Extreme heat around the world is seriously threatening agriculture and food systems, the United Nations has warned. Excessive heat is stopping farmers from working in the fields, putting livestock under severe stress and cutting crop output, putting the livelihoods of more than a billion people at risk.

Experts say increasingly intense and frequent heatwaves, on both land and sea, are pushing food supplies in some regions almost "to the brink of collapse". The findings come from a major report prepared jointly by the Food and Agriculture Organization (FAO) and the World Meteorological Organization (WMO).

According to the report, in hot regions it could become almost impossible for farmers to work safely outdoors for up to 250 days a year, meaning they would be unable to work for two-thirds of the year. These regions include South Asia, among them large parts of India, tropical sub-Saharan Africa and vast areas of Central and South America.

The situation is also becoming dire for livestock. Heat stress in ordinary animals begins at about 25C, and death rates are rising. Excess heat reduces milk output in dairy cows and lowers the fat and protein content of milk. Animals such as chickens cannot sweat, so as temperatures rise they face the risk of digestive breakdown, organ failure and heart-related shock.

Output of most crops starts to fall above 30C. Cell walls weaken and toxic substances can form. Maize output has fallen by about 10 per cent in some regions, and wheat by about the same rate, which is expected to fall further if temperatures rise more than 1.5C above pre-industrial levels.

Marine heatwaves are also becoming deadly for fish. As dissolved oxygen in the water falls, fish are dying in large numbers and populations are shrinking.

The report says that because heatwaves are often predictable, much more can be done to warn farmers in advance, through weather forecasts and mobile phone messages about extreme weather.

Richard Waite, director of agriculture initiatives at the World Resources Institute, said action to adapt to rising temperatures is needed now. Farmers must be given the equipment, knowledge and early warnings they need to cope with extreme weather.

He warned that without adaptation, extreme heat will cut crop and livestock output. More land would then have to be brought under farming to keep food production going, which through land-use change would raise emissions further and worsen the climate's effects on agriculture. "The opposite is needed," he said: solutions that help farmers maintain output and raise it sustainably must be scaled up.

Another analyst, Morgan Ody, said working people's lives are at risk. Farmers, farmworkers and small-scale fishers, especially women and older people, are most vulnerable to extreme heat. Such extreme weather is largely driven by industrial monoculture farming and livestock systems, which emit large amounts of greenhouse gas, she said.

Ody called for compensation for affected workers, debt relief, public investment in adaptation and rules to protect workers. How long workers in fields or on boats have to spend in the heat should be set, and employers should be required to provide shade, rest and water, she said. In the long term she also spoke of a shift to environmentally friendly farming methods.

Experts say the modern industrialised food system relies on a very small number of staple crops and is heavily dependent on fertiliser and other inputs, which makes it vulnerable and less able to absorb shocks such as extreme heat.

Molly Anderson, professor of food studies at Middlebury College in Vermont, United States, said food systems must become more diverse so they can withstand shocks. Intensive farming has reduced trees, shade and the mix of crops and animals in many places, and these must be brought back, she said.

She warned that the risk of several crops failing at once during extreme heat could have major effects on food prices, supply chains and the economy. Adaptation also has limits, she said; in the long term the only solution is to cut fossil fuel use, move quickly to renewable energy and invest heavily in adaptation.

Tim Lang, professor of food policy at the University of London, said hot countries would be hit hardest, but temperate regions and developed countries are not exempt. The rapid growth of climate uncertainty is creating a terrible challenge for food producers worldwide.

He said the British Isles are not immune either. "The areas we get food from will dry up. Land use here will change. Dependence on water will be exposed. Crops that started well will not survive. Production will be disrupted. The regular patterns of production and consumption will be forced to change. Those who think climate change will not affect us should think again."

The Bengali report cited The Guardian as its source.

Source: Jagonews24. First published in Bengali on The Agro News.