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Saturday, January 24, 2009

Corn to cool the earth

Corn to cool the earth

Dr J D Bapat

A new study finds that increasing the glossiness or reflectivity of crop surfaces could cool earth in the summer. The scientists view it as the most cost-effective geoengineering solution for global warming.

The waxy coating of crops such as corn and barley reflects solar radiation back into space--a property called "albedo." Without crop albedo, estimates suggest that Earth would be approximately a half a degree Celsius warmer than it is now. If researchers increase the crop albedo further, they could help cool our warming world. Increasing crop albedo by 20% could decrease regional temperatures by 1°C in the summer. Over 100 years, the effect would equate to eliminating 195 billion tonnes of CO2 from the atmosphere, the equivalent of grounding 195 million plane flights from Los Angeles to New York. One way to increase albedo is to selectively breed plants with thicker waxy layers.

Modifying the crop albedo offers advantages not found in other geoengineering proposals, such as practicality and low cost to implement. However it should be noted that making crops more glossy will not solve global warming by itself. It is a simple, small step that we can take to start making a difference.

Researchers propose that one way of temporarily reducing global temperatures would be to replace existing crops with variant strains that reflect more solar radiation back out to space. The overall effect would be the same as making large areas of the planet more mirror-like. Their calculations suggest this could cause average summer temperatures in temperate zones to fall by as much as 1°C.

The politicians have generally adopted the aim of limiting global warming to 2°C above 19th century averages, so a 1°C is not something to be taken lightly.

Plants reflects short wave energy back out to space much like snow and other light surfaces do. As Arctic ice melts and is replaced by dark water, for instance, the region's warming is expected to accelerate . Plants have higher or lower reflectivity depending on things like the shape and size of their leaves and how waxy they are. Different varieties of a same species can have more or less albedo.

The crop yields would not suffer, if farmers preferentially planted high-albedo varieties. Indeed for some crops yields might increase. The farmers would need to be given incentives – most likely financial ones – to buy high-albedo varieties. The researchers say one way of setting up these incentives would be to make high-albedo farms eligible for carbon credits which could be sold on the carbon trading markets.

Source: ScienceNOW Daily News, 15 January 2009

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