30 research outputs found
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Synthesis and Assessment Product
This Synthesis and Assessment Product (SAP 2.4) focuses on the Climate models. Depletion of the stratospheric ozone layer by human-produced ozone-depleting substances has been recognized as a global environmental issue for more than three decades, and the international effort to address the issue via the United Nations Montreal Protocol marked its 20-year anniversary in 2007. Scientific understanding underpinned the Protocol at its inception and ever since. As scientific knowledge advanced and evolved, the Protocol evolved through amendment and adjustment. Policy-relevant science has documented the rise, and now the beginning decline, of the atmospheric abundances of many ozone-depleting substances in response to actions taken by the nations of the world. Projections are for a return of ozone-depleting chemicals (compounds containing chlorine and bromine) to their "pre-ozone-depletion" (pre-1980) levels by the middle of this century for the midlatitudes; the polar regions are expected to follow suit within 20 years after that. Since the 1980s, global ozone sustained a depletion of about 5 percent in the midlatitudes of both the Northern Hemisphere and Southern Hemisphere, where most of the Earth's population resides; it is now showing signs of turning the corner towards increasing ozone. The large seasonal depletions in the polar regions are likely to continue over the next decade but are expected to subside over the next few decades
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Instrumentation and Measurement Strategy for the NOAA SENEX Aircraft Campaign as Part of the Southeast Atmosphere Study 2013
Natural emissions of ozone-and-aerosol-precursor gases such as isoprene and monoterpenes are high in the southeast of the US. In addition, anthropogenic emissions are significant in the Southeast US and summertime photochemistry is rapid. The NOAA-led SENEX (Southeast Nexus) aircraft campaign was one of the major components of the Southeast Atmosphere Study (SAS) and was focused on studying the interactions between biogenic and anthropogenic emissions to form secondary pollutants. During SENEX, the NOAA WP-3D aircraft conducted 20 research flights between 27 May and 10 July 2013 based out of Smyrna, TN. Here we describe the experimental approach, the science goals and early results of the NOAA SENEX campaign. The aircraft, its capabilities and standard measurements are described. The instrument payload is summarized including detection limits, accuracy, precision and time resolutions for all gas-and-aerosol phase instruments. The inter-comparisons of compounds measured with multiple instruments on the NOAA WP-3D are presented and were all within the stated uncertainties, except two of the three NO2 measurements. The SENEX flights included day- and nighttime flights in the Southeast as well as flights over areas with intense shale gas extraction (Marcellus, Fayetteville and Haynesville shale). We present one example flight on 16 June 2013, which was a daytime flight over the Atlanta region, where several crosswind transects of plumes from the city and nearby point sources, such as power plants, paper mills and landfills, were flown. The area around Atlanta has large biogenic isoprene emissions, which provided an excellent case for studying the interactions between biogenic and anthropogenic emissions. In this example flight, chemistry in and outside the Atlanta plumes was observed for several hours after emission. The analysis of this flight showcases the strategies implemented to answer some of the main SENEX science questions
Potential rates and environmental controls of denitrification and nitrous oxide production in a temperate urbanized estuary
EmissĂľes de Ăłxido nitroso em ĂĄguas fluviais nĂŁo poluĂdas e poluĂdas da Bacia do Rio Paquequer (TeresĂłpolis, Rio de Janeiro)
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Lower stratospheric processes
Chapter 7 of Scientific Assessment of Ozone Depletion: 199
The Precautionary Principle and the Environment: A Case Study of an Immediate Global Response to the Molina and Rowland Warning
In 1974, Mario J. Molina and F. Sherwood Rowland warned that chlorofluorocarbons (CFCs) could destroy the stratospheric ozone layer, which protects Earth against the harmful effects of ultraviolet radiation [Molina and Rowland Nature 1974, 249, 810]. In 1975, Ramanathan warned that CFCs are powerful greenhouse gases (GHGs) and would rival carbon dioxide (CO2) in causing climate change if left unabated [Ramanathan Science 1975, 190, 50]. The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer (Protocol), arguably the most successful global environmental treaty in history, was enacted in response to these warnings. This Protocol has phased out almost 99% of the production and consumption of ozone depleting substances (ODSs). Other papers have explored the âworld avoidedâ by actions under the Protocol [Prather et al. Nature 1996, 381, 551; Newman et al. Atmos. Chem. Phys. 2009, 9, 2113; Morgenstern et al. Geophys. Res. Lett. 2008, 35, 1]. They concluded that the ozone layer would have been highly depleted across the globe by the mid-21st century without the Protocol and that the Protocol contributed significantly to reduce climate change. This paper explores what could have been achieved if the world had acted against the continued use of ODSs, which were both ozone-depleting and greenhouse gases, immediately after Molina and Rowland warned of stratospheric ozone depletion and Ramanathan warned of climate forcing using chemicals and technology that were already globally available in the mid-1970s. We show that such âprecautionary principleâ actions would have reduced global ozone layer depletion, reduced the extent of the ozone hole, brought forward the dates for ozone layer recovery, and helped minimize climate change
The Precautionary Principle and the Environment: A Case Study of an Immediate Global Response to the Molina and Rowland Warning
In 1974, Mario J. Molina and F. Sherwood Rowland warned that chlorofluorocarbons (CFCs) could destroy the stratospheric ozone layer, which protects Earth against the harmful effects of ultraviolet radiation [Molina and Rowland Nature 1974, 249, 810]. In 1975, Ramanathan warned that CFCs are powerful greenhouse gases (GHGs) and would rival carbon dioxide (CO2) in causing climate change if left unabated [Ramanathan Science 1975, 190, 50]. The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer (Protocol), arguably the most successful global environmental treaty in history, was enacted in response to these warnings. This Protocol has phased out almost 99% of the production and consumption of ozone depleting substances (ODSs). Other papers have explored the âworld avoidedâ by actions under the Protocol [Prather et al. Nature 1996, 381, 551; Newman et al. Atmos. Chem. Phys. 2009, 9, 2113; Morgenstern et al. Geophys. Res. Lett. 2008, 35, 1]. They concluded that the ozone layer would have been highly depleted across the globe by the mid-21st century without the Protocol and that the Protocol contributed significantly to reduce climate change. This paper explores what could have been achieved if the world had acted against the continued use of ODSs, which were both ozone-depleting and greenhouse gases, immediately after Molina and Rowland warned of stratospheric ozone depletion and Ramanathan warned of climate forcing using chemicals and technology that were already globally available in the mid-1970s. We show that such âprecautionary principleâ actions would have reduced global ozone layer depletion, reduced the extent of the ozone hole, brought forward the dates for ozone layer recovery, and helped minimize climate change