UN specialists are to look again at the contribution of meat production to climate change, after claims that an earlier report exaggerated the link.

联合国专家正准备重新调查肉类生产与气候变化之间的关系，因为有人宣称之前的报告夸大了二者之间的联系。

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Livestock's Long Shadow calculated meat-related emissions from field to abattoir³

A 2006 report concluded meat production was responsible for 18% of greenhouse gas emissions - more than transport.

The report has been cited（引用，引证） by people campaigning for a more vegetable-based diet, including Sir Paul McCartney.

But a new analysis, presented at a major US science meeting, says the transport comparison was flawed.

Sir Paul was one of the figures launching a campaign late last year centred on the slogan "Less meat = less heat".

But curbing⁴ meat production and consumption would be less beneficial for the climate than has been claimed, said Frank Mitloehner from the University of California at Davis (UCD).

"Smarter animal farming, not less farming, will equal less heat," he told delegates to the American Chemical Society (ACS) meeting in San Francisco.

"Producing less meat and milk will only mean more hunger in poor countries."

Leading figures in the climate change establishment, such as Intergovernmental Panel on Climate Change (IPCC) chairman Rajendra Pachauri and Lord (Nicholas) Stern, have also quoted the 18% figure as a reason why people should consider eating less meat.

Apples and pears

The 2006 report - Livestock's Long Shadow, published by the UN Food and Agriculture Organization (FAO) - reached the figure by totting up all greenhouse-gas emissions associated with meat production from farm to table, including fertiliser production, land clearance⁵, methane⁶（沼气，甲烷） emissions from the animals' digestion⁷, and vehicle use on farms.

But Dr Mitloehner pointed⁸ out that the authors had not calculated transport emissions in the same way, instead just using the IPCC's figure, which only included fossil fuel（矿物燃料） burning.

"This lopsided（不平衡的） 'analysis' is a classical apples-and-oranges analogy that truly confused the issue," he said.

One of the authors of Livestock's Long Shadow, FAO livestock policy officer Pierre Gerber, told BBC News he accepted Dr Mitlohner's criticism.

"I must say honestly that he has a point - we factored in（纳入） everything for meat emissions, and we didn't do the same thing with transport," he said.

"But on the rest of the report, I don't think it was really challenged."

FAO is now working on a much more comprehensive analysis of emissions from food production, he said.

It should be complete by the end of the year, and should allow comparisons between diets, including meat and those that are exclusively（专有地，唯一地） vegetarian⁹.