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SCIENCE: Climate Change Cutting Crops, Warn Researchers

Stephen Leahy

BROOKLIN, Canada, Sep 19 2003 (IPS) - World cereal stocks are plunging to their lowest levels in recent history and might not recover due to climate change, experts say.

“This year’s world grain harvest is falling short of consumption by 93 million tons, dropping world grain stocks to the lowest level in 30 years,” says Lester R. Brown, president of the Earth Policy Institute, a Washington, D.C.-based research group.

“As rising temperatures and falling water tables hamstring farmers’ efforts to expand production, prices of wheat and rice are edging upward,” he added in an interview with IPS.

Record heat and declining water supplies are being blamed for reduced grain harvests the past three years, including a record shortfall in 2002 of 96 million tons.

Combined with this year’s anticipated shortfall, the Food and Agriculture Organisation (FAO) forecast the world’s cereal stocks will be reduced 20 percent to 372 million tonnes, their lowest levels in three decades.

This year’s harvest is estimated to be 1,818 million tons, with wheat expected to account for the largest share of the overall decline. The harvest suffered primarily because Europe’s heat wave reduced that continent’s production by at least 25 million tonnes.

The heat wave started in early summer, when Switzerland, in the heart of Europe, experienced its hottest June since record keeping began 140 years ago. In July, temperatures soared across the rest of the continent.

The damage has been most severe in Eastern Europe, which is now bringing in its worst wheat crop in three decades. The Ukraine’s harvest has dropped from 21 million tons last year to five million tons, while Romania has its worst crop on record.

The FAO also predicts declines in Asia and in Central America, where lack of irrigation water in Mexico is to blame.

Grain production has not increased in the past eight years, and since 1999, the world has eaten more grain than it has produced. While carryover stocks should be sufficient for next year, prices for wheat, rice and soybean are already rising.

If 2004 brings another large harvest shortfall, there could be chaos in world grain markets by this time next year, predicts Brown.

He believes there have been enough extreme weather events – including record high temperatures – in the last decade to suggest that climate change is beginning to take its toll on agriculture.

But Brown admits there is no direct proof that climate change – primarily seen in the rising temperatures that most experts accept are caused by growing amounts of greenhouse gases in the atmosphere, produced from burning oil, coal and natural gas – is responsible for the poor harvests over the past few years.

Yet, “we can’t wait to do something until we know for certain because it will be too late,” says Brown.

More frequent, long-lasting hot and dry spells are expected because of climate change, says Barry Smit, research chair in global environmental change at the University of Guelph, west of Toronto.

While there is not enough evidence to statistically link recent droughts and grain shortfalls to climate change, it would take another 150 years of data to prove the connection with a high degree of certainty, he adds.

But the risks have already increased for farmers, Smit adds. ”Where drought may in the past have occurred once out of 20 years, it may now strike every ten or every five years.”

”Current shortages in grain production are likely enhanced by climate change,” he says.

The U.S. non-governmental organisation (NGO) Worldwatch Institute reports that in some recent estimates, 20 percent of the increase in water scarcity in coming decades will be caused by climate change.

”In poor countries, the consequences of climate change could be dire – erratic weather patterns have already been the primary cause of famine for millions around the world,” according to an Institute news release.

During the 1990s, many global studies on the impact of climate change on agriculture generally predicted positive impacts in northern areas due to longer growing seasons, along with declines in the south because of increased temperatures.

But it was believed that increases in plant-stimulating carbon dioxide (CO2) emissions – the principle greenhouse gas – would offset those losses, producing a net gain for global agriculture.

Those studies made some simplistic assumptions, says Smit.

Agriculture cannot expand much in Canada’s north, for example, because the soils are poor. And in order to benefit from increased C02, plants will need more water which may not be available.

The International Panel on Climate Change (IPCC) concluded in 2001 that agricultural yields would fall even in tropical and semi-tropical regions of Africa and Latin America because of warmer temperatures.

Since then, research at the Consultative Group on the International Agricultural Research (CGIAR), the U.S. Department of Agriculture and the International Rice Research Institute have found that grains such as rice are very sensitive to rises in temperature.

For example, if temperatures are 3 or 4C above normal during the two weeks when rice flowers, fertilisation and, consequently, rice production, falls dramatically. Similar results were found with soy.

It is possible that the world is approaching a threshold in agriculture where the combination of rising temperatures, soil erosion, disease and insects override advances in agricultural technology, Brown speculates.

More certain and more immediate is the growing water shortage in the major grain-producing countries of China, India, the United States and Canada.

Water tables are falling every year in these regions as demand, mainly for irrigation continues to climb. This unsustainable pumping – with wells being drilled ever deeper – means much less water will be available in 50 years.

Brown believes that major global efforts are required to derail the coming food security crisis and outlines them in a new book, ‘Plan B: Rescuing a Planet Under Stress and a Civilization in Trouble’.

They include improving efficiency in water usage. It currently takes 1,000 tons of water to produce one ton of grain, but methods exist, such as drip irrigation and drought-tolerant grain varieties, to reduce that amount, although they cost more, he says.

With rising temperatures imperilling food supply, serious reductions of greenhouse gases from the production of fossil fuels are also needed. These will have to go far beyond the global goals of the Kyoto Protocol – a five percent cut in carbon emissions by 2012 – Brown predicts.