There are several types of long range pollutants the Arctic
including: Mercury, PCBs and Toxaphene. Aerosols, in particular
sulphates, are also very dominant in the region. Many of these
aerosols, are generated by smelting and mining, within the Russian
Arctic, generating large amounts of pollutants, which have been
transported to remote regions. Industrialization isn't the only
source tough! Another, more common source of aerosols can be found
within your deodorant cans…
Now, I was asked recently asked how I would define an aerosol and
honestly I couldn’t! So before I get into the depths of the
influence of aerosols on cloud properties (the topic of my next
post!) I thought I would take a step back and explain what an aerosol
is.
An
aerosol is defined as a gas containing suspended solid
particulates. These can occur in either man-made or natural forms
(due to the nature of man-made aerosols they will be the focus). 90% of aerosols are occur naturally including volcanoes, dust and even sea salt; yet it is the remaining 10% which I am interested in. These aerosols can have direct
(reflect or absorb sunlight) and indirect (modify cloud properties) to
alter the earth's energy budget. Examples of these harmful man-made
aerosols can include CFCs, Black Carbon, Nitrates and sulphates and are often found to dominate downwind of urban or industrial regions.
Aerosols can cause a range of direct and indirect effects. A direct effect refers to the influence aerosols have on climate by reflecting or absorbing radiation. Aerosols can have both direct warming and cooling effects dependent on the composition and colour. Broadly speaking lighter and translucent aerosols (such as sulphates and nitrates) reflect solar radiation back into space causing cooling, and darker particles (for example black carbon) absorb radiation and cause warming. "scientists believe the cooling from sulphates and other reflective aerosols overwhelms the warming effects of black carbon and other absorbing aerosols on the planet". This has been taken as far as stating aerosols have counteracted about half the warming caused by green house gases since emissions began in the 1800s. However in the Arctic these warming aerosols have a more prominent impact. Indirect effects (which will be discussed in my next blog post so stick tight!) alter the the size of cloud particles, consequently changing the total amount of radiation reflected and absorbed.
Aerosols can cause a range of direct and indirect effects. A direct effect refers to the influence aerosols have on climate by reflecting or absorbing radiation. Aerosols can have both direct warming and cooling effects dependent on the composition and colour. Broadly speaking lighter and translucent aerosols (such as sulphates and nitrates) reflect solar radiation back into space causing cooling, and darker particles (for example black carbon) absorb radiation and cause warming. "scientists believe the cooling from sulphates and other reflective aerosols overwhelms the warming effects of black carbon and other absorbing aerosols on the planet". This has been taken as far as stating aerosols have counteracted about half the warming caused by green house gases since emissions began in the 1800s. However in the Arctic these warming aerosols have a more prominent impact. Indirect effects (which will be discussed in my next blog post so stick tight!) alter the the size of cloud particles, consequently changing the total amount of radiation reflected and absorbed.
So now you know what an aerosol is you are completely prepared for
next week’s blog! I know leave you with this final thought
(below)…
Hey Charlie, nice post. What do you think about intentionally inputting aerosols into the atmosphere to combat climate change? Would that actually help or is it simply an example of mankind implementing itself into nature even more? I look forward to your reply :)
ReplyDeletePersonally, and i feel quite strongly about this, I think this is an absolutely ridiculous idea! Firstly, this is only a short term tech fix and we should be focusing on cutting emissions instead. Secondly, and in relation to the Arctic, aerosols upset the natural energy budget and could potentially cause warming (through indirect effects) or cooling (through direct effects). I don't think anyone can be sure how this region, or the global climate system in fact, will react to having large amounts of unnatural aerosols pumped into the atmosphere and i don't think it is worth the risk. What is your opinion on this?
DeleteReally helpful to learn more about aerosols as I don't think they are given much attention in the mass media! Which aerosols have cooling properties, and which having warming tendencies?
ReplyDeleteGenerally aerosols are known to have cooling properties and the direct effect of most is to cool surface temperatures as they scatter and absorb the visible radiation. This is often the case with Arctic haze which contains a lot of sulfates (which scatter light) and black carbon (which absorbs light) and when above a high albedo surface causes a drop in surface temperatures. The indirect effects of aerosols are slightly more complex... Aerosols influence the properties of clouds in this region but causes seasonal warming when the clouds are warmer than the surface below. Hope that has answered your question!
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