Arctic Haze if one of the main effects of Long range
aerosols in the atmosphere. 90% of
haze consists of sulphate and nitrate particles and the reaming consists of
black carbon and hydrocarbons. What really interests me is the warming effects
caused by black carbon (or soot) in the Arctic region. Black carbon sits at the
other end of the spectrum to reflective aerosols (such as sulphates), absorbing
solar radiation and warming the surface temperatures.
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| The picture shows the impacts black carbon (and other aerosols) can cause on limestone buildings. |
BC is caused by the incomplete combustion of organic matter
(including either organic matter, from forest fires, or anthropogenic, as a
result of fossil fuel combustion) and consists of 5-10%
of particulate matter found within urban areas in the US and Europe. Across the
globe, black carbon can have detrimental impacts on local climate and health. This
is particularly an issue in Venice
where buildings are falling victim to the deposition of black carbon.
Warming, caused by black carbon, is particularly profound in
the Arctic region due to the sensitivity of feedback systems which occurring
there. Black carbon, within Arctic haze, absorbs incoming infra-red and converts this to ultra violet radiation, resulting in warming. Deposition of BC also reduces albedo (lowering the ability of the snow covered surface to reflect) and absorbs radiation (directly on the surface) therefore creating localized warming. Such reduction in
albedo can have similar
climatic effects as GHGs, in terms of summer sea ice reduction. Highwood
and Kinnersley (2006) challenge this by stating the direct forcing of
aerosols could make changes of 0.5Wm-2, which only accounts for approximately
1/3 of the warming caused by carbon dioxide and other greenhouse gases. The degree of warming is still uncertain but it is certain that BC is contributing to climate change.
Other, indirect impacts of BC can alter the properties of clouds. When combined with sulphates, in the atmosphere, black carbon can also influence the size of water droplets in clouds.
Furthermore, black carbon particulates can pose as carriers for other toxins. There surface area (of carbon particulates) provide an area for other chemicals, such as polycyclic aromatic hydro carbons, to rest upon and be transported into the lungs. Koelmans et al (2006) argues the presence of BC may be positive. Their paper states the presence of this particulate can make toxic chemicals (on the surface of BC) less available for biota. So maybe it isn’t all bad! However both black carbon and the chemicals transported on its surface, can have serious health implications for humans and other mammals in the region.
So remember, whilst you are sat in front of your roaring
fire this Christmas, the black carbon produced could be causing the Arctic to
melt… Leave a comment with your thoughts!
Although black carbon has an impact on arctic ice, you also mentioned that it can increase water droplet size. Does this mean it could also increase albedo by promoting more cloud cover?
ReplyDeleteHi Louis! Yes i did, the combination of Black Carbon and other Aerosols, such as sulphates can increase water droplets size in clouds, thus increasing the albedo. However I only touched upon this in my blog as in this actually has a very minimal influence on the overall climate as clouds are often covering a very reflective surface anyway.
DeleteTwo thoughts come to my mind Charlie!
ReplyDelete1st off I was thinking thank goodness we've cleaned up our act to such an extent in the UK - I'm sure you've seen pictures of your hometown Bath back in the day, the limestone buildings turned black from their constant covering with soot from various different sources! When they're cleaned now they do tend to stay bright and white for quite a long time!
Secondly, this made me think of a period of when I lived in Kolkata - a city which hasn't cleaned its act up. Kolkata is the 'lung disease capital of India' (70% of Kolkatans struggle with at least one respiratory disease), I lived right in the centre of the city and the levels of soot and black carbon matter settling on everything was really shocking. The 5 minute walk back from school would be enough to turn a white shirt grey if it was raining and at least the collar near black if it wasn’t raining, after just a day of walking around. I remember laying down in a park one day in long grass to read a book, when I got up my arms were black from the soot… Or cleaning, where I lived, I’d have to dust every few days the soot from surfaces despite keeping the windows shut whenever possible. The situation is improving but it needs to be happening faster - for the reasons you raise in terms of ice cap melt back. As well as these shocking rates of respiratory disease for residents of cities such as Kolkata and other major asian cities such as Delhi and Beijing.
Thanks for your comment Rob! Wow how interesting! Yes this is an issue all around the world not just in the Arctic! In an ideal situation Black Carbon would be Incorporated in many clean air policies which would be a 'Win-Win' situation for both climate and peoples health in areas such as Kolkata!
DeleteIf you are interested in the issue of black carbon in India there is an abundance of literature on the topic. This one jumped out to me! Have a read. http://onlinelibrary.wiley.com/doi/10.1029/2002GL015662/full
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