Introduction of high-performing crop cultivars and crop/soil water management practices that increase the stomatal uptake of carbon dioxide and photosynthesis will be instrumental in realizing the United Nations Sustainable Development Goal (SDG) of achieving food security. To date, however, global assessments of how to increase crop yield have failed to consider the negative effects of tropospheric ozone, a gaseous pollutant that enters the leaf stomatal pores of plants along with carbon dioxide, and is increasing in concentration globally, particularly in rapidly developing countries. Earlier studies have simply estimated that the largest effects are in the areas with the highest ozone concentrations. Using a modelling method that accounts for the effects of soil moisture deficit and meteorological factors on the stomatal uptake of ozone, we show for the first time that ozone impacts on wheat yield are particularly large in humid rain-fed and irrigated areas of major wheat-producing countries (e.g. United States, France, India, China and Russia). Averaged over 2010-2012, we estimate that ozone reduces wheat yields by a mean 9.9% in the northern hemisphere and 6.2% in the southern hemisphere, corresponding to some 85 Tg (million tonnes) of lost grain. Total production losses in developing countries receiving Official Development Assistance are 50% higher than those in developed countries, potentially reducing the possibility of achieving UN SDG2. Crucially, our analysis shows that ozone could reduce the potential yield benefits of increasing irrigation usage in response to climate change because added irrigation increases the uptake and subsequent negative effects of the pollutant. We show that mitigation of air pollution in a changing climate could play a vital role in achieving the above-mentioned UN SDG, while also contributing to other SDGs related to human health and well-being, ecosystems and climate change.
Abstract. The impact of climate change on surface ozone over Europe was studied using four offline regional chemistry transport models (CTMs) and one online regional integrated climate-chemistry model (CCM), driven by the same global projection of future climate under the SRES A1B scenario. Anthropogenic emissions of ozone precursors from RCP4.5 for year 2000 were used for simulations of both present and future periods in order to isolate the impact of climate change and to assess the robustness of the results across the different models. The sensitivity of the simulated surface ozone to changes in climate between the periods 2000–2009 and 2040–2049 differs by a factor of two between the models, but the general pattern of change with an increase in southern Europe is similar across different models. Emissions of isoprene differ substantially between different CTMs ranging from 1.6 to 8.0 Tg yr−1 for the current climate, partly due to differences in horizontal resolution of meteorological input data. Also the simulated change in total isoprene emissions varies substantially across models explaining part of the different climate response on surface ozone. Ensemble mean changes in summer mean ozone and mean of daily maximum ozone are close to 1 ppb(v) in parts of the land area in southern Europe. Corresponding changes of 95-percentiles of hourly ozone are close to 2 ppb(v) in the same region. In northern Europe ensemble mean for mean and daily maximum show negative changes while there are no negative changes for the higher percentiles indicating that climate impacts on O3 could be especially important in connection with extreme summer events.
Abstract. The impact of climate and emissions changes on the deposition of reactive nitrogen (Nr) over Europe was studied using four offline regional chemistry transport models (CTMs) driven by the same global projection of future climate over the period 2000–2050. Anthropogenic emissions for the years 2005 and 2050 were used for simulations of both present and future periods in order to isolate the impact of climate change, hemispheric boundary conditions and emissions, and to assess the robustness of the result across the different models. The results from these four CTMs clearly show that the main driver of future N-deposition changes is the specified emission change. Under the specified emission scenario for 2050, emissions of oxidised nitrogen were reduced substantially, whereas emissions of NH3 increase to some extent, and these changes are largely reflected in the modelled concentrations and depositions. The lack of sulphur and oxidised nitrogen in the future atmosphere results in a much larger fraction of NHx being present in the form of gaseous ammonia. Predictions for wet and total deposition were broadly consistent, although the three fine-scale models resolve European emission areas and changes better than the hemispheric-scale model. The biggest difference in the models is for predictions of individual N-compounds. One model (EMEP) was used to explore changes in critical loads, also in conjunction with speculative climate-induced increases in NH3 emissions. These calculations suggest that the area of ecosystems which exceed critical loads is reduced from 64% for year 2005 emissions levels to 50% for currently estimated 2050 levels. A possible climate-induced increase in NH3 emissions could worsen the situation, with areas exceeded increasing again to 57% (for a 30% NH3 emission increase).
Abstract Geographic information systems have finally arrived in state and local governments and, with them, an extraordinary opportunity for planning. Many groups with differing agendas are competing to define this new technology, what it will do, and who will use it. It is by no means certain that planners will do well in this competition. This article mines the literature on technological innovation and concludes that planners must understand GIS as a socially constructed technology, including not just hardware and software but also the practices, laws, organizational arrangements, and knowledge that are necessary for its use. The article recommends a strategic approach to GIS implementation that involves both human and technical systems.
Observations of atmospheric reactive nitrogen (Nr) deposition are severely restricted in spatial extent and type. The chain of processes leading to atmospheric deposition emissions, atmospheric dispersion, chemical transformation and eventual loss from the atmosphere is extremely complex and therefore currently, observations can only address part of this chain.
Abstract. Currently residential wood combustion (RWC) is increasing in Europe because of rising fossil fuel prices but also due to climate change mitigation policies. However, especially in small-scale applications, RWC may cause high emissions of particulate matter (PM). Recently we have developed a new high-resolution (7 km × 7 km) anthropogenic carbonaceous aerosol emission inventory for Europe. The inventory indicated that about half of the total PM2.5 emission in Europe is carbonaceous aerosol and identified RWC as the largest organic aerosol (OA) source in Europe. The inventory was partly based on national reported PM emissions. Use of this OA inventory as input for two Chemical Transport Models (CTMs), PMCAMx and EMEP MSC-W, revealed major underestimations of OA in winter time, especially for regions dominated by RWC. Interestingly, this was not universal but appeared to differ by country. In the present study we constructed a new bottom-up emission inventory for RWC accounting for the semi-volatile components of the emissions. The new RWC emissions are higher than those in the previous inventory by a factor of 2–3 but with substantial inter-country variation. The new emission inventory served as input for the CTMs and a substantially improved agreement between measured and predicted organic aerosol was found. The new RWC inventory improves the model calculated OA significantly. Comparisons to Scandinavian source apportionment studies also indicate substantial improvements in the modeled wood-burning component of OA. This suggests that primary organic aerosol emission inventories need to be revised to include the semi-volatile OA that is formed almost instantaneously due to cooling of the flue gas or exhaust. Since RWC is a key source of fine PM in Europe, a major revision of the emission estimates as proposed here is likely to influence source-receptor matrices and modelled source apportionment. Since usage of biofuels, such as wood, in small combustion units is a globally significant source, this insight may also dramatically change global estimates of organic aerosol emissions.
Abstract. The global nitrogen (N) cycle at the beginning of the 21st century has been shown to be strongly influenced by the inputs of reactive nitrogen (Nr) from human activities, including combustion-related NOx, industrial and agricultural N fixation, estimated to be 220 Tg N yr−1 in 2010, which is approximately equal to the sum of biological N fixation in unmanaged terrestrial and marine ecosystems. According to current projections, changes in climate and land use during the 21st century will increase both biological and anthropogenic fixation, bringing the total to approximately 600 Tg N yr−1 by around 2100. The fraction contributed directly by human activities is unlikely to increase substantially if increases in nitrogen use efficiency in agriculture are achieved and control measures on combustion-related emissions implemented. Some N-cycling processes emerge as particularly sensitive to climate change. One of the largest responses to climate in the processing of Nr is the emission to the atmosphere of NH3, which is estimated to increase from 65 Tg N yr−1 in 2008 to 93 Tg N yr−1 in 2100 assuming a change in global surface temperature of 5 °C in the absence of increased anthropogenic activity. With changes in emissions in response to increased demand for animal products the combined effect would be to increase NH3 emissions to 135 Tg N yr−1. Another major change is the effect of climate changes on aerosol composition and specifically the increased sublimation of NH4NO3 close to the ground to form HNO3 and NH3 in a warmer climate, which deposit more rapidly to terrestrial surfaces than aerosols. Inorganic aerosols over the polluted regions especially in Europe and North America were dominated by (NH4)2SO4 in the 1970s to 1980s, and large reductions in emissions of SO2 have removed most of the SO42− from the atmosphere in these regions. Inorganic aerosols from anthropogenic emissions are now dominated by NH4NO3, a volatile aerosol which contributes substantially to PM10 and human health effects globally as well as eutrophication and climate effects. The volatility of NH4NO3 and rapid dry deposition of the vapour phase dissociation products, HNO3 and NH3, is estimated to be reducing the transport distances, deposition footprints and inter-country exchange of Nr in these regions. There have been important policy initiatives on components of the global N cycle. These have been regional or country-based and have delivered substantial reductions of inputs of Nr to sensitive soils, waters and the atmosphere. To date there have been no attempts to develop a global strategy to regulate human inputs to the nitrogen cycle. However, considering the magnitude of global Nr use, potential future increases, and the very large leakage of Nr in many forms to soils, waters and the atmosphere, international action is required. Current legislation will not deliver the scale of reductions globally for recovery from the effects of Nr deposition on sensitive ecosystems, or a decline in N2O emissions to the global atmosphere. Such changes would require substantial improvements in nitrogen use efficiency across the global economy combined with optimization of transport and food consumption patterns. This would allow reductions in Nr use, inputs to the atmosphere and deposition to sensitive ecosystems. Such changes would offer substantial economic and environmental co-benefits which could help motivate the necessary actions.
Engineered glyphosate resistance is the most widely adopted genetically modified trait in agriculture, gaining widespread acceptance by providing a simple robust weed control system. However, extensive and sustained use of glyphosate as a sole weed control mechanism has led to field selection for glyphosate-resistant weeds and has induced significant population shifts to weeds with inherent tolerance to glyphosate. Additional weed control mechanisms that can complement glyphosate-resistant crops are, therefore, urgently needed. 2,4-dichlorophenoxyacetic acid (2,4-D) is an effective low-cost, broad-spectrum herbicide that controls many of the weeds developing resistance to glyphosate. We investigated the substrate preferences of bacterial aryloxyalkanoate dioxygenase enzymes (AADs) that can effectively degrade 2,4-D and have found that some members of this class can act on other widely used herbicides in addition to their activity on 2,4-D. AAD-1 cleaves the aryloxyphenoxypropionate family of grass-active herbicides, and AAD-12 acts on pyridyloxyacetate auxin herbicides such as triclopyr and fluroxypyr. Maize plants transformed with an AAD-1 gene showed robust crop resistance to aryloxyphenoxypropionate herbicides over four generations and were also not injured by 2,4-D applications at any growth stage. Arabidopsis plants expressing AAD-12 were resistant to 2,4-D as well as triclopyr and fluroxypyr, and transgenic soybean plants expressing AAD-12 maintained field resistance to 2,4-D over five generations. These results show that single AAD transgenes can provide simultaneous resistance to a broad repertoire of agronomically important classes of herbicides, including 2,4-D, with utility in both monocot and dicot crops. These transgenes can help preserve the productivity and environmental benefits of herbicide-resistant crops.
Abstract. The Copernicus Atmosphere Monitoring Service (CAMS) delivers a range of full, free and open products in relation to atmospheric composition at global and regional scales. The CAMS Regional Service produces daily forecasts, analyses, and reanalyses of air quality in Europe. This Service relies on a distributed modelling production by eleven teams in ten European countries: CHIMERE (France), DEHM (Denmark), EMEP (Norway), EURAD-IM (Germany), GEM-AQ (Poland), LOTOS-EUROS (The Netherlands), MATCH (Sweden), MINNI (Italy), MOCAGE (France), MONARCH (Spain), SILAM (Finland). The project management and coordination of the service is devoted to a Centralised Regional Production Unit. Each model produces every day 24 h analyses for the previous day and 97 h forecasts for 19 chemical species over a spatial domain at 0.1x01. degree resolution (approximately 10 km x 10 km) with 420 points in latitude and 700 in longitude and 10 vertical levels. Six pollen species are also delivered for the surface forecasts. The eleven individual models are then combined into an ENSEMBLE median. In total, more than 82 billion data points are made available for public use on a daily basis. The design of the system follows clear technical requirements in terms of consistency in the model setup and forcing fields (meteorology, surface anthropogenic emission fluxes, and chemical boundary conditions). But it also benefits from a diversity of in the description of atmospheric processes through the design of the eleven European Chemistry Transport Models (CTM) involved. The present article aims to provide a comprehensive technical documentation, both for the setup as well as for the diversity of CTM involved in the Service. We also include an overview of the main output products, their public dissemination and the related evaluation and quality control strategy.
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