Headline:
Climate Change Could Lead to More High-Ozone Events in Central Europe
In large parts of Central Europe, extreme ozone events frequently concur with higher temperatures. Under future climate change, with heatwaves forecast to become stronger and more frequent, it is likely that these areas will experience more high ozone events. Other parts of Europe could be much less affected. This is the conclusion of a study now published in the journal “Environmental Research Letters” that investigates the effect of meteorological variables on ground-level ozone in Europe during the “ozone seasons” of spring and summer. Elevated concentrations of ground-level ozone damage vegetation and ecosystems, and are detrimental to public health.
“It has been established that there is a strong relationship between ground-level ozone and meteorology, however a better understanding about the effects of a changing climate on ozone air quality is needed. The topic is attracting interest not only in the scientific community but also in the general population because ground-level exposure has been associated with cardiovascular and respiratory problems, causing premature deaths,” explained lead author Noelia Otero Felipe of the IASS.
Ground-level or tropospheric ozone is a secondary pollutant not emitted directly. It forms in the troposphere by catalytic photochemical reactions of nitrogen oxides with carbon monoxide, methane, and other volatile organic compounds. Significant sources of these ozone precursors are traffic and industry, but also plants and soil. Ozone belongs to the so-called short-lived climate-forcing pollutants (SLCPs), which have a relative short lifetime in the atmosphere, from a few days to a few decades. Moreover, ground-level ozone formation has been related to meteorological parameters, which implies that changes in meteorological conditions would lead to changes in ozone pollution episodes. Therefore, all these changes indirectly increase human health risks associated with higher pollutant levels. The researchers attempted to identify the main drivers of high ozone values and to determine regional and seasonal variations of those drivers.
Using statistical modelling, their study assesses the influence on surface ozone of several local meteorological parameters, such as maximum temperature, relative humidity, solar radiation, and wind speed but also takes the influence of atmospheric circulation on a larger scale into account. To assess the spatial variability of observed effects, the researchers divided the continent into a grid of 100x100 km squares. They used meteorological data measured in these grid cells in the spring and summer seasons in the period from 1998 through to 2012. They then applied three different statistical techniques; namely, multiple linear regression, quantile regression and logistic regression, to assess the influence of the parameters on different ozone concentrations (mean values and extremes).
The results suggest that a warmer climate in some regions would adversely affect ozone levels and, consequently, air quality. Maximum temperature plays an important role in summertime in Central Europe, while it has a lesser effect in South Europe. “The link between temperature and ozone pollution has been known for some time already, but this is the first study to examine the way the strength of this link varies between different regions, so this is really a new insight,” commented Tim Butler, co-author and leader of the programme Air Quality in the Context of Global Change at the IASS. He stressed that existing laws and regulations are not sufficient to bring about a lasting reduction in ozone concentrations that would sufficiently protect the population from its harmful effects.