Reconciliation of halogen-induced ozone loss with the total-column ozone record (original) (raw)
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Photochemical and Photobiological Sciences, 2023
Ultraviolet (UV) radiation drives the net production of tropospheric ozone (O 3) and a large fraction of particulate matter (PM) including sulfate, nitrate, and secondary organic aerosols. Ground-level O 3 and PM are detrimental to human health, leading to several million premature deaths per year globally, and have adverse effects on plants and the yields of crops. The Montreal Protocol has prevented large increases in UV radiation that would have had major impacts on air quality. Future scenarios in which stratospheric O 3 returns to 1980 values or even exceeds them (the so-called super-recovery) will tend to ameliorate urban ground-level O 3 slightly but worsen it in rural areas. Furthermore, recovery of stratospheric O 3 is expected to increase the amount of O 3 transported into the troposphere by meteorological processes that are sensitive to climate change. UV radiation also generates hydroxyl radicals (OH) that control the amounts of many environmentally important chemicals in the atmosphere including some greenhouse gases, e.g., methane (CH 4), and some short-lived ozone-depleting substances (ODSs). Recent modeling studies have shown that the increases in UV radiation associated with the depletion of stratospheric ozone over 1980-2020 have contributed a small increase (~ 3%) to the globally averaged concentrations of OH. Replacements for ODSs include chemicals that react with OH radicals, hence preventing the transport of these chemicals to the stratosphere. Some of these chemicals, e.g., hydrofluorocarbons that are currently being phased out, and hydrofluoroolefins now used increasingly, decompose into products whose fate in the environment warrants further investigation. One such product, trifluoroacetic acid (TFA), has no obvious pathway of degradation and might accumulate in some water bodies, but is unlikely to cause adverse effects out to 2100. This Perspective is part of the topical collection: Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, 2022 Quadrennial Assessment.
Ozone, Climate, and Global Atmospheric Change
Science Activities Classroom Projects and Curriculum Ideas, 1992
was selected as Virginia's Outstanding Scientist for 1987. Also a recipient of the NASA Medal for Exceptions(scientific Achievement, Dr. ~~~i~~ concentrations of the trace gases are measured in terms of wrote the lead article in the Febmfy-March 1981 issue of Science Activities, entitled "The Early Atmosphere: A New Picture." in addition, Dr. Levine edited and contributed to The Photochemistry of Atmospheres: Earth, the Other Planets, and centimeter of air. Trace gases such as ozone (O& carbon Comets, published by Academic Press, Inc., in 1985, and Global-Biomass Burning: Atmospheric, Climatic, and BIospheric dioxide (CO,), methane (CH4), nitrous oxide (N20), chl~rofluorocarbons (CFCs), and halons (brominated CFCs) are measured in parts per million by volume ppmv), parts per billion by volume ppbv), or parts per trillion by volume (pptv). The concentrations of the major and-implIcatIons, published by the MIT Press, Inc., in 1991. http:Nasd-www.larc.nasa.gov/biomassburn/ozone.html 101'2 112004 Ozone, Climate, and Global Atmos Change Table 1-Major and Sdmd 1-Gmes m the Atmoaphere G-Concentration Nitrogen (NJ Oxygen [Od Argon jAr) Water vawr (HLOf 78.08 percent by volume 20.95 percent by vdume 0.93 percent by volume 0 to 1 or 2 percent by wlurne Carbon dioxide (03,) 350 P P W ozone to3 In troposphere In stratosphece 0.02 lo 0.1 ppmu 0.1 rn 10 ppmv Methane [CH,) 1.7 ppmv CFC-12 (CF2ClJ 0.5 ppbv Nitrous oxide {Npf 031 P P CFC-i i [ma,) 0.3 ppbv Habn-1301 (Cf3rF.J 2.0 pptr Halon-121 1 [CBrCIF,) 1.7 pptv Lust Updated: 1 O/OlL?OO2 12:43:45 Web Citrator: P. Kay Costulis (p. k. c o s t i c I i s~l~n r~.. i~~~a~~~~) Responsible NASA Oficial: Dr. Joel S. Levine. Atmospheric Scieiices Conipetericj h ttp://asd-www. larc .nasa.gov/biomass-bundozone. h tml
Photochemical & Photobiological Sciences, 2011
Air pollution will be directly influenced by future changes in emissions of pollutants, climate, and stratospheric ozone, and will have significant consequences for human health and the environment. UV radiation is one of the controlling factors for the formation of photochemical smog, which includes tropospheric ozone (O 3) and aerosols; it also initiates the production of hydroxyl radicals (∑ OH), which control the amount of many climate-and ozone-relevant gases (e.g., methane and HCFCs) in the atmosphere. Numerical models predict that future changes in UV radiation and climate will modify the trends and geographic distribution of ∑ OH, thus affecting the formation of photochemical smog in many urban and regional areas. Concentrations of ∑ OH are predicted to decrease globally by an average of 20% by 2100, with local concentrations varying by as much as a factor of two above and below current values. However, significant differences between modelled and measured values in a limited number of case studies show that chemistry of hydroxyl radicals in the atmosphere is not fully understood. Photochemically produced tropospheric ozone is projected to increase. If emissions of anthropogenic air pollutants from combustion of fossil fuels, burning of biomass, and agricultural activities continue to increase, concentrations of tropospheric O 3 will tend to increase over the next 20-40 years in certain regions of low and middle latitudes because of interactions of emissions, chemical processes, and climate change. Climate-driven increases in temperature and humidity will also increase production of tropospheric O 3 in polluted regions, but reduce it in more pristine regions. Higher temperatures tend to increase emissions of nitrogen oxides (NO x) from some soils and release of biogenic volatile organic compounds (VOCs) from vegetation, leading to greater background concentrations of ozone in the troposphere. The net effects of future changes in UV radiation, meteorological conditions, and anthropogenic emissions may be large, thus posing challenges for prediction and management of air quality. Aerosols composed of organic substances have a major role in both climate and air quality, and contribute a large uncertainty to the energy budget of the atmosphere. These aerosols are mostly formed via the UV-initiated oxidation of VOCs from anthropogenic and biogenic sources, although the details of the chemistry are still poorly understood and current models under-predict their abundance. A better understanding of their formation, chemical composition, and optical properties is required to assess their significance for air quality and to better quantify their direct and indirect radiative forcing of climate. Emissions of compounds containing fluorine will continue to have effects on the chemistry of the atmosphere and on climate change. The HCFCs and HFCs used as substitutes for ozone-depleting CFCs can break down into trifluoroacetic acid (TFA), which will accumulate in oceans, salt lakes, and playas. Based on historical use and projections of future uses, including new products entering the market, such as the fluoro-olefins, increased loadings of TFA in these environmental sinks will be small. Even when added to existing amounts from natural sources, risks to humans or the environment from the historical use of CFCs or continued use of their replacements is judged to be negligible.
Photochemical and Photobiological Sciences, 2004
The parties to the Montreal Protocol are informed by three panels of experts. One of these is the Environmental Effects Assessment Panel (EEAP), which deals with UV radiation and its effects on human health, animals, plants, biogeochemistry, air quality and materials. Since 2000, the analyses and interpretation of these effects have included interactions between UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than believed previously. As a result of this, human health and environmental problems will likely be longer-lasting and more regionally variable. Like the other panels, the EEAP produces a detailed report every four years; the most recent was that for 2006 (Photochem. Photobiol. Sci., 2007, 6, 201-332). In the years in between, the EEAP produces a less detailed and shorter progress report, as is the case for this present one for 2009. A full quadrennial report will follow for 2010. Ozone and changes in biologically active UV radiation reaching the Earth's surface ∑ Long-term changes in surface UV irradiance vary geographically. In some cases, the response of surface UV radiation ‡ to the beginning of an ozone recovery is apparent, but in others UV radiation is still increasing Since the mid-1990s, irradiance changes within the United States Department of Agriculture's UV Network ranged from-5% to +2% per decade, 1 although, in most cases, the trends for individual months were not statistically significant. Over the measurement period of approximately one decade , there was a general increase in ozone, suggesting that changing cloud, aerosol, air pollution, and snow conditions were responsible for driving surface radiation variability in addition to ozone trends. At Belsk, Poland, an increase in column ozone and levelling off of UV irradiance since 1995 has been identified from observations spanning the period 1976 to 2006. 2 Analysis of satellite data 3 revealed significant increases in UV irradiance from 1979 to 1998 at all latitudes, except the equatorial zone, which were caused by decreases in total ozone. For clear skies, the largest increases in UV since ∑ Using information about season, sun angle, and daily sunshine duration alone, daily totals of solar UV radiation back to 1893 were reconstructed for central Europe 15 Extrapolation prior to the period when ozone column measurements became available was based on the fact that UV changes since 1979 were not highly correlated with ozone. The
Photochemical & Photobiological Sciences, 2008
The parties to the Montreal Protocol are informed by three panels of experts. One of these is the Environmental Effects Assessment Panel (EEAP), which deals with UV radiation and its effects on human health, animals, plants, biogeochemistry, air quality and materials. Since 2000, the analyses and interpretation of these effects have included interactions between UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than believed previously. As a result of this, human health and environmental problems will likely be longer-lasting and more regionally variable. Like the other panels, the EEAP produces a detailed report every four years; the most recent was that for 2006 (Photochem. Photobiol. Sci., 2007, 6, 201-332). In the years in between, the EEAP produces a less detailed and shorter progress report, as is the case for this present one for 2009. A full quadrennial report will follow for 2010. Ozone and changes in biologically active UV radiation reaching the Earth's surface ∑ Long-term changes in surface UV irradiance vary geographically. In some cases, the response of surface UV radiation ‡ to the beginning of an ozone recovery is apparent, but in others UV radiation is still increasing Since the mid-1990s, irradiance changes within the United States Department of Agriculture's UV Network ranged from-5% to +2% per decade, 1 although, in most cases, the trends for individual months were not statistically significant. Over the measurement period of approximately one decade , there was a general increase in ozone, suggesting that changing cloud, aerosol, air pollution, and snow conditions were responsible for driving surface radiation variability in addition to ozone trends. At Belsk, Poland, an increase in column ozone and levelling off of UV irradiance since 1995 has been identified from observations spanning the period 1976 to 2006. 2 Analysis of satellite data 3 revealed significant increases in UV irradiance from 1979 to 1998 at all latitudes, except the equatorial zone, which were caused by decreases in total ozone. For clear skies, the largest increases in UV since ∑ Using information about season, sun angle, and daily sunshine duration alone, daily totals of solar UV radiation back to 1893 were reconstructed for central Europe 15 Extrapolation prior to the period when ozone column measurements became available was based on the fact that UV changes since 1979 were not highly correlated with ozone. The
Tropospheric Ozone Assessment Report
Elementa: Science of the Anthropocene, 2020
Our understanding of the processes that control the burden and budget of tropospheric ozone has changed dramatically over the last 60 years. Models are the key tools used to understand these changes, and these underscore that there are many processes important in controlling the tropospheric ozone budget. In this critical review, we assess our evolving understanding of these processes, both physical and chemical. We review model simulations from the International Global Atmospheric Chemistry Atmospheric Chemistry and Climate Model Intercomparison Project and Chemistry Climate Modelling Initiative to assess the changes in the tropospheric ozone burden and its budget from 1850 to 2010. Analysis of these data indicates that there has been significant growth in the ozone burden from 1850 to 2000 (approximately 43 ± 9%) but smaller growth between 1960 and 2000 (approximately 16 ± 10%) and that the models simulate burdens of ozone well within recent satellite estimates. The Chemistry Clim...