to great changes in the climate of the northern hemisphere, possible resulting in an alteration of the earth's chief food-growing zones。因为 carbon dioxide导致raise the temperature of the earth's surface，那当然也可能导致great changes in the climate。也就是说单单从短文的角度来说选项C是正确的，不过短文中的great changes in the climate却是未来的推测，不是现时的影响，所以选项C是一个似是而非不符合题意的选项，错。

责任编辑:gaoyan