Ozone risk for crops and pastures in present and future climates |
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Authors: | Jürg Fuhrer |
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Institution: | (1) Air Pollution/Climate Group, Agroscope Research Station ART, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland |
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Abstract: | Ozone is the most important regional-scale air pollutant causing risks for vegetation and human health in many parts of the
world. Ozone impacts on yield and quality of crops and pastures depend on precursor emissions, atmospheric transport and leaf
uptake and on the plant’s biochemical defence capacity, all of which are influenced by changing climatic conditions, increasing
atmospheric CO2 and altered emission patterns. In this article, recent findings about ozone effects under current conditions and trends in
regional ozone levels and in climatic factors affecting the plant’s sensitivity to ozone are reviewed in order to assess implications
of these developments for future regional ozone risks. Based on pessimistic IPCC emission scenarios for many cropland regions
elevated mean ozone levels in surface air are projected for 2050 and beyond as a result of both increasing emissions and positive
effects of climate change on ozone formation and higher cumulative ozone exposure during an extended growing season resulting
from increasing length and frequency of ozone episodes. At the same time, crop sensitivity may decline in areas where warming
is accompanied by drying, such as southern and central Europe, in contrast to areas at higher latitudes where rapid warming
is projected to occur in the absence of declining air and soil moisture. In regions with rapid industrialisation and population
growth and with little regulatory action, ozone risks are projected to increase most dramatically, thus causing negative impacts
major staple crops such as rice and wheat and, consequently, on food security. Crop improvement may be a way to increase crop
cross-tolerance to co-occurring stresses from heat, drought and ozone. However, the review reveals that besides uncertainties
in climate projections, parameters in models for ozone risk assessment are also uncertain and model improvements are necessary
to better define specific targets for crop improvements, to identify regions most at risk from ozone in a future climate and
to set robust effect-based ozone standards. |
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Keywords: | Ozone Crops Pastures Climate change Yield loss |
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