Until recently concerns about our climate focused entirely on emissions of greenhouse gases such as carbon dioxide and methane. These gases remain in the atmosphere for many years after they are released, where they have a warming effect.
There are, however, another class of emissions which have an impact on our climate. These are substances with a short life of only days or weeks in our atmosphere such as black carbon and ground level ozone. Concerns are growing around these short lived substances: a recent United Nations Environment Programme report concluding that 20-25% of the man-made warming we are experiencing is down to this group of substances.
Black carbon affects the climate in three ways.
- As black carbon is dark it absorbs heat from the sun and warms its immediate environment – the ‘direct effect’;
- Black carbon falling onto snow and ice reduces the amount of heat reflected and can cause melting –the ‘albedo effect’; and
- Black carbon in the air can also interfere with clouds and rainfall patterns – the ‘indirect effect’
In addition to its impacts on climate, black carbon also has a direct impact on our health. Tiny particles of black carbon contribute to the amount of ‘particulate matter’ in the air. Particulate matter is thought to be responsible for up to 200,000 premature deaths annually in the UK. You can find out more about air pollution and health at our Healthy Air website
