riots in the streets of Mozambique over sharply higher food prices have left 13 dead. Anger is growing in Egypt and Serbia as well. Panicked Russian shoppers have cleared the shelves of staple grains. And the devastating floods that have left as many as 10 million Pakistanis homeless are also raising concerns about the country's ability to feed itself.
A series of isolated disasters? Not at all. The common thread: extreme weather, which is putting pressure on food supplies around the globe.
What's going on?
For most of the summer, Russia was in the grip of an unprecedented heat wave. Fires darkened the skies of Moscow with thick smoke, and the Russian wheat crop withered and burned. Fully a third of the usual Russian harvest of buckwheat -- one of the country's most commonly used grains -- was lost. That has led to shortages of wheat at home in Russia -- and an export ban on Russian wheat.
The export cutback has in turn driven up food prices in countries like Mozambique and Egypt, which depend on food imports, sparking anger and riots.
Meanwhile, the same weather pattern of high pressure that brought searing heat to Russia diverted moisture in the atmosphere toward Pakistan, causing torrential rains and devastating flooding.
Who is affected?
Mostly, just those people in countries now facing shortages and price spikes. There's no overall shortage of food. The United Nations' Food and Agriculture Organization says that 2010 brought the third-largest harvest of grains on record, leaving global food stocks high.
But the shortfall in Russian wheat did push up grain prices. As a result, the government of Mozambique raised the official price of bread by 20%. That touched off the riots, forcing the government to backtrack.
In hard-hit Pakistan, prices of food have risen 15%.
[Related: Pakistan floods: How to help]
The Food and Agriculture Organization acknowledges that higher prices are causing hardships. But it adds that the situation now is far less dire than it was in 2007-08, when the soaring price of energy caused an even bigger spike in food prices.
Will the United States be affected?
In the short term, there are few concerns outside countries hit by natural disasters or higher prices. Even Russians aren't facing actual shortages of food, just limited supplies of one of their favorite staples -- buckwheat.
In fact, the problems have been a boon for American farmers. Exports of farm products nearly hit record levels in 2010, thanks to bountiful harvests and higher prices for wheat, corn, cotton and other crops.
How worried should we be?
Nevertheless, the long-term threat -- the potential impact of climate change on agriculture throughout the globe -- is major. Until recently, scientists were careful to say that any single natural disastrous climate event, such as the Russian drought or Hurricane Katrina, could not be attributed to global warming. No longer. "The issue isn't whether these events are natural or caused by climate change," former Energy Department official Joseph J. Romm told Yahoo! News. "It's both. You can't separate the two."
For instance, a study by Kevin Trenberth -- head of climate analysis at the National Center for Atmospheric Research in Boulder, Colo. -- has shown that Hurricane Katrina dumped more rain on the Gulf Coast than would have happened without climate change.
"What we can say is that certain events would have been extremely unlikely to have occurred without global warming, and that includes the Russian heat wave and wildfires, and Pakistan, Chinese and Indian floods," Trenberth told Yahoo! News.
[Related: Farmer's Almanac: Global cooling to continue]
Even the Russians have become believers in the threat. The Russian government used to doubt the existence of climate change, or argue that it might be beneficial for Russia to get a bit warmer.
Now, suggests Romm, they've realized that global warming won't bring a gradual and relatively benign increase in temperatures. Instead, as scientists' climate models have long predicted, the effect will be to intensify extreme events. As Russian President Dmitri A. Medvedev told the Russian Security Council this month: "Everyone is talking about climate change now. Unfortunately, what is happening now in our central regions is evidence of this global climate change, because we have never in our history faced such weather conditions in the past."
How critical could the situation get?
If you think the Russian heat wave or Pakistan floods are bad, wait until the Earth's temperature rises a few more degrees, as scientists' models also predict. "We ain't seen nothing yet," warns Romm. "I think we can't even imagine" future events.
So agriculture -- and the world's ability to feed itself -- face huge challenges.
"We are getting to a point where we are getting more water, more rainy days, but it's more variable, so it leads to droughts and it leads to floods," Sunita Narain, the head of the Center for Science and Environment in India, told AFP during a world conference on water, being held through Saturday in Sweden. "That is leading to huge amounts of stress on agriculture and livelihoods."
What can be done to ease the problems?
When it comes to short-term problems -- shortages and high prices -- the key is to ensure that global food stocks get to the countries that most need them, agricultural experts say.
The long-term problem is far more complicated. The only real solution, many scientists believe, is to tackle global warming at its root, by reducing emissions from fossil fuels or by stepping up efforts to take carbon dioxide and other greenhouse gases out of the atmosphere.
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