I flew from London Gatwick to Madrid in the afternoon of the 7th of April 2011. The atmosphere over Spain was thick with a brown yellow dust. It was not possible to see the ground flying a 10,000 meters above sea level in an Airbus 320.
When flying over the Sierra de Guadarrama, a chain of mountains up to 2,500 high feeding Madrid city with water, the tip of the highest peaks were barely guessed from the thick surronding air.
This is global dimming on a gigantic scale. Western Europe sends plumes of pollutant particles to the Sahel in the last decades. This results in droughts and climate change in the Sahel. Exposed soils are fragile and 60 to 200 million tons of dust travel in huge clouds to the rest of the planet. The Canary Islands and the Caribbean are the most affected regions. The Atlantic gets richer with iron, nitrogen and phosphate materials that result in massive booms of phytoplankton. These outbreaks are common in spring and summer and increasingly frequent over the last years.
Isabel Reche of the Universidad de Granada lead a research to to assess the role of aerosols as a long-range vehicle of microorganisms and their colonizing ability. A NASA team composed William Lau and Kyu-Myong Kim claimed that more than one-third of the drop in North Atlantic sea surface temperatures between June 2005 and 2006 was due to the Saharan dust blocking the radiation of the Sun. This could have contributed to the formation of less hurricanes in 2006.