From the New York Times, excerpts of a long story by Justin Gillis, "A Warming Planet Struggles to Feed Itself":
The rapid growth in farm output that defined the late 20th century has slowed to the point that it is failing to keep up with the demand for food, driven by population increases and rising affluence in once-poor countries.
Consumption of the four staples that supply most human calories — wheat, rice, corn and soybeans — has outstripped production for much of the past decade, drawing once-large stockpiles down to worrisome levels. The imbalance between supply and demand has resulted in two huge spikes in international grain prices since 2007, with some grains more than doubling in cost.
Those price jumps, though felt only moderately in the West, have worsened hunger for tens of millions of poor people, destabilizing politics in scores of countries, from Mexico to Uzbekistan to Yemen. The Haitian government was ousted in 2008 amid food riots, and anger over high prices has played a role in the recent Arab uprisings.
Now, the latest scientific research suggests that a previously discounted factor is helping to destabilize the food system: climate change. . . .
A scramble is on to figure out whether climate science has been too sanguine about the risks. Some researchers, analyzing computer forecasts that are used to advise governments on future crop prospects, are pointing out what they consider to be gaping holes. These include a failure to consider the effects of extreme weather, like the floods and the heat waves that are increasing as the earth warms.
A rising unease about the future of the world’s food supply came through during interviews this year with more than 50 agricultural experts working in nine countries.
These experts say that in coming decades, farmers need to withstand whatever climate shocks come their way while roughly doubling the amount of food they produce to meet rising demand. And they need to do it while reducing the considerable environmental damage caused by the business of agriculture. . . .
When Norman E. Borlaug, a young American agronomist, began working here in the 1940s under the sponsorship of the Rockefeller Foundation, the Yaqui Valley farmers embraced him. His successes as a breeder helped farmers raise Mexico’s wheat output sixfold.
In the 1960s, Dr. Borlaug spread his approach to India and Pakistan, where mass starvation was feared. Output soared there, too.
Other countries joined the Green Revolution, and food production outstripped population growth through the latter half of the 20th century. Dr. Borlaug became the only agronomist ever to win the Nobel Peace Prize, in 1970, for helping to “provide bread for a hungry world.”
As he accepted the prize in Oslo, he issued a stern warning. “We may be at high tide now,” he said, “but ebb tide could soon set in if we become complacent and relax our efforts.”
As output rose, staple grains — which feed people directly or are used to produce meat, eggs, dairy products and farmed fish — became cheaper and cheaper. Poverty still prevented many people in poor countries from buying enough food, but over all, the percentage of hungry people in the world shrank.
By the late 1980s, food production seemed under control. Governments and foundations began to cut back on agricultural research, or to redirect money into the problems created by intensive farming, like environmental damage. Over a 20-year period, Western aid for agricultural development in poor countries fell by almost half, with some of the world’s most important research centers suffering mass layoffs.
Just as Dr. Borlaug had predicted, the consequences of this loss of focus began to show up in the world’s food system toward the end of the century. Output continued to rise, but because fewer innovations were reaching farmers, the growth rate slowed.
That lull occurred just as food and feed demand was starting to take off, thanks in part to rising affluence across much of Asia. Millions of people added meat and dairy products to their diets, requiring considerable grain to produce. Other factors contributed to demand, including a policy of converting much of the American corn crop into ethanol.
And erratic weather began eating into yields. A 2003 heat wave in Europe that some researchers believe was worsened by human-induced global warming slashed agricultural output in some countries by as much as 30 percent. A long drought in Australia, also possibly linked to climate change, cut wheat and rice production.
In 2007 and 2008, with grain stockpiles low, prices doubled and in some cases tripled. Whole countries began hoarding food, and panic buying ensued in some markets, notably for rice. Food riots broke out in more than 30 countries.
Farmers responded to the high prices by planting as much as possible, and healthy harvests in 2008 and 2009 helped rebuild stocks, to a degree. That factor, plus the global recession, drove prices down in 2009. But by last year, more weather-related harvest failures sent them soaring again. This year, rice supplies are adequate, but with bad weather threatening the wheat and corn crops in some areas, markets remain jittery. . . .
Forty years ago, a third of the population in the developing world was undernourished. By the tail end of the Green Revolution, in the mid-1990s, the share had fallen below 20 percent, and the absolute number of hungry people dipped below 800 million for the first time in modern history.
But the recent price spikes have helped cause the largest increases in world hunger in decades. The Food and Agriculture Organization of the United Nations estimated the number of hungry people at 925 million last year, and the number is expected to be higher when a fresh estimate is completed this year. The World Bank says the figure could be as high as 940 million. . . .
For decades, scientists believed that the human dependence on fossil fuels, for all the problems it was expected to cause, would offer one enormous benefit.
Carbon dioxide, the main gas released by combustion, is also the primary fuel for the growth of plants. They draw it out of the air and, using the energy from sunlight, convert the carbon into energy-dense compounds like glucose. All human and animal life runs on these compounds.
Humans have already raised the level of carbon dioxide in the atmosphere by 40 percent since the Industrial Revolution, and are on course to double or triple it over the coming century. Studies have long suggested that the extra gas would supercharge the world’s food crops, and might be especially helpful in years when the weather is difficult.
But many of those studies were done in artificial conditions, like greenhouses or special growth chambers. For the past decade, scientists at the University of Illinois have been putting the “CO2 fertilization effect” to a real-world test in the two most important crops grown in the United States. . . .
Their work has contributed to a broader body of research suggesting that extra carbon dioxide does act as plant fertilizer, but that the benefits are less than previously believed — and probably less than needed to avert food shortages. “One of the things that we’re starting to believe is that the positives of CO2 are unlikely to outweigh the negatives of the other factors,” said Andrew D. B. Leakey, another of the Illinois researchers.
Other recent evidence suggests that longstanding assumptions about food production on a warming planet may have been too optimistic. . . . This line of research suggests that in the type of climate predicted for the United States by the end of the century, with more scorching days in the growing season, yields of today’s crop varieties could fall by 30 percent or more.
Though it has not yet happened in the United States, many important agricultural countries are already warming rapidly in the growing season, with average increases of several degrees. A [new paper suggests] that temperature increases in France, Russia, China and other countries were suppressing crop yields, adding to the pressures on the food system. “I think there’s been an under-recognition of just how sensitive crops are to heat, and how fast heat exposure is increasing,” Dr. [David] Lobell said. . . .
William E. Easterling, dean of earth sciences at Pennsylvania State University and a primary author of the 2007 [IPCC] report, said in an interview that the recent research had slightly altered his perspective. “We have probably to some extent overestimated” the benefits of carbon dioxide in computerized crop forecasts, he said. But he added that applying a “correction factor” would probably take care of the problem, and he doubted that the estimates in the report would change drastically as a result.
The 2007 report did point out a hole in the existing body of research: most forecasts had failed to consider several factors that could conceivably produce nasty surprises, like a projected rise in extreme weather events. No sooner had the report been published than food prices began rising, partly because of crop failures caused by just such extremes. . . .
Perhaps the most hopeful sign nowadays is that poor countries themselves are starting to invest in agriculture in a serious way, as many did not do in the years when food was cheap.
In Africa, largely bypassed by the Green Revolution but with enormous potential, a dozen countries are on the verge of fulfilling a promise to devote 10 percent of their budgets to farm development, up from 5 percent or less.
“In my country, every penny counts,” Agnes Kalibata, the agriculture minister of Rwanda, said in an interview. With difficulty, Rwanda has met the 10 percent pledge, and she cited a terracing project in the country’s highlands that has raised potato yields by 600 percent for some farmers.
Yet the leading agricultural experts say that poor countries cannot solve the problems by themselves. The United Nations recently projected that global population would hit 10 billion by the end of the century, 3 billion more than today. Coupled with the demand for diets richer in protein, the projections mean that food production may need to double by later in the century.
Unlike in the past, that demand must somehow be met on a planet where little new land is available for farming, where water supplies are tightening, where the temperature is rising, where the weather has become erratic and where the food system is already showing serious signs of instability.
“We’ve doubled the world’s food production several times before in history, and now we have to do it one more time,” said Jonathan A. Foley, a researcher at the University of Minnesota. “The last doubling is the hardest. It is possible, but it’s not going to be easy.”