A cheap and simple way to buffer the greenhouse effect

by Heinrich Pesch

As far as I know, this idea hasn't been presented elsewhere-although I haven't exhaustively researched this. The underlying idea has already been mentioned in James Lovelock's Gaia hypothesis.

Most climate scientists today agree that CO2 emissions from the industrialised nations will lead to a warming of our climate in the near future. A proposal to relieve the situation was agreed in the Kyoto accord for the reduction of emissions, mainly through savings on fossil fuels. Other alternatives assume that the world's population simply has to adapt to the climatic warming. There is no question that the suggested defensive measures would lead to immense cost s and would only take effect after a delay: this prompted the current government of the United State of America to snub the signing of the Kyoto accord. Other principal contributors to excess atmospheric CO2 are sceptical too, including Russia and China.

My idea approaches the problem from a different direction. Instead of protracted changes in our energy industry to reduce CO2 emissions, my question is: Isn't there a faster and cheaper way to achieve climatic cooling?

Instead of lowering or stabilising the CO2 content of the atmosphere, my proposal would be to increase the reflection of radiation away from the planet and into space.

The Earth reflects on average around 33% of the radiation arriving from the sun. The proportion of radiation that a body or surface reflects is known as its albedo. The Earth's albedo of 0.33 is a value between that of the moon (0.12) and of Venus (0.76).

Freshly fallen snow reflects 75 to 90 % of incident radiation, whereas a grain field reflects just 10 - 25%, as do forest and woodland, and water reflects just 10 %.

Anybody flying over a densely populated area such as Western Europe on a clear day will immediately see the considerable proportion of the Earth's surface taken up by buildings and road surfaces. The albedo of building materials varies greatly from white-painted surfaces (0.90) to dark asphalt (0.05). The average albedo for a city is estimated to be around 0.15.

My proposal is based on the presumption that it is relatively easy to influence the albedo of populated areas. Instead of dark materials, we should favour materials that are as bright as possible. The traditionally dark surfaces in cities lead to temperatures that are around 1% warmer than those of the surrounding countryside.

The continuing climatic warming is causing the glaciers to recede. Some fear that the resulting loss of white surface area - in the Alps, for example - with its high albedo and cooling effect on our climate, will lead to an acceleration in climatic warming. Certainly, the surface area of built-up areas in Europe is significantly larger than that of the permanent snow in the Alps; an increase in the albedo of our residential and industrial areas could actively contribute to counteracting this threat.

The nearer a building or road surface is to the equator, the higher the cooling effect from using brighter building materials would be. Particular attention should be paid to walls and roofs that face the sun. Were the villagers of southern Asia to colour their roofs white, a measurable global cooling effect is certain to result. Overall, I would count on the private initiative of the people, and rather less on governmental programmes. Countries close to the equator are those most threatened by the consequences of climatic warming and will profit the most from successfully averting the danger.

This idea was published for the first time on January 9th, 2004 in my letter to the editor of "Helsingin Sanomat", the Finish daily newspaper.