Burden of black carbon
Forests: Nature at your Service’—this year’s World Environment Day theme—emphasises the variety of life-sustaining services that forests provide and reminds us to take action to protect these resources. The problem of forests is intrinsically linked to the problem of black carbon. One reason we are losing our forests is that people still have to use fuelwood from forest trees for cooking and heating. These fires are also a major source of the black carbon that scientists now realise is negatively affecting us all in many ways.
Black carbon is found in the tiny particles of soot in smoke and exhaust fumes. It is produced when oil, diesel, and coal are burned in power plants, brick kilns and vehicles, when rubbish is burned and when wood is used for cooking and heating. The black carbon particles can rise into the air and be transported over long distances. In satellite pictures, we see them in the form of a long plume of smoke—an atmospheric brown cloud. The haze obscuring our mountain views also contains these black carbon particles.
Indoors, smoke fills the air and affects peoples’ lungs. Women and children suffer especially from chronic colds, bronchitis, asthma, and lung diseases. Air pollution outdoors, much of it from vehicles, has a similar effect. Heart attacks, cancer, nervous toxicity and premature deaths are also increased.
Outdoors, black carbon has another even more detrimental effect; we now know that black carbon is a big contributor to climate change. Black carbon can rise high up in into the air, and is carried long distances by the wind. When suspended in the air, it absorbs sunlight, warming the air and contributing to the heating of the planet. At the same time, it prevents sunlight from reaching the ground, so the ground is cooler, leading to lower yields of crops and more fog.
Black carbon also increases glacier melting. Usually snow reflects the sun, but when the black particles fall on snow or ice, the dirty snow absorbs sunlight, heating the air above and the snow and ice beneath. Studies indicate that the effect of black carbon on melting of snow and sea ice is three times greater than that of carbon dioxide. Black carbon is thought to be responsible for nearly one third of increased snowmelt. In Nepal, instead of snow-capped mountains in winter, we are now seeing bare rock. Black carbon may also be affecting rainfall patterns and the monsoon in different ways, including reducing normal rainfall and increasing very heavy rainfall.
In Asia, more than a billion people could be affected by the changes in monsoon rainfall and the amount of glacial and snow meltwater feeding the mighty rivers. These effects could have dramatic implications for food security.
Despite these depressing facts, the good news is that with black carbon there is a lot that we can do, and we can do it now—with immediate effect. Asia is thought to produce more than half of all global emissions, and thus has a huge opportunity for combating the negative effects. Black carbon has a much shorter lifespan than carbon dioxide, another major cause of global warming. The particles can be removed from the air in a matter of weeks by the process of ‘settling out’, or in raindrops and snowflakes. If we stop CO2 emissions tomorrow, the effects will only be seen by our grandchildren. But if we reduce the amount of black carbon, the atmospheric warming effects would disappear within weeks and the change would be clearly visible within a decade.
Since one of the main sources of black carbon emissions in developing countries is the use of open fires for cooking, this is one area where we can make substantial changes. In Nepal, 80 per cent of households use fuelwood for cooking. Improved stoves that use much less wood and produce much less smoke cost less than US $4 each. These stoves improve indoor air quality, save the effort of collecting fuelwood, and spare the forests. The Government of Nepal is also promoting renewable energy through biogas (an even more efficient way of reducing the use of wood), solar lighting, and micro-hydro programmes, all of which can help in reducing black carbon.
There are other important areas. One is reducing emissions from diesel engines, and discouraging the use of diesel fuel. Similarly, brick kilns send out large amounts of black smoke. Investment in the appropriate emission-reducing technology would significantly reduce black carbon. Another is reducing smoke from forest fires.
In 2010, there were more than 300 forest fires in Nepal, and large amounts of black carbon were deposited in the Khumbhu region, near Everest. Many forest fires result from people’s activities and forest burning policies—changes to these practices, as well as improved methods to combat fires—would be of great help.
Today, countries like Nepal offer the lowest cost option for programmes to reduce black carbon. Such programmes would have many benefits: improved air quality, reduction in health issues, a positive impact on climate change and, not least, the preservation of forests. With strong political will and minimal investment, it is possible to make a large difference.
In 2001, the International Centre for Integrated Mountain Development (ICIMOD) began a study in conjunction with The United Nations Environmental Programme (UNEP) on atmospheric brown clouds in the Himalayan
region. This ‘brown cloud’ is a layer of pollution containing black carbon soot and dust, and the study is part of a wider one being conducted across Asia.
On World Environment Day, we must highlight the need to collect and share data and information on black carbon, to work towards developing a common approach and support coordination of efforts at both the national and regional levels.
Pradhan is Environment Officer at ICIMOD
Posted on: 2011-06-05 09:11
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