Acid rain kills wildlife, erodes buildings and turns lakes into dark lifeless bodies of water. It is created in industrial heartlands and affects great swathes of the planet. Nowhere is it more destructive than in lakes and forests in Scandinavia. In winter the jet stream blows from east to west around northern Europe and at times it narrows to become a very efficient carrier of pollutants. While Europe’s industrial core has done much to alleviate pollution in its locality by building ever taller chimneys, this has only served to spread toxic gases further. Coal-fired power stations are the biggest culprits. They release sulphur dioxide molecules into the atmosphere, which then mix with naturally occurring particles to produce acid rain.
Even small amounts of pollutants can upset delicate ecosystems. Very low concentrations can cause PH levels to fall below 5, when fish eggs will not hatch and insect larvae will not develop, removing a vital part of the food chain. This has the knock-on effect of depriving birds and mammals of much of their diet. Acid rain not only affects areas where it falls directly, but can also be carried through large river systems into bodies of water several miles away.
The effects can be seen most markedly when travelling through Finland, where lake after lake has an eerie mirror-like appearance, providing a perfect reflection of the surrounding forested hills. Gas desulphurization at the source of the pollution has done something to alleviate the problem, but it will take generations for the Scandinavian countryside to recover. It is a sad irony that Scandinavians are pioneers in green living – but they can do little to prevent the drift of rain across their borders.
When: 1950s onwards
Where: Scandinavia, North America, China and Russia
Toll: As well as the devastating effect on wildlife, the particles associated with acid rain have been linked to several forms of cancer and respiratory diseases.
You should know: International agreement is the only way forward. The European Union has vowed to reduce emissions that cause acid rain by 60 per cent within the next decade. While acid rain can be caused by naturally occurring phenomena such as volcanic eruptions, it is only by limiting our own emissions that the lakes of Scandinavia can be restored to their former vibrancy.