The ozone layer, which sits in the stratosphere between 15 km and 30 km above the earth, shields us and other living things from the sun’s excessive ultraviolet radiation[1]. Ozone depletion occurs when various ozone-depleting substances (ODS) accelerate the destruction processes, resulting in lower than normal ozone levels[3]. The Montreal Protocol, signed in 1987, has phased out around 99% of ODS, leading to a recovery of the ozone layer[2]. However, the recovery process is fragile, and scientific evidence suggests that occasional factors such as low temperatures and volcanic eruptions can still influence the ozone layer[1].
The ozone layer is on track to recover within four decades, with the global phaseout of ozone-depleting chemicals already benefiting efforts to mitigate climate change[5]. The UN-backed Scientific Assessment Panel to the Montreal Protocol on Ozone Depleting Substances confirms that the phaseout of nearly 99% of banned ozone-depleting substances has led to notable recovery of the ozone layer in the upper stratosphere and decreased human exposure to UV radiation[5]. If current policies remain in place, the ozone layer is expected to recover to 1980 values (before the appearance of the ozone hole) by 2045 over the Arctic and by 2040 for the rest of the world[5].
However, there are concerns about the potential effects of geoengineering, such as stratospheric aerosol injection (SAI), on ozone levels[5]. SAI has been proposed as a potential method to reduce climate warming by increasing sunlight reflection in the atmosphere[5]. The Scientific Assessment Panel cautions that more research is needed to understand the potential impacts of SAI on ozone levels[5].
In summary, the ozone layer is showing signs of recovery due to the global phaseout of ozone-depleting chemicals, but the process is fragile and can be influenced by various factors. The potential effects of geoengineering on ozone levels warrant further research and caution.
Citations:
[1] https://www.eea.europa.eu/en/topics/in-depth/climate-change-mitigation-reducing-emissions/current-state-of-the-ozone-layer
[2] https://www.unep.org/news-and-stories/story/rebuilding-ozone-layer-how-world-came-together-ultimate-repair-job
[3] https://www.epa.gov/ozone-layer-protection/health-and-environmental-effects-ozone-layer-depletion
[4] https://news.ucar.edu/132813/smoke-nuclear-war-would-devastate-ozone-layer-alter-climate
[5] https://www.unep.org/news-and-stories/press-release/ozone-layer-recovery-track-helping-avoid-global-warming-05degc