Hurricane Isaac may have inundated the parishes of Louisiana, but for thousands of American farmers, it was a blessing, a reprieve from the most torrid summer on record.
In much of North America, July was the hottest month since such a record was first taken. Crop yields have fallen sharply; thousands of livestock have been lost.
The Midwest has suffered its worst drought in 56 years, and the International Grains Council has cut its forecast for the U.S. maize harvest by 25 million tons.
The relief from last week's rain may help planting conditions for winter wheat, but it's come too late to make much difference to summer crops. And it didn't even reach Iowa and Nebraska; 71% of Nebraska is now in "exceptional drought," the highest level on the scale.
On Thursday, the Federal Reserve of St. Louis reported that drought had ravaged farmers' income expectations in seven states, including Illinois and Missouri.
Although the drought was not discussed much at either party's convention, President Obama repeated his belief that our climate is changing.
"More droughts and floods and wildfires are not a joke. They're a threat to our children's future," he told the Democratic National Convention in Charlotte, North Carolina.
The farmers and ranchers of the American heartland are not alone. According to data from the National Oceanic and Atmospheric Administration, the land surface temperature in the Northern Hemisphere was the warmest ever in July, 2.14 degrees Fahrenheit higher than the average.
From Ukraine to Yellowstone, in Pakistan and Kazakhstan, the skies have stayed clear, and the earth has been parched. And on the world's commodity exchanges, the prices of corn, soybeans, wheat and tea are surging. The World Bank's food price index rose 10% in July.
Drought in the Black Sea region -- which includes the bread baskets of Ukraine, Russia and Kazakhstan -- has led to a sharp reduction in the forecast wheat harvest and pushed up export prices, putting further strain on the budgets of North African countries that import much of Russia's grain.
Russia expects its grain surplus for export to be 5 million tons lower than last year.
The three United Nations agencies involved in promoting food security warned this week, "We need to act urgently to make sure that these price shocks do not turn into a catastrophe hurting tens of millions over the coming months."
Far from the plains, there's also anxiety about the late and lame monsoon season in India and Pakistan. Rainfall in most places has been far below average, putting the new planting season at risk.
Ali Kachelo is the fifth generation of a farming family in Mirpur Khas, a farming district of Sindh province in Pakistan. His farm is famous for its mangoes, but drought this year has hurt his crops.
"Water being the source of all agriculture, the most valued input, we have been severely affected," he said. "Many farmers are losing money."
He recalls the devastating floods of 2010.
"This year, the agrarian economy is getting back on its feet after two years of devastating floods, and now the late monsoon has pushed us back into a terrible state."
The problem is compounded by ancient irrigation systems and corruption, with farmers often bribing local officials to be able to use more water.
But there is no "worldwide" drought threatening to wipe out crops everywhere. Indeed, 2010 and 2011 were the two wettest years on record if you measure global precipitation. The people of Bangkok and Jakarta need no reminding. Many Southeast Asian countries expect abundant rice crops.
The trouble is that rainfall is less reliable, especially in the Northern Hemisphere. Records over the past century show that peaks and troughs in rainfall, particularly north of the equator, have become sharper and bigger. It's either deluge or drought.
Years of drier weather in the U.S. plains have steadily reduced beef herds, with the number of calves down 8% since 2006 as pastures have dried out and feed costs have rocketed.
A return to food riots?
Thanks to new crop hybrids, irrigation and other technological advances, global food production has consistently risen despite the vagaries of weather patterns. But food security is skewed toward the developed world. In poorer countries, where a larger part of family income is spent on food, unpredictable harvests and volatile food prices can lead to social unrest.
A sudden increase in the price of staples in 2007 and 2008, in part due to adverse weather, led to riots in about a dozen countries.