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Divining Future Winter Wheat Yields in the United Kingdom

Cho, K., Falloon, P., Gornall, J., Betts, R. and Clark, R. 2012. Winter wheat yields in the UK: uncertainties in climate and management impacts. Climate Research 54: 49-68.
Introducing their work, authors Cho et al. (2012) write that "winter wheat is currently the most extensively grown arable crop in the UK," the climate of which "allows winter wheat to be grown throughout the winter, achieving larger yields than varieties that are planted in spring." However, they state that "recent climate projections show changes in temperature and precipitation are likely, potentially affecting UK crop yields." And, therefore, they felt it important to attempt to ascertain what the consequences might be for winter wheat yields throughout the UK's 13 main administrative regions, based on the climate-modeling work of Jenkins et al. (2009), which projected mean daily maximum temperatures in the UK "to increase by between 1.0 and 9.5°C in the summer and by between 0.7 and 2.7°C in the winter by the 2080s." More specifically, Cho et al. assessed the wheat yield implications of these projected climate changes by means of the CERES-Wheat model for "an ensemble of regional model projections and different sowing dates and fertilizer regimes." And what did that assessment reveal?

The five UK researchers report that their "sensitivity analyses of climate variables on future winter wheat yield in the UK generally indicated positive impacts from climate change," where "increases in temperature and atmospheric CO2 concentrations appear to contribute positive impacts on potential yield, greater than from increases in precipitation. As indicated in the Table below, although some of the southern regions suggest a potential decline in future wheat yields, that finding "may not be critical for wheat production in the UK as a whole, as losses in some regions are more than compensated by gains in others [italics added]."

Observed and future UK winter wheat production and changes compared to the baseline using the unperturbed climate simulation. NS: Northern Scotland, WS: Western Scotland, ES: Eastern Scotland, NI: Northern Ireland, NW: North West England, NE: North East England, YH: Yorkshire and Humberside, Wa: Wales, WM: West Midlands, EE: East England, EM: East Midlands, SE: South East England, and SW: South West England. Adapted from Cho et al. (2012).

Focusing in on the future effects of atmospheric CO2, they note that the CERES-Wheat model simulated "only positive feedbacks from the physiological effects of increased atmospheric CO2 concentrations on crop growth and water use," in harmony with the earlier findings of Rosenzweig et al. (1994), adding that "in the absence of CO2 fertilisation, yield decreases may appear likely in some regions [italics added]."

Given such findings, it would appear that even the worst-case climate-change scenarios concocted by the world's climate modelers are insufficient to overpower the positive effects of atmospheric CO2 enrichment on country-wide winter wheat yields in the UK. And those positive effects will not be limited to this one crop in this one location, for the growth-enhancing benefits of atmospheric CO2 enrichment will enhance the future yields of all crops, everywhere!

Additional References
Jenkins, G.J., Murphy, J.M., Sexton, D.S., Lowe, J.A., Jones, P. and Kilsby, C.G. 2009. UK Climate Projections: Briefing Report. Met Office Hadley Centre, Exeter, UK.

Rosenzweig, C., Parry, M.L., Fischer, G. and Frohberg, K. 1994. Climate Change and World Food Supply. Research Report No. 3. Environmental Change Unit, University of Oxford, Oxford, UK.

Archived 21 May 2013