Cool crops. More reflective plants may help us trade the warming depicted on the left (darker hues of red) for the cooling effects seen on the right as this century comes to a close.

Joy Singarayer

Global Warming: Corn to the Rescue?

From a trillion dollar space-based sunshield to painting every roof in the world's cities white (ScienceNOW, 16 September 2008), scientists have dreamed up creative ways to fight global warming. Now researchers are putting forward a more cost-effective geoengineering solution: enhancing the "glossiness" of crops. A new study finds that increasing the reflectivity of crop surfaces could cool central North America and Eurasia during the summer months.

The waxy coating of crops such as corn and barley already 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, says geologist and climate scientist Andy Ridgwell of the University of Bristol in the U.K. To him, it stood to reason that if researchers could somehow increase crop albedo further, they could help cool our warming world.

To test the idea, Ridgwell and colleagues gathered data about croplands around the globe, most of which are concentrated in North America and Eurasia. Then, they modeled how changes in crop albedo would impact global temperatures using atmospheric circulation, sea-ice formation, and other known climate patterns. 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, the team reports today in Current Biology.

One way to increase albedo is to selectively breed plants with thicker waxy layers, says Ridgwell. The change doesn't affect plant productivity, he says, and consumers shouldn't have a problem with these modified crops, because we don't eat the leaves. The enhanced plants could be a boon to farmers as well: "It may be that waxier leaves provide other benefits, [like] reduced water loss for instance."

Fitzgerald Booker, a plant physiologist at the United States Department of Agriculture in Raleigh, North Carolina, says that modifying crop albedo "offers advantages not found in other geoengineering proposals, such as practicality and low cost to implement." Although Ridgwell admits that making crops more glossy won't solve global warming by itself, "it's a simple, small step that we can take to start making a difference."