Scientists believe that planting trees in African coastal deserts could capture carbon dioxide.

Additional benefits from planting trees would include reducing harsh desert temperatures, boosting rainfall, reversing soil degradation and allow for the production of inexpensive biofuels.

Trees proposed for the plantations include Eucalyptus microtheca and Jatropha curcas, the latter already the subject of intensive scientific research worldwide as a leading contender to produce abundant biofuel from its seed pods, which have a high oil content.

The proposal is outlined in a study published last month by Earth System Dynamics, based on data compiled in Mexico and Oman, All Africa news agency reported on Monday.

The Earth System Dynamics study states that "large-scale plantations of Jatropha curcas - if established in hot, dry coastal areas around the world - could capture 17-25 tons of carbon dioxide per hectare per year from the atmosphere (over a 20 year period). Based on recent farming results it is confirmed that the Jatropha curcas plant is well adapted to harsh environments and is capable of growing alone or in combination with other tree and shrub species with minimal irrigation in hot deserts where rain occurs only sporadically. Our investigations indicate that there is sufficient unused and marginal land for the widespread cultivation of Jatropha curcas to have a significant impact on atmospheric CO2 levels at least for several decades."

Other trees that could be used in the "carbon farming" plantations include Acacia saligna, Azadirachta indica, Eucalyptus camaldulensis, Moringa oleifera and Pongamia pinnata, along with shrubs such as Prosopis cineraria, Ricinus communis and Simmondsia chinensis, and reeds and grasses such as Arundo donax L, LIHD-prairie grasses and Miscanthus x giganteus.

Klaus Becker, the "Carbon farming in hot, dry coastal areas: an option for climate change mitigation" study's lead author and director of carbon sequestration consultancy Atmosphere Protect, projects that a jatropha plantation covering just 3 percent of the Arabian Desert could absorb all the carbon dioxide produced by cars in Germany over two decades. Becker added, "Our models show that, because of plantations, average desert temperatures go down by 1.1 degree Celsius, which is a lot." An added benefit of the plantations is that they would also induce rainfall in desert areas.

Desalinated water and sewage would be used for irrigation. Becker noted, "There are billions and billions of liters of sewage that are discharged into the oceans every week, but instead we could send that water to the desert and plant trees. In this situation, you wouldn't need any expensive artificial nitrogen (for fertilizer)."

A possible problem in implementing such plantations would be that many African smallholder farmers lack adequate and reliable information about how to participate in agricultural carbon credit projects, according to a study published last month by the Consultative Group on International Agricultural Research Research Program on Climate Change, Agriculture and Food Security.

Moses Masiga, one of the report's authors, said, "We know that many more farmers would consider the opportunity of participating in mitigation projects. However, a market failure of access to adequate and reliable information limits this participation."