The Earth’s protective ozone layer is slowly but visibly healing at a rate that would fully mend the hole above Antarctica by 2066 (in about 43 years), a new United Nations (UN) and World Meteorological Organization (WMO) report say.
The UN-backed panel of experts announced, during the American Meteorological Society’s 103rd annual meeting, that the ozone layer is on track to recover within four decades, with the global phaseout of ozone-depleting chemicals already benefitting efforts to mitigate climate change.
- Scientific Assessment of Ozone Depletion – 2022
- Ozone Layer Slowly Healing
- Lower Levels of Chlorine and Bromine
- Impact of Geoengineering
- Causes of Ozone Depletion
- Effects of Ozone Depletion
- How Atmospheric Ozone is Observed?
- What is Montreal Protocol?
- Impact of Montreal Protocol on Climate Change
Scientific Assessment of Ozone Depletion – 2022
The quadrennial assessment report of the UN-backed Scientific Assessment Panel to the Montreal Protocol on Ozone Depleting Substances, published every four years, confirms that the phase-out of nearly 99% of banned ozone-depleting substances has succeeded in safeguarding the ozone layer, leading to significant restoration of the hole in the ozone layer in the upper stratosphere and reduced human exposure to hazardous ultraviolet (UV) rays emanating from the sun.
Ozone Layer Slowly Healing
If the current policies are maintained, the ozone layer is anticipated to return to 1980 levels (before the ozone hole appeared), according to United Nations Environment Programme (UNEP), by 2066 over the Antarctic, by 2045 over the Arctic, and by 2040 for the rest of the planet.
‘Good news from #AMS2023: The ozone layer is on track to recover within four decades.’ World Meteorological Organization.
Particularly between 2019 and 2021, changes in the size of the ozone hole over Antarctica were mostly caused by meteorological conditions. Nonetheless, the Antarctic ozone hole has been gradually shrinking in size and depth since 2000.
Lower Levels of Chlorine and Bromine
According to Newman, Chief Earth scientist at NASA’s Goddard Space Flight Center, the two main chemicals that eat away the ozone are present in lower concentrations in the atmosphere.
According to the report, chlorine levels have declined 11.5 percent since their peak in 1993, and bromine levels, which are more efficient at eating ozone but are at lower levels in the air, have dropped 14.5 percent since their peak in 1999.
According to scientists, global emissions of the prohibited chemical chlorofluorocarbon-11, or CFC-11, which was used as a refrigerant and in insulating foams, have been decreasing since 2018, after unexpectedly growing for several years. According to the report, eastern China was responsible for a major share of the unanticipated CFC-11 emissions.
Impact of Geoengineering
Stratospheric Aerosol Injection (SAI) has been suggested by many researchers as a potential solution for reducing climate warming by boosting sunlight reflection.
According to the assessment report, an unintended consequence of SAI is that it could also affect stratospheric temperatures, and ozone production and destruction rates. It would thin the ozone layer by as much as 20 percent in Antarctica.
Causes of Ozone Depletion
Human-related Ozone Depleting Substance (ODS) emissions and the accompanying release of reactive halogen gases in the stratosphere, particularly chlorine and bromine, are the main contributors to ozone depletion. ODSs include methyl chloroform, bromine-containing halons, chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and carbon tetrachloride (CCl4).
Aside from the longer-lived ODSs, there is a large class of chlorine- and bromine-containing chemicals known as very short-lived substances (VSLSs) that are not regulated by the Montreal Protocol and have a lifespan of fewer than 6 months. Bromoform (CHBr3), for example, has a lifetime of 24 days, and chloroform (CHCl3) has a lifetime of 149 days.
Chemical reactions in the lower atmosphere often eliminate these substances. In general, only a tiny proportion of VSLS emissions reach the stratosphere, where they contribute to rising chlorine and bromine levels and ozone depletion.
Effects of Ozone Depletion
The depletion of the ozone layer exposes us to ultraviolet radiation. Ultraviolet rays are linked to skin cancer, eye cataracts, compromised immune systems, and agricultural land damage.
How Atmospheric Ozone is Observed?
Observations of stratospheric ozone are made by instruments on the ground and onboard balloons, aircraft, and satellites.
What is Montreal Protocol?
The Montreal Protocol on Substances that Deplete the Ozone Layer, as well as later modifications, adjustments, and decisions, were negotiated in order to regulate the use and production of anthropogenic ozone-depleting substances (ODSs) and certain hydrofluorocarbons (HFCs).
Impact of Montreal Protocol on Climate Change
The treaty’s beneficial effects on the climate have been confirmed by the UNEP. The Kigali Amendment to the Montreal Protocol, an additional 2016 agreement, mandates a phase-down of some HFCs’ production and consumption. It was an attempt to limit temperature increase.
Although HFCs do not directly eat up the ozone layer, they are potent climate change gases. The Kigali amendment is expected to prevent 0.3–0.5°C of warming by 2100.
WMO Secretary-General, Prof. Petteri Taalas said, “Ozone action sets a precedent for climate action. Our success in phasing out ozone-eating chemicals shows us what can and must be done – as a matter of urgency – to transition away from fossil fuels, reduce greenhouse gases and so limit temperature increase”.
The ozone layer’s restoration is an inspiring example of how nations around the world can join together to confront global concerns such as the climate crisis.