Human World

Andy Ridgwell’s reflective crops may help curb global warming

A scientific study has shown that farmers could help curb global warming by planting crops with leaves that reflect more sunlight – and heat – back into space.

Andy Ridgwell: We know that the composition and the amount of wax on leaves is important. And the waxier the leaf, in general, the more reflective it is. We also know that how the leaves are arranged in the canopy can make a big difference as to how much sunlight is reflected back from the crop.

That’s climate scientist Andy Ridgwell of the University of Bristol. Using computer modeling, he calculated that crops with waxier leaves – which are therefore more reflective – would have a cooling effect on Earth, especially on major agricultural areas.

Andy Ridgwell: In the summertime when the crops are in leaf, and they’re reflecting slightly more sunlight away, you get a cooling of maybe about a degree in North America and a degree in Europe.

He said that might not sound like much.

Andy Ridgwell: But it will take the edge off the frequency and intensity of heat waves which, certainly in Europe, are becoming a big issue.

Ridgwell added that seeds for crops with greater reflective power aren’t yet commercially available. Plus, he said, it’s not known how food from these special crops would compare in taste and feel. He said more research is needed.

Ridgwell spoke about the computer modeling used to study the possibility of cooling via crops with waxier leaves.

Andy Ridgwell: It is generally impossible to perform ‘experiments’ with our planet. Instead, we have to rely on computer models as our analytical tools and experimental laboratories for helping understand the workings of the climate system and for predicting future climate change. They use our best physical understanding of how the climate system works to simulate how energy and water are redistributed on Earth. Because it is not possible to keep track of the energy and position of every single molecule, the atmosphere and ocean are divided up into a 3-dimensional grid, often of tens of thousands of different boxes.

He emphasized that the impact of more reflective crops would mainly be felt in and around Earth’s major agricultural areas – in North America, Europe and Central Asia.

Critics suggest that – although waxier crops might have a slight cooling effect – what’s truly needed is an overall reevaluation of current farming practices. For example, some believe it might be possible to create a cooling effect by de-centralizing agriculture across Earth’s surface, rather than leaving it concentrated in North America, Europe and Central Asia. If there were so, there would be no need for special plants with waxier leaves to create more reflectivity.

September 7, 2009
Human World

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