Global warming will allegedly reduce crop yield by 30 percent!

More alarmist idiocy here:

New Delhi, March 12 (IANS) Global warming will lead to 30 percent reduction in crop harvest and increase child mortality due to diarrhoea, parliament was informed Wednesday.

Once again: the globe is probably warmer now than it was in 1850 or 1976. Have we observed actual massive reductions in crop harvest?