Impact of global warming on crop yield

Based on the 2050 climate scenario simulated by three GCMs (GFDL, MPI, and UKMO-H) (Wang, 2002), the effect of climate change on the crop yield was investigated by using three revised crop models (ORIZA1-rice, CERES-wheat and CERES-maize models) which were more suitable to simulate the influence of climate change on Chinese agriculture. The predicted ranges of crop yield are listed in Table 11.4. It is seen that the yield of three main crops will decrease by 5% ~ 10% by 2050.

Table 11.4 The predicted change of crop yield under the climate scenario of 2050 (%)

Crop type

Yield Range (%)

Average (%)

Rain fed winter wheat

-0.2 ~ -23.3

-7.7

Irrigated winter wheat

-1.6 ~ -2.5

-2.0

Rain fed spring wheat

-19.8~ -54.9

-31.4

Irrigated spring wheat

-7.2 ~ -29.0

-17.7

Early rice

-1.9 ~ -5.2

-3.7

Late rice

-8.8 ~-12.9

-10.4

Single-cropping rice

-8.0 ~-13.7

-10.5

Rain fed spring maize

-19.4 ~ +5.3

-

Irrigated spring maize

-8.6 ~ +3.6

-

Rain fed summer maize

-11.6 ~ -0.7

-

Irrigated summer maize

-11.6 ~ +0.7

-

As shown in Table 11.4, the effects of global warming on the crop yield of China will be generally negative except some specific crops. All the yield of early rice, late rice and single-cropping rice will decrease without considering moisture condition. The yield of late rice and single-cropping rice will decrease by more than 8%, whereas the decrease in the yield of early rice will be relatively smaller. The warming climate causes a decreasing trend in the wheat yield. The most evident decrease (up to 30%,) will be the rain fed spring wheat, whereas, the decrease in the yield of irrigated spring wheat, rain fed winter wheat, and irrigated winter wheat will be 17%, 7%, and 2%, respectively. The influences of global warming on maize yield basically appear to be negative. The warming climate will result in decrease of the yield by 2% ~ 7%, 5% ~ 7 %, 2% ~ 6%, 6% ~ 7 %, for the spring maize, the summer maize, the irrigated maize, and the maize without irrigation, respectively. Therefore, the climate change will induce decrease of maize average productivity by 3% ~ 6 % in China. The de crease in irrigated maize productivity will be less than that in rain cultivated maize.

The impact of climate change on crop yield will be different from region to region. For instance, the most evident decrease (about 17%) in the single-cropping rice productivity occurs in central northern areas of the North China, while the crop productivity are decreased by 10% ~ 15%, 6% ~ 10%, in middle and lower reaches of the Yellow River, and in Yangtze-Huaihe river basin, respectively. In the southern rice areas to the south of the Yangtze River, the decrease of the late rice productivity are 10% ~ 15%, 7% ~ 10% in the northwestern areas, and in the southeastern areas, respectively.

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