Multimodel ensemble simulations of present-day and near-future tropospheric ozone

Journal of Geophysical Research Atmospheres (Impact Factor: 3.43). 04/2006; 111:D08301. DOI: 10.1029/2005JD006338
Source: OAI


Global tropospheric ozone distributions, budgets, and radiative forcings from an ensemble of 26 state-of-the-art atmospheric chemistry models have been intercompared and synthesized as part of a wider study into both the air quality and climate roles of ozone. Results from three 2030 emissions scenarios, broadly representing “optimistic,” “likely,” and “pessimistic” options, are compared to a base year 2000 simulation. This base case realistically represents the current global distribution of tropospheric ozone. A further set of simulations considers the influence of climate change over the same time period by forcing the central emissions scenario with a surface warming of around 0.7K. The use of a large multimodel ensemble allows us to identify key areas of uncertainty and improves the robustness of the results. Ensemble mean changes in tropospheric ozone burden between 2000 and 2030 for the 3 scenarios range from a 5% decrease, through a 6% increase, to a 15% increase. The intermodel uncertainty (±1 standard deviation) associated with these values is about ±25%. Model outliers have no significant influence on the ensemble mean results. Combining ozone and methane changes, the three scenarios produce radiative forcings of −50, 180, and 300 mW m−2, compared to a CO2 forcing over the same time period of 800–1100 mW m−2. These values indicate the importance of air pollution emissions in short- to medium-term climate forcing and the potential for stringent/lax control measures to improve/worsen future climate forcing. The model sensitivity of ozone to imposed climate change varies between models but modulates zonal mean mixing ratios by ±5 ppbv via a variety of feedback mechanisms, in particular those involving water vapor and stratosphere-troposphere exchange. This level of climate change also reduces the methane lifetime by around 4%. The ensemble mean year 2000 tropospheric ozone budget indicates chemical production, chemical destruction, dry deposition and stratospheric input fluxes of 5100, 4650, 1000, and 550 Tg(O3) yr−1, respectively. These values are significantly different to the mean budget documented by the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). The mean ozone burden (340 Tg(O3)) is 10% larger than the IPCC TAR estimate, while the mean ozone lifetime (22 days) is 10% shorter. Results from individual models show a correlation between ozone burden and lifetime, and each model's ozone burden and lifetime respond in similar ways across the emissions scenarios. The response to climate change is much less consistent. Models show more variability in the tropics compared to midlatitudes. Some of the most uncertain areas of the models include treatments of deep tropical convection, including lightning NO x production; isoprene emissions from vegetation and isoprene's degradation chemistry; stratosphere-troposphere exchange; biomass burning; and water vapor concentrations.

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Available from: Twan van Noije, Sep 29, 2015
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    • "As soon as variations occur, they have to detect the stress and turn on a whole battery of mechanisms leading to acclimation. Nowadays, due to anthropic activities, ozone (O 3 ) is a more and more widespread pollutant with concentration peaks usually occurring in spring and summer, and a constant increase of its ground levels since the pre-industrial period (Stevenson et al., 2006). O 3 affects plants in different manners, depending on its concentration (Renaut et al., 2009). "
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    ABSTRACT: All along their life, plants and trees are exposed to various stresses, and particularly to abiotic ones. Ozone (O3) is one of the most important air pollutants, whose ground levels keep increasing as a result of climate change. High O3 concentrations deeply affect plants and cells, and impact worldwide crop and forest production. In plant leaves, O3 directly interferes with surface tissues or reaches mesophyll cells through stomata. In this case, O3 is almost immediately degraded into reactive oxygen species (ROS) in the apoplastic space of plant cells. For plants to acclimate to O3, the O3 stress signal has to be perceived at the cellular level and relayed to the nucleus to lead to cell reprogramming. The aim of this review is to focus on different O3-sensing localizations, i.e., epicuticular waxes, the cell wall and the plasma membrane, and to detail the different early signaling components related to these sites – in particular lipids, membrane proteins (G proteins, NADPH oxidases and ion channels) and MAP kinases. Finally, some interesting putative membrane-related O3 signaling components are presented as clues to be validated in future investigations.
    Environmental and Experimental Botany 06/2015; 114. DOI:10.1016/j.envexpbot.2014.11.012 · 3.36 Impact Factor
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    • "Among all explanations, it is crucial to note that the present findings underline a potential global warming-related ecotoxicological risk for aquatic organisms, mainly derived from the toxicity variations of single or more complex mixtures of environmental pollutants. Therefore, this study supports the growing body of evidence that rising temperatures will have broad negative impacts on the distribution and toxicity of environmental contaminants (Macdonald et al., 2003, 2005; Knowlton et al., 2004; Knowlton and Kinney, 2004; Dentener et al., 2006; Stevenson et al., 2006; Bell et al., 2007; Buckman et al., 2007; Patra et al., 2007; Schiedek et al., 2007; Noyes et al., 2009). Further implementations in terms of experimental studies and modelling are needed to test various scenarios concerning transport , transfer, bioavailability as well as the final fate of all environmentally relevant pollutants, assessing the impacts on fitness and population/ecosystem effects on key species (Wu, 1995; Vaughan and Smith, 1996; Mezcua et al., 2006; Sarmah et al., 2006). "
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    • "The increase was, however, somewhat slower during the 1990s in comparison with the 1970s and 1980s. The rise of the background ozone levels in the future was also predicted by Stevenson et al. (2006) by as much as 5 to 16 %. The expected rise of the ozone levels in the region was one of the arguments for starting the TOR-subproject of EUROTRAC in 1988. "
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    ABSTRACT: Monitoring data on ambient ozone collected at the Puntijarka station located on the mountain Medvednica 980 m a.s.l. and 10 km to the north of the Croatian capital Zagreb during a 21-year period (1989-2009) have been analysed in order to check whether any regularities such as periodicities or trends in the data could be detected. Only two types of cycles could be observed: an annual cycle with higher ozone fractions during spring and summer and a diurnal cycle with the highest values at noon and in the early afternoon. Both can be related to insolation with the same periodicity confirming the photochemical nature of ozone formation. Conclusions about trends are less pronounced; for the first decade of the observational period no significant trend was found and for the second decade there was a significantly negative trend of –1.38 ppb yr–1
    Journal of Atmospheric Chemistry 12/2014; 71(4):1. DOI:10.1007/s10874-014-9294-9 · 1.95 Impact Factor
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