The collapse of Australia's rice production is one of several factors contributing to a doubling of rice prices in the last three months - increases that have led the world's largest exporters to restrict exports severely, spurred panicked hoarding in Hong Kong and the Philippines, and set off protests in countries including Cameroon, Egypt, Ethiopia, Haiti, Indonesia, Italy, Ivory Coast, Mauritania, the Philippines, Thailand, Uzbekistan and Yemen, the New York Times reported yesterday. Drought affects every agricultural industry based in Australia, not just rice - from shepherding, the other mainstay in this dusty land, to the cultivation of wine grapes, the fastest-growing crop here, with that expansion often coming at the expense of rice. The drought's effect on rice has produced the greatest impact on the rest of the world, so far. It is one factor contributing to skyrocketing prices, and many scientists believe it is among the earliest signs that a warming planet is starting to affect food production. It is difficult to definitely link short-term changes in weather to long-term climate change, but the unusually severe drought is consistent with what climatologists predict will be a problem of increasing frequency. The chief executive of the National Farmers' Federation in Australia, Ben Fargher, says: "Climate change is potentially the biggest risk to Australian agriculture." Drought has already spurred significant changes in Australia's agricultural heartland. Some farmers are abandoning rice, which requires large amounts of water, to plant less water-intensive crops like wheat or especially here in southeastern Australia, wine grapes. Other rice farmers have sold fields or water rights, usually to grape growers. Scientists and economists worry that the reallocation of scarce water resources - away from rice and other grains and toward more lucrative crops and livestock - threatens poor countries that import rice as a dietary staple. The global agricultural crisis is threatening to become political, pitting the United States and other developed countries against the developing world over the need for affordable food versus the need for renewable energy. Many poorer nations worry that subsidies from rich countries to support biofuels, which turn food, like corn, into fuel, are pushing up the price of staples. The World Bank and the United Nations Educational, Scientific and Cultural Organisation called on major agricultural nations to overhaul policies to avoid a social explosion from rising food prices. With rice, which is not used to make biofuel, the problem is availability. Even in normal times, little of the world's rice is actually exported - more than 90 per cent is consumed in the countries where it is grown. In the last quarter-century, rice consumption has outpaced production, with global reserves plunging by half just since 2000. A plant disease is hurting harvests in Vietnam, reducing supply. And economic uncertainty has led producers to hoard rice and speculators and investors to see it as a lucrative or at least safe bet. All these factors have made countries that buy rice on the global market vulnerable to extreme price swings. Senegal and Haiti each import four-fifths of their rice, and both have faced mounting unrest as prices have increased. Police suppressed violent demonstrations in Dakar on March 30, and unrest has spread to other rice-dependent nations in West Africa, notably Ivory Coast. The Haitian President, Ren, Pr,val, after a week of riots, announced subsidies for rice buyers on Saturday. Scientists expect the problem to worsen. The Intergovernmental Panel on Climate Change, set up by the United Nations, predicted last year that even slight warming would lower agricultural output in the tropics and subtropics. Moderate warming could benefit crop and pasture yields in countries far from the Equator, like Canada and Russia. In fact, the net effect of moderate warming is likely to be higher total global food production in the next several decades. But the scientists said the effect would be uneven, and enormous quantities of food would need to be shipped from areas farther from the Equator to feed the populations of often less-affluent countries closer to the Equator. The recent reports of the Intergovernmental Panel on Climate Change carried an important caveat that could make the news even worse: the panel said that existing models for the effects of climate change on agriculture did not yet include newer findings that global warming could reduce rainfall and make it more variable. Many agronomists contend that changes in the timing and amount of rain are more important for crops than temperature changes. Rajendra K. Pachauri, the chairman of the panel, said long-range climate forecasts for precipitation would require another five to 20 years of research. In addition to drought, climate change could also produce more extreme weather, more pest and weed outbreaks, and changes in sea level as polar ice melts. Most of the world's increase in rice production over the last quarter-century has occurred close to sea level, in the deltas of rivers like the Mekong in Vietnam, Chao Phraya in Thailand and Ganges-Brahmaputra in Bangladesh. Yet the effects of climate change are not uniformly bad for rice. Rising concentrations of carbon dioxide, the main greenhouse gas, can actually help rice and other crops - although the effect dwindles or disappears if the plants face excessive heat, inadequate water, severe pollution or other stresses. Still, the flexibility of farmers and ranchers Down Under has persuaded some climate experts that, particularly in developed countries, the effects of climate change may be mitigated, if not completely avoided. "I'm not as pessimistic as most people," said Will Steffen, the director of the Fenner School of Environment and Society at Australian National University. "Farmers are learning how to do things differently." (New York Times)