Brussels, 31 Oct 2002

A team of European and international scientists led by the Max Planck Institute for chemistry has discovered evidence of remarkably high pollution levels over the Mediterranean Sea.

The researchers believe that the presence of high levels of aerosols, namely sulphate and soot particles, in the troposphere above the Mediterranean will suppress evaporation levels, and reduce the amount of rainfall in the Middle East and North Africa.

Members of the Mediterranean intensive oxidant study (MINOS) used measurements from research flights and a ground-station in Crete to analyse the pollution levels of the troposphere over the sea. The troposphere is the layer of earth's atmosphere that goes from the surface to an altitude of around 11 to 15 kilometres, and is where weather conditions exist and cloud formation takes place.

The study measured atmospheric conditions over a six week period in the summer of 2001. The greatest amount of pollution was discovered in the lower four kilometres and originated from industrial activity, traffic, forest fires, agriculture and domestic burning in eastern and western Europe. It is these types of pollution that are primarily responsible for the proliferation of microscopic aerosol particles.

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At higher altitudes, results suggested a significant proportion of the pollution present had come from North America and Asia. Such pollution is either transported by prevailing westerly winds, or by the easterly tropical jet stream.

The positive news is that aerosol concentrations today are far lower that two decades ago, due to measures designed to curb acidification of the atmosphere. It is likely, therefore, that the climatic effects of aerosol pollution are decreasing.

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