Predicting the impact of changing CO₂ on crop yields: some thoughts on food

• Published in: The New phytologist Vol. 175; no. 4; pp. 607 - 618
• Main Authors: Ziska, Lewis H., Bunce, James A.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-01-2007; Blackwell Science; Blackwell Publishing Ltd
• Subjects: Atmospherics; carbon; Carbon dioxide; Climate change; crop production; Crop science; crop yield; Crops; elevated atmospheric gases; elevated CO2; food security; Glycine max; literature reviews; Oryza sativa; Ozone; phytotoxicity; plant damage; plant growth; Plants; Rice; soybean; Soybeans; Tansley Review; Triticum aestivum; Wheat
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2007.02180.x

Recent breakthroughs in CO₂ fumigation methods using free-air CO₂ enrichment (FACE) technology have prompted comparisons between FACE experiments and 'enclosure studies' with respect to quantification of the effects of projected atmospheric CO₂ concentrations on crop yields. On the basis of one such comparison, it was argued that model projections of future food supply (some of which are based on older enclosure data) may have significantly overestimated the positive effect of elevated CO₂ concentration on crop yields and, by extension, food security. However, in the comparison, no effort was made to differentiate 'enclosure study' methodologies with respect to maintaining projected CO₂ concentration or to consider other climatic changes (e.g. warming) that could impact crop yields. In this review, we demonstrate that relative yield stimulations in response to future CO₂ concentrations obtained using a number of enclosure methodologies are quantitatively consistent with FACE results for three crops of global importance: rice (Oryza sativa), soybean (Glycine max) and wheat (Triticum aestivum). We suggest, that instead of focusing on methodological disparities per se, improved projections of future food supply could be achieved by better characterization of the biotic/abiotic uncertainties associated with projected changes in CO₂ and climate and incorporation of these uncertainties into current crop models.