UK farmers' pledge to slash their greenhouse emissions to net zero by 2040 will be "very, very difficult" to achieve if current levels of meat production are maintained, Committee on Climate Change (CCC) CEO Chris Stark has warned.

In an interview with BusinessGreen last week, Stark, who has been at the helm of the government's climate advisory body since last year, said there were no "easy answers" to agricultural emissions.

He praised the farming industry for "sensibly" setting a public goal to become net zero emission and stressed that agriculture had a crucial role to play as part of a wider net zero emission economy.

But he also warned that while it is possible to make UK farming net zero emissions "it will be a huge shift and a huge challenge".

The CCC report posits that continued shift away from red meat and dairy consumption in line with current trends among UK consumers would help to free up land for farmers to invest in carbon sequestration measures such as growing forest, restoring peatland and improving soil quality.

"We know that younger generations are eating less meat… A fall in red meat and dairy of about 20 per cent in consumption doesn't seem to me to be overall a difficult thing to project and model, and that would free up a lot of land to do CO2 removal," Stark explained. "And again, that's agricultural land. So that sector - I think this is a great opportunity for them to be part of the overall story on emissions reduction."

The National Farmers' Union (NFU) has set an ambition to reach net zero emissions from the sector by 2040. However, it also asserts that it does not want to reduce meat production, and that it will export its produce abroad if a consumer shift towards plant-based diets continues in the UK.

UK agriculture and land use are together seen as among the most challenging to decarbonise, and last week the CCC said a 20 per cent reduction in beef, lamb, and dairy consumption would be a key component of the UK as a whole reaching net zero emissions by 2050.

It also suggested cutting beef, lamb and dairy consumption could free up land for rewilding, planting more trees, restoring peatland and cultivating biomass energy crops, all of which the Committee believes are crucial to ending the UK's contribution to global warming by the middle of the century.

Meanwhile, a separate study last week estimated that if everyone swapped one red meat meal for a plant-based alternative every week it could slash UK emissions by 50 million tonnes, which is roughly 8.4 per cent of total UK greenhouse gases.

Stark said he was "pleased" the NFU had set a goal to reach net zero by 2040, but hinted that doing so while maintaining current production levels would be tough. "It's certainly possible to achieve it, but it will be a huge shift and a huge challenge," he said. "That industry, it seems to me, is approaching it sensibly by declaring they are willing to have that kind of ambition."

But NFU deputy president Guy Smith - while welcoming the CCC's analysis and reasserting its ambition to hit net zero by 2040 - last week dismissed suggestions farmers should curb production in order to help the UK reach its climate targets.

In response to the CCC's analysis, he said the UK "will not halt climate change by curbing British production and exporting it to countries which may not have the same environmental conscience, or ambition to reduce their climate impact".

He suggested the UK should instead "farm smarter, focusing on improving productivity, encouraging carbon capture and boosting our production of renewable energy" to help mitigate the industry's climate impact.

He also argued most UK farmland is well suited for livestock production. "In Britain, 65 per cent of our farmland is best suited to grazing animals, so our ambition is that the climate impact of UK grazing is amongst the lowest in the world," Smith said, stressing that beef production in western Europe is 2.5 times more carbon efficient than the global average.

"British farmers have an important role to play in tackling climate change and our members are committed to this challenge, alongside fulfilling their responsibility to the public in providing high quality, sustainable and affordable food," he added.

His comments echoed those of NFU president Minette Batters, who last month rejected suggestions livestock production would need to fall, arguing the sector needed strong policy certainty and support from the government in order to decarbonise.

"What we are against is the idea that we should tailor production to human diets," she said. "I think diets do need to evolve, but there is no need for farmers to be changing their production. In fact what we're not consuming here we should be prepared to export."

Yet the CCC's analysis, which recommends a fifth of the UK's current agricultural land should shift towards afforestation, energy crops and peatland restoration, appears to suggest the farming sector may face some trade-offs as it decarbonises.

Nevertheless, Stark said the opportunity afforded by Brexit to overhaul the EU farming subsidy regime to incentivise more climate-friendly land management practices made him "quite optimistic actually that we can achieve a lot more than we have in the past for agriculture".

Eradicating greenhouse gases altogether from livestock in the UK would be difficult, Stark conceded, but through carbon sequestration and other techniques it would be possible to "net-off emissions", arguing the CCC's modelling for dietary shifts "isn't actually that extreme at all".

"I would love to see farmers in the UK and the agriculture sector more generally move into the world where they are part of the answer there," he told BusinessGreen. "Carbon sequestration, growing forest, restoring peatland - these are absolutely essential in all of the scenarios we have in this report. That will not be successful unless it is the agriculture sector itself that delivers them."