The sky darkens except in Europe

2009/05/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Ekologia
• Ingurumena

Air pollution has grown since 1973 on all populated continents except Europe. This has been deduced by scientists from the universities of Maryland and Texas, taking into account the level of visibility measured since 3,250 weather stations worldwide.

The level of visibility of the sky has decreased from 1973 to 2007. The biggest darkening has occurred in South Africa and South America. In this darkening aerosols have been important, but the main responsible have been soot particles and sulphates produced by burning fossil fuels. Only in Europe has heaven been cleansed in the last thirty years. This research contradicts two others published in the journal Science in 2005. It was concluded that between 1950 and 1990 the heavens were darkened, but that from 1990 onwards they were to be illuminated worldwide.

Scientists believe that air pollution is not only about health, but also about climate change, although they don't know exactly how. On the one hand, soot and aerosols can cause increased mists and cool the atmosphere because these mists reflect solar rays into space. However, aerosols sometimes decrease mists, as is believed to have occurred in northern China. In addition, biofuel soot absorbs sunlight instead of reflecting it into space. This would cause warming of the troposphere as much as carbon dioxide and other greenhouse gases. Therefore, scientists cannot determine the effect of air pollution at global temperature.