FALTERING British efforts to tackle Afghanistan's poppy crop have found an unlikely ally – in the weather.
Freak winter weather linked to global warming is expected to decimate parts of the country's opium harvest.
Scientists believe freezing temperatures followed by late rains and a possible drought could slash this year's yields. Some farmers could
suffer up to 50 per cent losses. The fierce cold – which claimed hundreds of lives across Afghanistan – is thought to have stopped millions of poppy seeds from germinating, while late rains and a meagre snow melt following an unusually low snowfall have stunted many of the plants that survived.
One expert said: "It was too cold in some areas for the seeds to come alive. Between 30 per cent and 50 per cent of the seeds may not have germinated."
Survey teams are scouring the country's poppy fields to get precise data on this season's plants. Privately, UN officials and European diplomats both predict a drop in yields.
Poppy is more resistant to drought than food crops, but a water shortage at a key stage in the plant's life cycle is expected to stunt the size of the seed pods. Farmers harvest a sap from the pods to make opium, which in turn is used for heroin.
"The more water, the more opium," said Asif Zaidi, the head of the United Nations' environment programme. "This year was exceptionally cold, followed by low rainfall. Some of the crop will be destroyed. But what extent we don't yet know."
The poppy farmers worst affected by this year's weather are those who planted in November, after the cold spell set in. That includes about half of Helmand's poppy farmers, and a third of growers nationwide. Other farmers were unable to plant on time because their fields froze.
Satellite images taken earlier this year showed the poppy-growing area was roughly the same as last year, which had perfect growing conditions. The UN had predicted the harvest would be the same.
But Afghanistan's dry climate is especially susceptible to climate change, Mr Zaidi said. "Minor climatic changes result in major impacts," he added. "There are definitely changes taking place in Afghanistan, but at the moment, most of the evidence is anecdotal."
This winter was so cold there was less snow than usual. Most of the country's rivers are fed by meltwater from the Hindu Kush mountain range.
Meanwhile, the spring rains, which usually come in late February, arrived in April, long after the poppy seedlings started a key growth spurt.
Poppy is a winter crop. It is normally planted before the frosts and the seeds germinate before the cold weather. They sit dormant through the winter, then shoot up in the spring.
Afghanistan's minister of agriculture, Obaidullah Ramin, blamed global warming. Small changes in global temperatures tip weather cycles to extremes of hot and cold, he said. "One hundred per cent this is a result of climate change and global warming. The climate is changing all over the world, but it has more impact here because we have less control over nature," he added.
"Afghanistan is a very dry part of the world. Small changes in temperature are exacerbated."
The best poppy-growing land, in Helmand, is fed by irrigation canals from the Helmand River. But many of the country's canals were destroyed during decades of fighting. In poorer areas farmers grow poppies on rain-fed land, which is beyond the reach of rivers and not good enough to sustain food crops.
The drop in poppy yields is unlikely to affect heroin supply on Britain's streets. Experts estimate there is at least seven years' supply in transit from the fields to the users, while some farmers have stockpiled their own opium because of a drop in farm-gate prices.
