Friday, 02 October 2009 12:25

Black Carbon: A short-lived climate-forcing agent

As the climate in the Arctic changes and the Greenlandic Ice sheet and sea ice melts at a more rapid rate and scale than expected mean model projections, the Ministers of the Arctic Council member states have established a task force on short-lived climate-forcing agents (SLCF’s) in a meeting in Tromsø in April, 2009. The mandate from the Tromsø Declaration reads:

“Decide to establish a task force on short-lived climate forcers to identify existing and new measures to reduce emissions of these forcers and recommend further immediate actions that can be taken and to report on progress at the next Ministerial meeting”

Photo: www.polaret.no

Black Carbon is one of the short-lived climate forcing agents (tropospheric ozone and methane are SLCF’s too). Black Carbon is an air pollutant composed of very fine particles of carbon that can be released into the air in aerosol form. Black Carbon is created by the incomplete combustion of fossil fuels (diesel and coal particularly), bio-fuels, and biomass. Carbon dioxide (CO2), on the other hand is the most well-known greenhouse gas, but is not as such a toxic substance. In fact, plants utilize CO2 in the photosynthesis. The problem with CO2 is its accumulation in the atmosphere and its ways of heating it up.

When Black Carbon from the atmosphere in Arctic areas is deposited on ice and snow it makes the ice and snow packs darker, reducing the Albedo effect (the ability to reflect sunlight). The effect it has on snow covered sea ice is much more pronounced because as the snow melts, the Black Carbon accumulates on the ice surface in high concentrations. That makes snow and ice absorb more heat and thereby accelerates melting in summer months, which is the kind of feedback loop that practically defines the climate change problem.

Black Carbon has another characteristic which has drawn attention in the climate change debate. While CO2 has a life of up to about 40 years in the atmosphere, Black Carbon remains in the atmosphere for a matter of weeks.

Black Carbon is considered responsible for having an important impact of the Arctic melting. Due to Black Carbons short life, it is expected that emission reductions can rapidly reduce the rate at which Arctic ice is melting and therefore presents a unique opportunity to have an immediate impact on climate change.

Debates are taking place in the international forums on the benefits of respectively reducing the emissions of Black Carbon and mitigating CO2 emission. Black Carbon reductions have more certain and immediate benefits, while reductions in CO2 emissions through CO2 mitigation will probably also have positive effects on climate change however it will only be realized over the longer term. However action on Black Carbon is not seen as an alternative to action on CO2.

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Arctic Council Indigenous Peoples' Secretariat
Fram Centre, Postboks 6606 Langnes, NO-9296 Tromsø, Norway