Blown with the wind

摘要

In the lower levels of the atmosphere, ozone is both a greenhouse gas and an air pollutant. Ozone plays a central role in atmospheric chemistry, and is the primary chemical source of the hydroxyl radical, a powerful oxidant that removes most reactive trace gases from the atmosphere~1. Most tropospheric ozone is generated by the photochemical breakdown of precursor compounds, such as methane, carbon monoxide and non-methane volatile organic compounds. In the troposphere, ozone has a lifetime of days to weeks; hence its geographical distribution is highly inhomogeneous. Since the start of the industrial era, levels of ozone precursor compounds — many of which are byproducts of human activities such as biomass and fossil-fuel burning — have grown in the lower atmosphere, leading to a significant increase in surface ozone. This rise in surface ozone concentrations has had an adverse effect on the health of humans as well as terrestrial ecosystems~2 — for example, by damaging leaf structure and reducing crop productivity. Writing in Nature Geoscience, Lin and colleagues show that shifts in atmospheric circulation influence long-term trends in surface ozone concentrations in a given location~3.