title: Current and future ozone risks to global terrestrial biodiversity and ecosystem processes.
abstract: Risks associated with exposure of individual plant species to ozone (O3) are well documented, but implications for terrestrial biodiversity and ecosystem processes have received insufficient attention. This is an important gap because feedbacks to the atmosphere may change as future O3levels increase or decrease, depending on air quality and climate policies. Global simulation of O3using the Community Earth System Model (CESM) revealed that in 2000, about 40% of the Global 200 terrestrial ecoregions (ER) were exposed to O3above thresholds for ecological risks, with highest exposures in North America and Southern Europe, where there is field evidence of adverse effects of O3, and in central Asia. Experimental studies show that O3can adversely affect the growth and flowering of plants and alter species composition and richness, although some communities can be resilient. Additional effects include changes in water flux regulation, pollination efficiency, and plant pathogen development. Recent research is unraveling a range of effects belowground, including changes in soil invertebrates, plant litter quantity and quality, decomposition, and nutrient cycling and carbon pools. Changes are likely slow and may take decades to become detectable. CESM simulations for 2050 show that O3exposure under emission scenario RCP8.5 increases in all major biomes and that policies represented in scenario RCP4.5 do not lead to a general reduction in O3risks; rather, 50% of ERs still show an increase in exposure. Although a conceptual model is lacking to extrapolate documented effects to ERs with limited or no local information, and there is uncertainty about interactions with nitrogen input and climate change, the analysis suggests that in many ERs, O3risks will persist for biodiversity at different trophic levels, and for a range of ecosystem processes and feedbacks, which deserves more attention when assessing ecological implications of future atmospheric pollution and climate change.
authors.affiliation: Agroscope Climate/Air Pollution Group Zurich Switzerland.
authors.forename: Jürg
authors.initials: J
authors.lastname: Fuhrer
authors.affiliation: Department of Chemical and Biological Engineering University of Sheffield Sheffield UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Val Martin
authors.affiliation: Centre for Ecology and Hydrology Environment Centre Wales Bangor Gwynedd UK.
authors.forename: Gina
authors.initials: G
authors.lastname: Mills
authors.affiliation: Department of Civil and Environmental Engineering and Department of Earth, Atmospheric and Planetary Sciences Massachusetts Institute of Technology Cambridge MA USA.
authors.forename: Colette L
authors.initials: CL
authors.lastname: Heald
authors.affiliation: Centre for Ecology and Hydrology Environment Centre Wales Bangor Gwynedd UK.
authors.forename: Harry
authors.initials: H
authors.lastname: Harmens
authors.affiliation: Centre for Ecology and Hydrology Environment Centre Wales Bangor Gwynedd UK.
authors.forename: Felicity
authors.initials: F
authors.lastname: Hayes
authors.affiliation: Centre for Ecology and Hydrology Environment Centre Wales Bangor Gwynedd UK.
authors.forename: Katrina
authors.initials: K
authors.lastname: Sharps
authors.affiliation: Institute of Biodiversity Thünen Institute Braunschweig Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bender
authors.affiliation: Stockholm Environment Institute University of York York UK.
authors.forename: Mike R
authors.initials: MR
authors.lastname: Ashmore
keywords: Community Earth System Model; G200 ecoregions; air pollution; atmospheric feedback; global climate change; species diversity