Atmospheric brown clouds are persistent, moving air masses, found high in the atmosphere, largely made up of soot, chemicals, aerosols and unhealthy gases such as ozone. The United Nations reports that brown clouds are the newest, and one of the greatest threats, to our global environment, especially to the worldwide food supply. Brown clouds are caused by man-made pollutants, mainly fossil fuels such as coal. Controlled burning of wood and plants also contributes to the formation of brown clouds. Once formed, atmospheric brown clouds increase the amount of greenhouses gases in the air, especially in industrialized countries.
Brown clouds as seen from space are a worldwide problem. Individual cloud masses can move across entire continents in as little as two days. Cloud hot spots have been identified over North and South America, Europe, South Africa and the largest brown cloud is currently laying over Asia. The region from the Persian Gulf extending through much of Asia is covered with a brown cloud annually from November through April due to lack of monsoon rains to wash the pollutants out of the air. The brown cloud currently hanging over this region has caused a 25% reduction in sunlight. This effects crop production and helps to create the extreme weather conditions that have been witnessed in this part of the world in recent years.
Studies have shown that brown clouds contribute to glacial melting. The Himalayan Glaciers which are the primary source of water for rivers throughout many parts of Asia have shrunk by five percent in the past 50 years and scientists think the glaciers could shrink another 70% in the next 50 years. While there is no doubt that brown cloud pollution is contributing to glacial melting it is sometimes difficult to see the full impact of damage caused by brown clouds because these dense clouds help cool the earth’s surface temperatures in some areas of the world because the pollution particles found inside of these toxic clouds reflect sunlight and cool down the air.
Brown clouds not only have a negative effect on crop production and the environment but also on peoples’ health. Over two million people die in India each year from cardiovascular and respiratory diseases. “All of this points to an even greater and urgent need to look at emissions across the planet because this is where the stories are linked in terms of greenhouse emissions and particle emissions and the impact that they’re having on our global climate,” said Achim Steiner, U.N. undersecretary general and executive director of the U.N. environment program.