July 22, 2003

A Pew Initiative on Food and Biotechnology spotlight

Can biotechnology save the planet? When most people hear that question, they probably think about genetically modified food or new drugs. But the same technologies that are being developed for farms and pharmaceuticals have scientists speculating that biotechnology could hold some promise for moderating global warming caused by the greenhouse effect.

The greenhouse effect is caused when more solar energy is trapped in the Earth's atmosphere than can escape into space. Carbon-containing gases like carbon dioxide and methane are high on the list of compounds that tend to hold heat in the atmosphere — so the more of these gases in the atmosphere created by doing things like burning fossil fuels, the warmer things get.

As the world continues to rely on fossil fuels for energy, the amount of carbon going into the atmosphere continues to increase as it overwhelms nature's ability to remove it. As a result, anything that takes the carbon compounds out of the atmosphere – directly or indirectly — would help slow down the greenhouse effect to some degree. And, that's where biotechnology may come into play.

Generally speaking, there are two fronts in the battle to reduce carbon in the atmosphere: 1) releasing less carbon into the air by burning less fossil fuels and 2) locking up, or "sequestering," more carbon from the air into the ground and oceans.

Researchers are focusing on several possible ways biotechnology might help on both fronts. One way is to employ GM plants that are already in use — but for different reasons. GM crops already being designed to withstand wind could help sequester more carbon into soils, says agronomy professor Charles Rice of Kansas State University.

For example, corn that is engineered to grow thicker, woodier stalks uses more carbon. The carbon is needed to make all the woody lignin and cellulose that makes them thicker and stiffer. Lignin and cellulose are slow to decompose in the soil, so, says Rice, "The more biomass you produce, that means more carbon that's put into the soil."

The same trait could be added to other crops with the express purpose of locking up more carbon instead of making a sturdier plant. Imagine, for instance, a tomato plant that's woodier, but yields the same fruit. However, developing such a tomato may not be such a simple matter, because any time
crops are bred for one trait (either conventionally or through biotechnology) there may be unacceptable trade-offs in fruit quality or environmental impact of the crop.

Nevertheless, efforts to increase carbon sequestration aren't focused solely on crop plants. Other plants that may help sequester carbon are grasses, says Scott Angle, a microbiologist at the University of Maryland. The Department of Energy's Center for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems (CSiTE) is studying grasses, trees and all manner organic and inorganic ways to sequester carbon in an effort to enhance carbon capture and long-term sequestration in terrestrial ecosystems
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Jeff Fiedler, a climate policy specialist with the Natural Resources Defense Council, says research to engineer plants for climate purposes is all well and good, but these efforts don't address what needs to be done today. "I really don't want to rain on anybody's parade, because we need all the help we can get" he says. "But, in the U.S. the two biggest emitting sectors are power plants and transportation. There is no way we are going to address global climate change without reducing the emissions in these sectors. And biotechnology is unlikely to develop a silver bullet for these two sectors."

Even though it may not be a "silver bullet", Angle says that "no till" agriculture — the use of more herbicide-resistant GM crops to control weeds instead of tilling the ground — can help reduce emissions and sequester carbon. Weed tilling not only uses up tractor fuel (which releases carbon into the atmosphere), but it exposes soil carbon to oxygen, with which it reacts and escapes back into the atmosphere. Angle believes no till crops offer a double benefit.

Engineered soil microbes may also help to sequester more carbon, says Rice. Like every living thing, bacteria and fungi use carbon in nearly every molecule. If these could be made to take on just a little more carbon, they could add up to a lot more carbon sequestration. Particularly promising in the subterranean side of this matter are fungi, which create a lot of biomass underground, but are not well understood.

Looking at ways to use fungi from another angle is fungus geneticist Linda Lasure of Battelle at Pacific Northwest National Laboratory, a Department of Energy Laboratory. Lasure is trying to see if fungus might be made better at breaking down cellulose to create usable fuels out of agricultural waste:
essentially, ethanol or hydrogen out of husks. She can imagine someday driving a car with an electric motor and a hydrogen fuel-cell power plant that you fuel with grass clippings from your yard.

Today even the few experimental hydrogen fuel cell cars on the road get their hydrogen from fossil fuels — which neither helps reduce carbon or U.S. dependence on oil importation. Both are goals of the U.S. Department of Energy, explains Lasure.

The fungi that are best understood are the yeasts, which we've been using for centuries to create fuels such as ethanol and other alcohols, Lasure explains. But it's another kind of fungus that holds the most promise, she says: filamentous fungus commonly found in soils. Unfortunately these are also the least understood fungi. That's why she's paying close attention to them now to identify species and discover what they can do.

These sorts of possibilities combined with increasing concerns about global warming have created the potential for biotechnology to play a role in mitigating greenhouse gases. In fact, efforts are now underway to deliberately find biotechnological applications — instead of coming across them as afterthoughts, as has been done in the past.

"All of this derives to date from research and development aimed at agriculture, industrial processing and environmental clean-up," says Blaine Metting, also of Battelle, Pacific Northwest National Lab. Metting's specialty is looking at how hydrogen can be made from microbes. "(It's) safe to say, however, that in the future biotech will be directly aimed at greenhouse gas mitigation — CO2 and
the other gases."

Even though work will be aimed at mitigating greenhouse gas emissions, Fiedler notes that it's important to remember any technology being developed today is unlikely to bear fruit for 20 to 50 years.

"One thing we are often worried about is people coming up with grand technical solutions that say ‘if you just wait 20 years, we'll solve the problem for you,'" he says. "We don't want to wait — we don't have that kind of time. And, we can't rely on one technology because some ideas will work, some won't work, and some of them are bad ideas for other environmental reasons."

"That's not to say that biotechnology won't play a role in mitigating greenhouse gases," Fiedler says. "But not all these things are going to be judged socially beneficial when all the tradeoffs are considered. We need to reduce emissions now — there is no technological silver bullet that will change that."

For more information, please visit the DOE cSITE; the Rice Lab; the Angle Lab; the Pacific Northwest National Laboratory; and the National Resources Defense Council online.