鹿的危机作文500字篇21

half of the worlds population could face food shortages by the end of this century due to climate change, a new study warned thursday。

according to researchers, there is a 90 percent probability that by 2100 the minimum temperatures in the tropics and sub-tropical regions will be higher than the maximums so far recorded in those areas。

the effect on crop-growing in those regions would be dire, according to the projections based on direct observations and data culled from 23 computer models on the planets evolving climate patterns。

"the stresses on global food production from temperature alone are going to be huge, and that doesnt take into account water supplies stressed by the higher temperatures," said david battisti, a university of washington atmospheric sciences professor。

in the tropics, the warmest temperatures will cut maize and rice harvests by 20 to 40 percent, the researchers said。

the hotter weather will also reduce the moisture in the soil, cutting yields even further。

some three billion people, or half the worlds population, currently live in tropical and sub-tropical regions, and their number is set to double by the end of the century。

these regions stretch from northern india, southern china to much of australia and all of africa, and also extend from the southern united states to northern argentina and southern brazil。