Albedo Part 2 by Gillian
I have been doing some more research on this rather interesting topic and wanted to share some of my new finding with you all!
An ice or snow surface is a powerful reflector of of solar radiation (the albedo is a measure of its reflectivity). As some ice melts, therefore, at the warmer surface, solar radiation which had previously been reflected back to space by the ice or snow is absorbed, leading to further increased warming. (Houghton 1994)
Henson (2008) points out the darker surfaces absorb more sunlight and in turn warm the air above it more strongly. Bunyard (1999) shares similar views. He argues that a highly reflective surface such as fresh snow has an albedo of around 90%. As ice and snow melt, exposing ground, more heat is absorbed, which leads to more melting and the exposure of more ground. This snowball effect is characterized as positive feedback. Open ocean typically absorbs more than 90% of the solar energy reaching it, while snow and ice absorb as little as 10% reflecting the rest of the sunlight off their white bright surfaces.
Henson (2008) argues that not only are polar bears at risk of being greatly depleted in numbers but the ice also takes on many other roles. It provides a roadbed for people and a shield for coastal towns and underwater creatures. All of which could be greatly affected by the decreased albedo and global warming. In fact, a 2007 study by the US Geological Survey predicted that based on current trends, two thirds of the Earth’s polar bears will be gone by 2050 and that several species of seals will also be at serious risk.
Due to rising sea levels in the Arctic, experts believe that the twenty-first century will likely bring a summer where the Arctic Ocean is entirely free of ice for the first time in nearly a million years. These changes threaten to reorder the Arctic ecologies in dangerous and unpredictable ways.
Diagram illustrates how solar radiation hitting snow or ice (lighter coloured surfaces) is reflected back out into space. This is referred to as the 'Albedo effect'.
References -
Bunyard, P. (1999) The Breakdown of Climate. Edinburugh: Floris Books
Henson, R. (2008) Climate Change. 2nd edn. New York : Rough Guides Ltd.
Houghton, J. (1994) Global Warming. Oxford: Lion Publishing.
Hi Gillian, that last sentence is really powerful! It certainly serves to heighten our awareness of this issue let alone try to, at the very least, slow down the inevitable due to our pursuit of modern day science and engineering.
ReplyDeleteComment placed by Vicky Mitchell
DeleteYes, it is quite frightening to think of the future with not only rising sea levels destroying islands and low lying areas but also what can happen to so many species of animals.
ReplyDeleteI was just browsing through a book on Climate Change and the Polar bears....it states that each year the sea level melts earlier and freezes later. As a result of this the bears' hunting season is getting shorter, making it hard for them to catch enough food to survive. What will happen in the next few years?? When will people wake up and realize what we are doing to our planet and ourselves??? G
I know, it is a frightening and sad thought, but a part of me wonders if this is how it is meant to be! Maybe this is what is supposed to happen?? The dinosaurs died out! Mankind has evolved into an intelligent species! Vicky
ReplyDeleteWell maybe this is the way it is supposed to be however WE can certainly try to control how fast/ slowly it happens! G
ReplyDelete