ROOT CAPACITY: Perennials like Miscanthus have extensive root systems, which can trap more carbon in the soil than the smaller root systems of annuals.
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Human activities currently add about nine gigatons of carbon to the atmosphere yearly. Photosynthetic organisms on land and in the ocean absorb about five of those gigatons through the natural uptake of CO2, leaving to humans the task of dealing with the rest. But no matter how much carbon there is, capturing it and preventing it from reentering the atmosphere is an immense engineering challenge; even today's best technology is orders of magnitude less effective than photosynthesis at trapping atmospheric carbon.
A new analysis published in the October issue of Bioscience suggests that by 2050 humans could offset between five and eight gigatons of the carbon emitted annually by growing plants and trees optimized via genetic engineering both for fuel production and carbon sequestration.
Bioenergy crops represent an opportunity to mitigate atmospheric carbon dioxide in two separate ways, says lead author Christer Jansson, a senior staff scientist at Lawrence Berkeley National Laboratory's Earth Sciences Division. First, they are a carbon-neutral energy source that could offset the burning of fossil fuels. Second, "if they are the right kind of plants, they have a chance to transfer a lot of carbon underground for long-term sequestration," he says.
Plants take up CO2 and store carbon in their biomasses. Carbon can stay for decades or centuries in leaves, stems, branches, seeds and flowers aboveground, whereas carbon allocated to underground root systems is more apt to be transferred into the soil, where it can stay sequestered for millennia. Therefore, an ideal bioenergy plant would produce lots of aboveground biomass for fuel as well as have an extensive root system. Preliminary research indicates that genetic engineering approaches could be employed to enhance both these traits.
Using genetic modification to enhance photosynthesis and thus biomass yield is a realistic approach, says Stephen P. Long, a professor of crop sciences at the University of Illinois at Urbana–Champaign who was not part of the study. Long notes that transgenic tobacco plants, with simple modifications applicable to other plants as well, have already been shown to be more productive. "We are in a position now where we certainly know enough to where we could engineer quite a few of these changes," he says.
Meanwhile, regarding the problem of coaxing plants to allocate more carbon to their root systems, Jansson says an important difference between perennial and annual plants is a good place to start. "Perennials are more efficient than annuals at hiding carbon underground," he says. That's because annuals, which make up most of the world's food crops, spend much more energy producing seeds, stems and leaves than for building their root systems. On the other hand, perennials like switchgrass and Miscanthus have more extensive root systems—necessary because they remain dormant for part of the year and then must grow up again from their roots.
Whereas it may be exciting to imagine a bioenergy or food crop that produces lots of aboveground biomass and has large, carbon-sequestering root systems, research into whether this goal is realistic is still in its early stages. "Perenniality is a complex trait," Jansson says. He suggests it may end up being easier to modify perennials so they possess desirable annual-like features, as opposed to the other way around—but it's too early to tell.
For the short term Jansson is confident that science can modify plants so they are more drought resistant and salt tolerant. Crops that could be maintained with brine or brackish water, such as industrial wastewater or seawater, would help preserve freshwater supplies. "These are important traits that need to be introduced into food and bioenergy crops," Jansson says, adding that "we will see this sooner" than enhanced photosynthesis or perennials with annual traits and/or vice versa.
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9 Comments
Add CommentGenetic engineering at the present state of the art/science can be compared to providing 2 year olds with matches. Let's not forget Klebsiella planticola the bacteria universally found at the roots of all terrestrial vegetation. Geneticists added an additional alcohol gene and were preparing to use it to turn field stubble into alcohol instead of burning it. Fortunately, A team of independent scientists decided to do their own tests and found that the GE modified organism, if loosed in the environment would kill all the vegetation on Earth. Scary enough for you?
Reply | Report Abuse | Link to thisRight. Because, of course, we all know that when you increase a food supply (CO2) into an ecosystem, there is absolutely no responding increase in population.
Reply | Report Abuse | Link to thisThis, folks, is what passes for science today.
I am amazed how "science" jumps at genetic modification of our natural world for a singular fix, in this case global carbon-sequestration, without taking into account the impact of what would alter an entire biodiverse ecosystem. With all due respect, science does not know enough about the intricacies of the balance and crucial inter-relations of the natural world's web of life to begin messing with a singular aspect which could well produce more problems than it solves. Tuning in to nature's needs to restore and bring balance back to Her would be a better use of our great scientific minds instead of finding excuses not stop doing what we have created...in this case, producing more carbon into the atmosphere!
Reply | Report Abuse | Link to thisFurther to my earlier comment, I respectfully refer you to the opening statements of the UN Convention on Biological Diversity (CBD) happening in Japan this week.
Reply | Report Abuse | Link to thisUN: Loss Of Biodiversity Could Mean End Of Human Race - CBD executive secretary Ahmed Djoghlaf said in his opening statements. "We need a new approach, we need to reconnect with nature and live in harmony with nature into the future."Business as usual is not an option http://ht.ly/2Wj4X Full Report: (UNEP) -- http://ht.ly/2Wjd7
Combine this with vertical urban farming and you've got CO2 sinkage where an awful lot of the stuff is produced.
Reply | Report Abuse | Link to thisBut it would be even better to see plants (or any organisms for that matter) successfully optimized to sequester methane or chlorofluorocarbons.
Anyway, the good thing is that renewable fuels will reduce the amount of greenhouse gases emitted, while organic gas traps will increase the amount sequestered. Double whammy.
I concur with all your remarks and wonder when we will recognizance and and pay for the true cost of carbon.
Reply | Report Abuse | Link to thisI have been suggesting a carbon tax that would replace all existing taxes, this would then concentrate all minds from beginning to end of the life cycle of all goods and services as to the true value of carbon and its effects on the planet.
I had the same idea a couple of years ago. The fact is that once captured you must get rid of it if we want to lower CO2 concentration in the atmosphere. So as for CO2 sequestration (pumping compressed CO2 underground) grown plants must be pulverized and than pumped beneath the soil adding water. Using the grown plants as biomass to produce energy will surely not lower carbon concentration in the atmosphere hence global warming.
Reply | Report Abuse | Link to thisGenetically modifying crops could have unexpected long-term side-effects, like making species targets for previously harmless predators. We need more time to guage the overall effects of genetic tinkering.
Reply | Report Abuse | Link to thisGreat post. One can grow Agave in waste lands to increase global carbon sequestration. It is a care-free growth plant. Biofuel can be extracted from this plant. Since it has cellulose,it can be used as input in paper making. In Brazil it is done. Also Hecogenin a steroid is extracted from this plant.
Reply | Report Abuse | Link to thisDr.A.Jagadeesh Nellore(AP),India
E-mail: anumakonda.jagadeesh@gmail.com