Agro-Ecosystems and Grasslands
Since atmospheric CO2 enrichment results in increased photosynthetic fixation of carbon, in an elevated-CO2 world of the future more carbon should be stored in the soils of farmers' fields and natural grasslands. This sentiment is shared by many researchers; and it has been succinctly stated by Sombroek et al
. (1993) in their analysis of tropical and subtropical agriculture:
"The CO2 fertilization effect is likely to have a significant impact on plant growth in the humid tropics in a CO2 enriched atmosphere, yielding extra soil organic matter through litterfall and crop residues, and especially through a more vigorous root growth . The CO2 antitranspiration effect would be of particular significance in the semiarid regions of the tropics and subtropics: plants would grow more vigorously with the same amount of water, and some plant growth would become possible where hitherto the land surface [has been] bare, due to climate- or salinity-induced aridity. A better ground cover would be the result, limiting soil-erosion hazards, lowering the soil-surface temperatures and providing fresh organic matter for incorporation in the soil."
As research in this area has progressed, CO2-induced carbon sequestration has been observed in the soils of several agro-ecosystems, while other studies have demonstrated the potential for this phenomenon to occur on abandoned agricultural land and natural grasslands and savannas, especially in conjunction with the CO2-enhanced nitrogen fixation that is provided by grain and forage legumes.
Sombroek, W.G., Nachtergaele, F.O. and Hebel, A. 1993. Amounts, dynamics and sequestering of carbon in tropical and subtropical soils. Ambio 22: 417-426.
** For additional peer-reviewed scientific references and an in-depth discussion of the science supporting our position, please visit Climate Change Reconsidered: The Report of the Nongovernmental Planel on Climate Change (www.climatechangereconsidered.org), or CO2 Science (www.co2science.org).