Over 75 per cent of US corn and soybean crops were in areas hit by drought, he said, a national crisis.
Yesterday the Department of Agriculture said food prices would rise next year by 3 to 4 per cent.
Milk, eggs, beef, poultry and pork prices will all be hit by the drought, which has pushed up prices for feed.
As corn and soybean prices reach record highs, farmers in the US corn belt are faced with a stark choice: harvest emaciated crops or walk away.
Livestock farmers, unable to afford feed, are culling or selling stock. Ethanol plants are being closed. As borrowing soars, small rural communities brace for the economic fallout.
"I was home two weeks ago and saw the local corn was so short it hadn't produced ears," says Jim Kleinschmidt, rural communities programme director with the Institute for Agriculture and Trade Policy. His family farms cattle in northeast Nebraska, hard by the Missouri River.
"When you move around the corn belt there's different levels of height. But even when corn looks okay - when it's tall and green - often when you husk the ears there's no kernel. We're at the point when we're going to have more and more insurance adjusters out in the field."
This is a grim portent. Corn is the world's chief grain crop - exceeding wheat yields and almost double rice production - and is vital to the world's food supply. Eighty per cent of the US grain crop is corn and the Midwest dominates world production, with harvests exceeding the combined Chinese wheat and rice crop.
The drought follows an exceptionally warm winter, with little snow melt to moisten soil, and a mild spring.
Farmers anticipated a bumper corn crop and planted almost 39 million hectares, the biggest area in 75 years. A fast-growing, thirsty plant, corn is also delicate, unable to handle extreme heat and drought. Late last month temperatures in the southern corn belt soared, exceeding 40C for days on end as soil steadily dried out.
This proved fatal to pollination. Once temperatures climb above 35C corn becomes sterile. The crops wilted.
In May the Department of Agriculture's weekly crop bulletin rated 77 per cent of the corn crop as "good to excellent." By this week it had sunk to 26 per cent, a record low. The department said record highs had expanded into the western corn belt, withering corn and soybeans at the pollination stage, just as it had across the lower Midwest in late June and early July.
"This is dramatic," says Kleinschmidt. "We don't only look at this in a US context. This is part of an overall global crisis." Recent droughts striking soybeans, corn and wheat in Brazil, Argentina, Russia, Ukraine and Australia emphasise the fragility of food security in petroleum-based monocultures that have abandoned less profitable but more sustainable farming techniques.
Fragility is translated via the commodities market: a poor US corn harvest can push up the price of Australian grain, while triggering shortages in poorer food importing nations with scant currency reserves. Smaller food inventories raise the pressure. The US has atrophied its public grain reserves, down to 2.7 million bushels in 2008, to make farmers respond to the market.
Although the USDA says this year's corn harvest is still just shy of a record tonnage two years ago, and foreign growers expect higher commodity returns as they fill the market gap, such short-term thinking fails to address the deeper problems signalled by the spreading drought.
A century ago farmers on the Great Plains, which include the corn belt, tilled the prairies under the illusion that "rain follows the plough". Soil moisture was lost, precipitating the 1930s Dust Bowl, an epic drought.
Hubris may lurk behind this year's drought, an extreme weather event scientists say is consistent with human-induced climate change. Agriculture has evolved over 11,000 years, during which climate has been remarkably stable. Can agriculture adapt to a changing climate?
"It's really about the rate and extent of change and how it impacts soil moisture and other issues," says Alden Meyer, director of strategy and policy with the Union of Concerned Scientists. "Compared to our ancestors millennia ago we are much more adept at using technology, plant breeding and other strategies to try and deal with change. But how far ahead of the curve can we stay?"
Earth Policy Institute president Lester Brown believes hunger can be cut only if runaway population growth and energy and water shortages are addressed, a link he discusses in a new book, Full Planet, Empty Plates.
"Suddenly that climate system is changing. With past droughts or floods things went back to normal in a few years. Now there's no norm for farmers to return to."
Could the great drought of 2012 be a tipping point in US attitudes towards climate change? While the media is skittish about making causative narratives that link specific weather events to global warming, a nationwide poll this month by the University of Texas found 70 per cent of respondents believe the climate is changing.
"I don't think most people understand the difference between 350 and 390 parts per million of carbon dioxide in the atmosphere," says Brown. "That goes right by them. But they do understand check-out prices."
Dramatic food price hikes have long fed social unrest. It is anyone's guess what will happen when the effects of the heartland drought ripple through the international commodity market in an already jittery world economy.
CRANKING UP THE HEAT
2012
is the hottest year in the United States since National Oceanic and Atmospheric Administration records began in 1895
88 per cent
of the corn crop hit by drought
4-5 per cent
rise in beef prices expected next year
3.5-4.5 per cent
rise in dairy products forecast, 3-4 per cent eggs, 2.5-3.5 per cent pork
AP, New York Times
