Threats from air pollution and climate change to upland systems: Past, present and future
The impacts of air pollution on ecosystems were probably most widespread in the nineteenth and early twentieth centuries in newly industrialising countries where coal-burning, smelting and other activities released large amounts of pollutants, including sulphur and various metals (e.g. lead, copper, zinc, iron), into their local environments. Problems caused by large emissions of pollutants of heavy industry have diminished in recent decades in much of Western Europe and North America where sulphur emissions have declined and been dispersed over a wider area away from point sources. The drop in emissions in regions such as Western Europe contrasts with the steep rise now seen in many developing countries. While pollutants of traditional heavy industry are now more important in rapidly developing nations, but less so in developed countries, the pollutants created largely by motor vehicles and intensive use of fertilisers in farming (nitrogen, ozone and hydrocarbons) are increasing or remain high in practically all populated world regions (Bell and Treshow, 2002).