“Ozone Layer Protection” research is a mandatory one to save our environment and ecosystem. A vision of the Montreal protocol (1998) was first established and agreed, to examine various direct and indirect impacts on the ozone layer.
The main three assessment panels are:
- The Technology and Economic Assessment Panel (TEAP).
- The Scientific Assessment Panel (SAP).
- The Environmental Effects Assessment Panel (EEAP)
Earlier assessment on our global environment is carried out and updated various years as per the recommendation of panel members under Decision XI/17 (11th meeting of the parties of the Montreal Protocol, 1999), which concern about the findings of the scientific, environmental effects, and technology and economic effects.
After the implementation of the
Montreal Protocol and its subsequent amendments (World Meteorological Organization 2007), ozone depleting substances
(ODS) in the stratosphere has started to decreasing around in the late 1990s
and since then total ozone column (TOC) has started the recovery as reported in
papers using observational (in olden research) and model data [1].
Using the solar back-scatter ultraviolet merged ozone resulted from data during 1980-2016 years; the recovery of total ozone column (TOC) is examined in 5° wide latitude bands from 65 ° S to 65 ° N across the globe. Here, the variability of TOC is influenced by various natural and anthropogenic proxies. A multiple linear regression (MLR) model is employed to remove the dynamic variability.
Ningombam et al, did not identify any strong impact of TOC recovery at the equatorial regions in particular, even after using the lower stratospheric temperature in the MLR model [1]. However, some of the main concerns which are elusive in the recovery trends are
(i) Prolonged weakening or demeaning of solar cycles.
(ii) The increasing level of other ozone depleting substances (ODS) which were not part of the montreal protocol.
(iii) Impacts of climate change and its effects on dynamics of the upper atmosphere.
The updated environmental scenario is discussed by the United Nations Environment Programme (UNEP) secretary and Environmental Effects Assessment Panel (EEAP), one of three Panels informing the parties to the Montreal Protocol. The previous multiple assessment research (Photochem. Photobiol. Sci., 18, 2019, 595–828), and Bernhard et al., insisted on the findings of current and projected interactive environmental effects of ultraviolet (UV) radiation, stratospheric ozone, and climate change using the following topics [2].
- Effects on solar ultraviolet radiation due to changes in the stratospheric ozone layer and its interaction with climate.
- The effects of exposure to solar ultraviolet radiation on human health.
- Plant and terrestrial ecosystem response to changes in UV radiation and climate.
- Effects of stratospheric ozone depletion, UV radiation and interactions with climate change on aquatic ecosystems.
- Interactions of biogeochemical cycles with changing UV radiation and climate.
- Interaction of changes in stratospheric ozone with air quality in a changing climate.
- Interactive effects of solar UV radiation and climate change on material damage.
Figure 1. June and December climatology of DNA-damaging fluence rate [3].
We must to be aware of these effects in present and future views, which include those on human health, air quality, ecosystems (terrestrial and aquatic), biogeochemical cycles, and materials used in human needs. UV light exposure on organisms and materials in ecosystems reveals the interactive effects of climate change factors. Hence, it has implications for the atmosphere, feedbacks, contaminant fate and transport, organismal responses, and outdoor materials (plastics, wood, and fabrics). We have also think to avoid/reduce/reuse the ozone depleting substance (chlorofluorocarbons, halon, carbon tetrachloride, methyl chloroform, hydrobromofluorocarbons, Hydrochlorofluorocarbons, methyl bromide, bromochloromethane), which chemicals that destroys the earth’s protective ozone layer.
The universal ratification of the Montreal Protocol, agreed by 197 countries, has led to the regulation and phase-out of chemicals that deplete the stratospheric ozone layer. Although this treaty has unprecedented success in protecting the ozone layer, and hence all life on Earth from damaging UV radiation, it is also making a substantial contribution to reducing climate warming because many of the chemicals under this treaty are greenhouse gases. However, terrestrial and aquatic ecosystems provide essential services on human health which well-being ultimately depend. In addition to be critical to our well-being, environmental sustainability and the maintenance of biodiversity are also important at a higher level if we are able to maintain a healthy planet [4].
Scientists categorize UV light into three different subtypes are UV-A light (320-400nm), UV-B light (290-320nm), and UV-C light (100-290nm). In UV-A is UV light with the longest wavelength, and the least harmful. UV-B light causes sunburns with prolonged exposure along with increasing the risk of skin cancer and other cellular damage. About 95% of all UV-B light is absorbed by the ozone in Earth's atmosphere. UV-C light is extremely harmful and is almost completely absorbed by Earth's atmosphere. It is commonly used as a disinfectant in food, air, and water to kill microorganisms by destroying their cells' nucleic acids.
Depletion of stratospheric ozone leads to increased UV-B radiation at the Earth’s surface that can directly affect organisms and their environment. Due to the success of the Montreal Protocol, present-day increases in UV-B radiation (quantified as clear-sky UV Index) due to stratospheric ozone depletion have been negligible in the tropics, small (5–10%) at mid-latitudes and large only in Antarctica. A recovery time of stratospheric ozone over the many decades, the clear-sky noon-time UV Index is expected to decrease (for example, by 2–8% at mid-latitudes depending on season and precise location, and by 35% during the Antarctic October ozone ‘hole’). Independent of stratospheric ozone variations, climate change is increasingly contributing to changes in incident surface UV-B radiation. Unlike stratospheric ozone depletion, these effects driven by climate change will modify the amount of surface solar radiation not just in the UV-B but also in the ultraviolet-A and visible (400–700 nm) parts of the spectrum. This exposure of UV-B leads to exchange the environmental and climate issues.
This topic was covered by the UNEP EEAP Quadrennial Assessment result [5], embrace the full complexity and inter-relatedness of our living planet, and the outcomes of the Montreal Protocol (and Amendments and Adjustments) was demonstrated a globally united and successful actions on complex environmental issues that are possible.
References
S. P. Ningombam et al., Atmo.Res. 232, 104686 (2020).
G. H. Bernhard et al., Photochem. Photobiol. Sci., 19, 542 (2020).
S. Madronich et al., Photochem. Photobiol. Sci. 17, 1918 (2018).
Millenium Ecosystem Assessment. Ecosystems and Human Well-being: Our Human Planet; Summary for Decision-makers, Vol. 5 (Island, 2005).
P. W. Barnes et al., Nature sustainability 2, 569 (2019).
Blog Written By
Dr. K. Rajkumar
Central University of Tamilnadu
Thiruvarur, Tamil Nadu, India
Editors
Dr. A. S. Ganeshraja
Dr. S. Chandrasekar
Reviewers
Dr. Y. Sasikumar
Dr. K. Vaithinathan
Dr. S. Thirumurugan
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