNEP, Climate Challenge, GHGs Footprint, Chlorofluorocarbon (CFC).

Context:

Scientific Assessment of Ozone Depletion: 2022 indicates that Earth’s protective ozone layer is slowly but noticeably healing at a pace that would fully mend the hole over Antarctica in about 43 years.

Outcomes of the Report:

Major achievements of the Montreal Protocol
- Actions taken under the Montreal Protocol continued to decrease atmospheric abundances of controlled ozone-depleting substances (ODSs) and advance the recovery of the stratospheric ozone layer.
  - The atmospheric abundances of both total tropospheric chlorine and total tropospheric bromine from long-lived ODSs have continued to decline since the 2018 Assessment.
- New studies support previous Assessments in that the decline in ODS emissions due to compliance with the Montreal Protocol avoids global warming of approximately 0.5 -- 1 °C by mid-century compared to an extreme scenario with an uncontrolled increase in ODSs of 3 -- 3.5% per year.
- Actions taken under the Montreal Protocol continue to contribute to ozone recovery.
  - Recovery of ozone in the upper stratosphere is progressing.
  - Total column ozone (TCO) in the Antarctic continues to recover, notwithstanding substantial interannual variability in the size, strength, and longevity of the ozone hole.
  - TCO is expected to return to 1980 values around 2066 in the Antarctic, around 2045 in the Arctic, and around 2040 for the near-global average (60°N–60°S).
  - Compliance with the 2016 Kigali Amendment to the Montreal Protocol, which requires phase down of production and consumption of some hydrofluorocarbons (HFCs), is estimated to avoid 0.3 -- 0.5°C of warming by 2100.
Current Scientific and Policy Challenges
- The recent identification of unexpected CFC-11 emissions led to scientific investigations and policy responses.
  - Observations and analyses revealed the source region for at least half of these emissions and substantial emissions reductions followed.
  - Regional data suggest some CFC-12 emissions may have been associated with the unreported CFC-11 production.
- Unexplained emissions have been identified for other ODSs (CFCs-13, 112a, 113a, 114a, 115, and CCl4), as well as HFC-23.
  - Some of these unexplained emissions are likely occurring as leaks of feedstocks or by-products, and the remainder is not understood.
- Outside of the polar regions, observations and models are in agreement that ozone in the upper stratosphere continues to recover.
  - In contrast, ozone in the lower stratosphere has not shown signs of recovery.
  - Models simulate a small recovery in mid-latitude lower-stratospheric ozone in both hemispheres that is not seen in observations.
  - Reconciling this discrepancy is key to ensuring a full understanding of ozone recovery.
- The existing network of atmospheric monitoring stations provides measurements of global surface concentrations of long-lived ODSs and HFCs resulting from anthropogenic emissions.
  - However, gaps in regional atmospheric monitoring limit the scientific community’s ability to identify and quantify emissions of controlled substances from many source regions.
- The impact on the ozone layer of stratospheric aerosol injection (SAI), which has been proposed as a possible option to offset global warming, has been assessed following the terms of reference for the 2022 SAP Assessment Report.
  - Important potential consequences, such as deepening of the Antarctic ozone hole and delay in ozone recovery, were identified.
- Many knowledge gaps and uncertainties prevent a more robust evaluation at this time.

Montreal Protocol

The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion (known as ozone-depleting substances).
It was agreed on 16 September 1987, and entered into force on 1 January 1989.
Since then, it has undergone nine revisions including the latest one in 2016 (Kigali).
For each group of ODSs, the treaty provides a timetable on which the production of those substances must be reduced and eventually eliminated.
On 1 January 2019 the Kigali Amendment to the Montreal Protocol came into force.
- Under the Kigali Amendment countries promised to reduce the use of hydrofluorocarbons (HFCs) by more than 80% over the next 30 years.
Future Policy Considerations
- If ODS feedstock emissions as currently estimated were to be eliminated in future years, the return of mid-latitude Equivalent Effective Stratospheric Chlorine (EESC) to 1980 abundances could be advanced by almost 4 years.
- Eliminating future emissions of methyl bromide (CH3Br) from quarantine and pre-shipment applications currently allowed by the Montreal Protocol would accelerate the return of mid-latitude EESC to 1980 abundances by two years.
- Emissions of anthropogenic very short-lived chlorine substances, dominated by dichloromethane (CH2Cl2), continue to grow and contribute to ozone depletion.
- A 3% reduction in anthropogenic N2O emissions, averaged over 2023–2070, would lead to an increase in annually averaged global TCO of about 0.5 DU over the same period.
- Global emissions of long-lived HFC-23, which are largely a by-product of HCFC-22 production, are as much as eight times larger than expected and are likely to grow unless abatement increases during HCFC-22 production or feedstock use of HCFC-22 decreases.

Conclusion:

Reductions in the future emissions of CFCs and HCFCs require addressing releases from banks and continuing production and use in allowed manufacturing of feedstocks, in by-products, or in unknown uses, depending upon the compound.

Source: TheHindu

Mains Question:

Q. What are the major achievements of the Montreal Protocol? Also, discuss the current scientific and policy challenges. (150 Words).