Monday, 26 October 2015

Effects Of The Albedo Effect

The paper published by Pistone et al in 2014 gives a numerical insight into the albedo effect and its influence on the melting polar ice sheets. The albedo effect is how much sunlight is reflected by a particular material such as ice or sea. All objects have an albedo score between 0 and 1. The darker an object, the more sunlight energy is absorbed and conversely the lighter an object, the more light energy is reflected. The paper by Pistone is informative and shows that the albedo in the Arctic has decreased from 0.52 to 0.48 W/m2 from 1979 and 2011.
Ice is white and therefore reflects most of the sun's energy and has a high albedo. At the poles, light is reflected by the ice sheets and gives a cooling effect. However with global warming, the cryosphere is melting which reduces the amount of ice present at the poles. More dark sea is exposed which has a much lower albedo. Having a lower albedo, more of the sun's energy is absorbed which produces a positive feedback effect where by the dark sea becomes warmer which in turn enhances global warming through thermal expansion of the oceans.
Fig. 1.Figure 1: This image taken from Pistone's 2014 paper illustrates the melting of the Arctic sea ice in picture C between 2007 and 2011 (source).
Consequently, the image in D shows a lower albedo where the dark sea absorbs the sun's energy, lowering the albedo. These images show that the cryosphere is indeed melting. As 97% of all climate scientists believe that anthropogenic global warming is taking place, the albedo effect will be a major factor in the control of feedback mechanisms that can control global warming.


For humans, the positive feedback mechanism is not a short term change but long term. The effects will not be sudden but will happen over time. The main impact on humans are the rising sea levels which are produced by thermal expansion due to a lower albedo producing enhanced global warming.


The next post will focus on the thermohaline circulation and its effects on the melting cryosphere.
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2 comments:

  1. Maria Christofi26 October 2015 at 08:01

    Interesting topic! I was wondering, due to the albedo cooling the earth, would it not be a major impact for humans, if in the long run ice melted, hence leading to the globe warming in higher rates? (or does the albedo effect have a smaller cooling effect that would not have such a great impact on Earth if it all disappeared?)

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    1. Laura Marriott29 October 2015 at 04:05

      Thanks for posting! In the long run it would have a massive impact for humans with rising sea levels putting major low lying cities such as London at risk. The ice melting would have a major impact on the albedo effect. The less ice, the smaller surface area there is to reflect the sun's energy back into space. Consequently there would be more dark ocean which would increase thermal expansion due to an absorption of the sun's energy, accelerating global warming.

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