The rapidly warming global climate is likely to seriously alter crop yields in the tropics and subtropics by 2100, leaving half the world’s population facing serious food shortages, according to new research released this week.
To compound matters, the population of this equatorial belt – from about 35 degrees north latitude to 35 degrees south latitude – is among the poorest on Earth and is growing faster than anywhere else.
“The stresses on global food production from temperature alone are going to be huge, and that doesn’t take into account water supplies stressed by the higher temperatures,” said David Battisti, a University of Washington atmospheric sciences professor.
It will take a number of decades to develop and produce different varieties that are better adapted for warmer climates, according to Rosamond Naylor, director of Stanford University’s Program on Food Security and the Environment.  “This is a compelling reason for us to invest in adaptation,” Naylor said.  ”We are taking the worst of what we’ve seen historically and saying that in the future it is going to be a lot worse unless there is some kind of adaptation.”
The serious climate issues won’t be limited to the tropics, the scientists conclude. An example cited is the record temperatures that struck Western Europe in June, July and August of 2003, killing an estimated 52,000 people. The summer-long heat wave in France and Italy cut wheat yields and fodder production by one-third. In France alone, temperatures were nearly 6.5 degrees Fahrenheit above the long-term mean, and the scientists say such temperatures could be normal for France by 2100.
In the tropics, the higher temperatures can be expected to cut yields of the primary food crops, maize and rice, by 20 to 40 percent, the researchers said. But rising temperatures also are likely to have a serious impact on soil moisture, cutting yields even further.
Currently 3 billion people live in the tropics and subtropics, and their number is expected to nearly double by the end of the century. The area stretches from the southern United States to northern Argentina and southern Brazil, from northern India and southern China to southern Australia and all of Africa.
The scientists said that many who now live in these areas subsist on less than $2 a day and depend largely on agriculture for their livelihoods.
“When all the signs point in the same direction, and in this case it’s a bad direction, you pretty much know what’s going to happen,” Battisti said. “You are talking about hundreds of millions of additional people looking for food because they won’t be able to find it where they find it now. You can let it happen and painfully adapt, or you can plan for it,” he said.
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