Thursday, December 5, 2013

New paper finds warming & CO2 increase wheat production in central Asia

Climate Change Impacts on Wheat Production in Central Asia 

A team of 20 researchers reports that “the overall simulated impact of climate change on wheat productivity in Central Asia is positive,” noting that “a warmer climate explains most of this positive impact” and that “CO2 fertilization adds to it.”

Sommer, R., Glazirina, M., Yuldashev, T., Otarov, A., Ibraeva, M., Martynova, L., Bekenov, M., Kholov, B., Ibragimov, N., Kobilov, R., Karaev, S., Sultonov, M., Khasanova, F., Esanbekov, M., Mavlyanov, D., Isaev, S., Abdurahimov, S., Ikramov, R., Shezdyukova, L. and de Pauw, E. 2013. Impact of climate change on wheat productivity in Central Asia. Agriculture, Ecosystems and Environment 178: 78-99.

According to Sommer et al. (2013), "global warming and related climate change (CC) may pose a major challenge to agriculture and rural livelihoods in Central Asia, with its five countries Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan and Turkmenistan." And "in view of the little hard data at hand," as they continue, they say "there is considerable uncertainty about the impact of CC," concluding, therefore, that "the sub-region is clearly in need of more climate change-related research."

To address this issue, Sommer et al. assessed the crop growth and yield of 14 wheat varieties grown on 18 sites in key agro-ecological zones of Kazakhstan, Kyrgyzstan, Uzbekistan and Tajikistan in response to two projections of climate change - the IPCC (2007) SRES scenarios A1B and A2 - comparing the results against historic (1961-1990) figures, where the impact on wheat was simulated with the CropSyst model (Stockle et al., 2003) that distinguishes three levels of agronomic management.

The 20 researchers report that "the overall simulated impact of climate change on wheat productivity in Central Asia is positive," noting that "a warmer climate explains most of this positive impact" and that "CO2 fertilization adds to it." They do acknowledge, however, that "too hot temperatures during flowering will become a problem in the long-term future in some, mostly southern, areas and in the spring wheat areas of northern Kazakhstan." But they say that "the picture is not unduly dramatic, and targeted crop breeding towards temperature tolerance in combination with improved agronomic management (shifting planting dates) may be able to tackle the issue." And in light of the projected "improved transpiration use efficiency in response to elevated atmospheric CO2 concentrations," they report that "irrigation water requirements of wheat did not increase."

In concluding their paper, Sommer et al. write that "development of adaptation options to CC was part of the original objectives of the study." When all was said and done, however, they decided that "given the generally positive impact of CC on wheat productivity in Central Asia, there remains little to be argued about adaptation needs for farmers," other than to mention that adaptive changes in sowing dates, cultivar traits and inputs "might lead to even further yield increases," which sounds like a pretty good future, indeed.

Additional References
IPCC. 2007. IPCC Fourth Assessment Report: Climate Change 2007 (AR4).

Stockle, C.O., Donatelli, M. and Nelson, R. 2003. CropSyst, a cropping systems simulation model. European Journal of Agronomy 18: 289-307.

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