Emissions of short-lived pollutants like black carbon can be reduced and provide quick reductions in climate change and improvements in air quality. The Ecologist reports
Black carbon – which gives soot its black colouring – is the result of incomplete fossil fuel and wood combustion and is emitted as particles into the atmosphere. The main sources being diesel vehicles and in less industrialised countries from the burning of biomass.
Up in the atmosphere it absorbs sunlight and increases air temperature, while on the ground it adds to air pollution, particularly in urban areas. It can also darken snow and ice, increasing absorption of sunlight and has been linked to accelerating melting of the Arctic.
The contribution of black carbon to warming is thought to be 100-2000 times greater than CO2. However, it has a much shorter lifetime, staying in the atmosphere for only a number of days or weeks compared to 100 years for carbon dioxide (CO2), meaning benefits from reducing emissions will be rapidly noticeable.
In a study this week, the UN Environment Programme (UNEP) estimate we could quickly reduce ‘near-term’ global warming by 0.5 degrees Celsius by tackling black carbon emissions. Reduction measures would have an even greater benefit in the Arctic where it could reduce warming by 0.7 degrees.
This represents as much as two-thirds of change anticipated in sensitive Arctic regions and could help to stem irreversible changes including melting of ice and release of methane from permafrost.
A small number of measures to reduce emissions, including particle filters on diesel vehicles and methane capture from waste management, were identified that would produce immediate benefits.
The report was released at the latest UN climate change meeting in Bonn, Germany, where delegates met to discuss strategies for tackling climate change ahead of the next major UN climate conference (COP 17) in Durban, South Africa, this November.
A reduction of 0.5 degrees could prove vital for nations who agreed to limit global warming to two degrees at last years UN climate summit in Cancun, Mexico, and may lead nations to agree to a more ambitious 1.5 degree limit in the future.