Climate changes spread of air pollution

In an altered future climate, air pollutants could become more long lasting. The concentration of pollutants in the atmosphere is increasing and the way they spread will also change - something that could render current approaches to reducing emissions obsolete.

Future climate changes will entail that air pollution in primarily Southern Europe increases, while Scandinavia could see greater fallout of acid and eutrophicating substances. International agreements to limit emissions of pollutive substances could be rendered ineffective. This is a possible scenario envisioned in a new report from SMHI.

"I think we can see this as a wake-up call. Obviously it´s important to be careful when making statements about the future, but other studies also point in the same direction," says Magnuz Engardt, an air environment researcher at SMHI.

The report, entitled Luftföroreningar i Europa under framtida klimat (Air Pollution in Europe in Future Climate Conditions), is based on calculations made partly in SMHI´s advanced chemistry and transport model MATCH, and partly in the RCA3 regional climate model at the Rossby Center, SMHI´s climate research unit. MATCH provides a description of how air pollutants spread and are converted in the atmosphere. RCA3 describes future climate changes in Europe.

With a drier, warmer climate in Central and Southern Europe and a damper climate in Northern Europe, air pollution will spread differently than it does at present. Ozone concentrations are expected to increase sharply by 1-2% per decade up to 2050 in Central and Southern Europe, primarily during the summer. The maximum concentrations will increase more than the mean concentrations.

Similarly, the calculations show that Central and Southern Europe will also be affected by dramatic rises in particle concentration: some 3-5% per decade up to 2050.

Scandinavia will experience only minor changes in ozone and particle concentrations. As precipitation will decrease in Central and Southern Europe, less sulphur and nitrogen pollutants will be washed away by rain on the Continent. Instead some of the fallout will affect Scandinavia, which will therefore experience greater acidification. However, this will only affect a limited area, mainly the Norwegian coast.

In a way, the climate changes will work against efforts being made to reduce air pollution. The study indicates that air pollutants will last longer and their concentration in the atmosphere will therefore increase. This also applies to the substances that form ozone: nitrogen oxides and hydrocarbons.

"If you look at the 1999 Gothenburg Protocol on air pollution, the key is to reduce emissions in Europe where it will do the most good and is most cost effective. For example, it´s more effective for the European environment to take action at a factory in Germany than in Iceland," Magnuz Engardt explains.