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Effects of Post-1980 Warming on Cropping Systems in China
Dong, J., Liu, J., Tao, F., Xu, X. and Wang, J. 2009. Spatio-temporal changes in annual accumulated temperature in China and the effects on cropping systems, 1980s to 2000. Climate Research 40: 37-48.

Climate alarmists have long contended that the earth experienced a warming over the past few decades that was unprecedented over the past millennium or more, while Dong et al. (2009) state that "the annual mean surface air temperature in China has increased 1.1C over the past 50 years," adding that "striking warming has occurred since the mid-1980s, particularly in northern China."

What was done
Noting that annual accumulated temperatures greater than 10C (AAT10) represent "an important indicator of thermal conditions in crop ecology (Qiu and Lu, 1980; Bai et al., 2008)," which "affects the choice of crop varieties, the crop calendar, cropping systems and crop patterns (Zheng et al., 2008)," the five Chinese scientists decided to "assess the relationship between accumulated temperature change and cultivated land use in China from the late 1980s to 2000," in order to determine the impact of the dramatic warming on the nation's agriculture.

What was learned
Dong et al. report that "since the late 1980s, AAT10 has noticeably risen in most of China." More specifically, they indicate that 1.22 x 1015 km2 of land moved from the potato accumulated temperature zone (ATZ) to the spring wheat ATZ, that 3.16 x 1015 km2 of land moved from the spring wheat ATZ to the winter wheat ATZ, and that 1.64 x 1015 km2 of land moved from the winter wheat ATZ to the rice ATZ. In addition, they determined that "because of improved thermal conditions since the late 1980s," farmers changed from a single crop per year to three crops in two years in many regions, while "the growth boundary of winter wheat moved northward."

What it means
With respect to the cropping index, which they define as the number of crops grown per year on a given area of land, the researchers from the Chinese Academy of Sciences state that "as a result of climate warming on a national scale, it is feasible for the cropping index to improve," and they report that, indeed, "cropping indices have improved in many regions since the 1980s," citing the studies of Yan et al. (2005) and Li et al. (2008). And because of this fact, they indicate that "to acquire higher yields of food and income, people have improved the cropping index in regions that had previously been difficult to crop and also in some areas where the index was low."

As a result, and in response to the past century's unprecedented increases in the twin evils of the radical environmentalist movement, it can be appreciated that rising levels of both the atmosphere's temperature and CO2 concentration have not in any way hurt the people of China. Quite to the contrary, in fact, they have actually improved the country's capacity to provide the great quantities of food needed to support its vast population.

Bai, Q.F., Huo, Z., Li, S., Du, H., He, N. and Jiang, Y. 2008. Comparison of accumulated temperature above 10C before and after the year 1978 in China. Chinese Journal of Applied Ecology 19: 1810-1816.

Li, J., Gao, P., Chen, Y.C., Chen, H. and Yang, T.M. 2008. Relationships between farming system and effective accumulated temperature in East China. Chinese Journal of Ecology 27: 361-368.

Qiu, B. and Lu, Q. 1980. A tentative regionalization of agroclimate of China. Acta Geographica Sinica 35: 116-125.

Yan, H., Liu, J. and Cao, M. 2005. Remotely sensed multiple cropping index variations in China during 1981-2000. Acta Geographica Sinica 60: 559-566.

Zheng, D., Ou, Y. and Zhou, C.H. 2008. Understanding of and thinking over geographical regionalization methodology. Acta Geographica Sinica 63: 563-573.

Reviewed 3 March 2010