Environmental Impact of Asian Brown Cloud
Asian Haze Has Regional and Global Environmental Consequences
Dec 1, 2008
A report published by the United Nations Environmental Programme (UNEP) entitled “Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia” in November 2008 highlights the global environmental, health and agricultural dangers associated with what has become a permanent atmospheric Asian haze, otherwise known as the Asian brown cloud.
What is the Asian Brown Cloud?
- The Asian atmospheric brown cloud first came to prominence when scientists from the U.S., India and Europe published the findings of the “Indian Ocean Experiment” (INDOEX) in the December 2001 issue of the journal Science.
- Its existence was further confirmed by NASA in a press release, numbered 04-397, issued on December 15, 2004 which stated “NASA scientists announced a giant, smoggy atmospheric brown cloud, which forms over South Asia and the Indian Ocean, and has intercontinental reach.”
- The UNEP 2008 report says that atmospheric brown clouds “start as indoor and outdoor air pollution consisting of particles (referred to as primary aerosols) and pollutant gases, such as nitrogen oxides (NOx), carbon monoxide (CO), sulphur dioxide (SO2), ammonia (NH3), and hundreds of organic gases and acids.”
- Both the UNEP report and the Science article on INDOEX put the cause of the brown cloud on the area’s high population density, incomplete burning of fossil fuels and biofuels, biomass burning for home heating and the unrestricted “slash and burn” method of deforestation.
The report makes clear that atmospheric brown clouds (ABCs) interfere with the environment in a number of ways.
- ABCs interfere with the distribution of the energy of the sun between the surface of the planet and the atmosphere. This can influence both the biosphere and the climate in a fundamental way.
- ABCs produce atmospheric solar heating and surface dimming over Asia in general and China and India in particular.
- ABCs are masking global warming by reducing surface temperatures by as much as 2 degrees Celsius.
- Cities such as Beijing, Dhaka, Kolkata, Bangkok, Karachi, Mumbai, Seoul, New Delhi, Shanghai and Shenzhen have all experienced significant dimming as a results of atmospheric brown clouds.
The Himalayan glaciers provide the source of many of Asia’s great rivers, with millions of people depending on them for food and water. Because ABCs increase atmospheric heating these glaciers are in retreat for the past number of decades. ABCs carry large amounts of soot and black carbon which are deposited on the glaciers, allowing them to absorb more of the sun’s heat and melt quicker.
ABC impact on Agriculture
Dimming induced by atmospheric brown clouds is considered the major cause of the changing pattern of rainfall in Asia, with decreasing rainfall in some parts while other parts experience intense floods. ABCs are interfering with centuries old monsoon patterns with disastrous consequences for food production. The large concentration of ozone in atmospheric brown clouds could decrease crop yields by as much as 20%.
Health Effects of Asian Brown Cloud
According to the UNEP report a large part of the aerosol particulars that make up atmospheric brown clouds are the result of incomplete combustion of fossil fuels and biofuels. The health impact of these particles is an increase in cardiovascular effects, pulmonary illnesses and chronic respiratory problems. The report estimates that in India and China alone, ABCs result in over 330,000 excess deaths per year.
The Asian atmospheric brown cloud has serious health, food and global environmental impacts. As the UNEP report makes clear, since the ABC has a global cooling effect on the environment, removing the problem of the brown cloud without simultaneously lowering greenhouse gas emissions could have a disastrous effect on the planet’s environment.
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