Nordic pine forests – the new pollutants

A new pollutant has been identified which will sit uncomfortably on the usual list of cars, planes and industry: coniferous Nordic forests.

According to environmental experts at Stockholm University, the pines and spruces of northern Europe create masses of small particles which drift up to 1,000 metres into the atmosphere.

The trees emit a substance, known as terpenes, which are responsible for their distinctive aroma, says Hans-Christen Hansson at Stockholm University’s Department of Applied Environmental Science.

In the latest edition of Science, Hansen and his colleagues describe how these terpenes can develop into tiny particles, which in turn have the potential to influence the climate.

“In the coniferous forests of northern Europe, there are enormous amounts of terpenes, especially in the summer. The levels vary according to the temperature and the amount of sunlight,” Hansson told Svenska Dagbladet.

This kind of particle has not been identified before, but Hansson says the phenomenon is not confined to Nordic forests.

“Up to 1.4 billion tonnes of these natural, organic compounds are produced each year in the world,” he said.

A single tree can produce 1,000 to 2,000 particles per cubic centimetre of air.

While Hansson emphasised to SvD that the particles “undoubtedly affect the climate” he pointed out that the pollutant levels were somewhat lower than city centres, for example.

“The levels in Stockholm city centre are 100-200 micrograms per cubic metre, compared to 4-5 in our forest measurements.”

Louis Roper