Humans emit about nine billion metric tons of carbon a year, about five of which are absorbed by ecosystems on land and water, leaving four to accumulate in the atmosphere and warm the planet.
Plants can sequester carbon temporarily in their leaves, trunks and stems. Once the plants die and other organisms degrade the plant material, the CO2 is released into the atmosphere again.
But plant roots provide longer-term storage, as does burned plant material, which can stay in the soil for hundreds or thousands of years as charcoal.
Genetic modification could potentially improve rates of photosynthesis or the amount of biomass stored in roots, leading to more carbon stored for the long term, the team noted.
"For bioenergy crops, the needs are to grow on marginal land and be tolerant to different kinds of stress, and engineered to grow in saline water or brine rather than fresh water," Jansson said.
"Freshwater is a rare commodity and it will be even more precious in the near future," he added.
"In certain areas, genetic engineering can contribute quite a bit," Jansson said, including improved stress resistance and photosynthesis. "I don't think it's just around the margins. Using proper controls, I think it could be a valid approach."