The UK government’s official advisor on climate change is to recommend the country reaches net zero on fossil fuel emissions by 2050, but will say Wales should not have to meet the full target due to its sheep farming industry.

The Climate Change Committee proposals would mean the UK would have the toughest legally binding targets of any leading economy.

The report, which will be released on 2 May, will suggest Scotland can reach net zero greenhouse gas emissions by 2045, but says by 2050, Wales should target reductions of 95 per cent, according to Bloomberg who said they had spoken to sources familiar with the plans.

Last year the CCC said the number of sheep and cattle in the UK should be reduced by between a fifth and a half as they are the species contributing the most emissions.

The advice said that a 20-50 per cent reduction in beef and lamb pasture could release 3-7 million hectares of grassland from the current 12 million hectares in the UK.

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The grassland could then be repurposed to grow forests and biofuels to help soak up CO2.

The advice was not welcomed by farmers, with the NFU saying at the time it did not agree with reducing livestock numbers.

There are more than 10 million sheep in Wales, accounting for almost a third of all sheep in the UK.

However, the NFU recently announced its own 2040 UK net zero emissions target for agriculture.

In a statement it did not mention the need to cut livestock numbers, but Minette Batters, the union’s president said: “Last year’s extreme weather was a stark reminder of the challenges farmers face in maintaining yields and feeding livestock on the frontline of climate change. But not only can agriculture be part of the solution, we can also be a world leader in climate-friendly production.”

She added: “Technology and the bioeconomy present huge opportunities and that is why earlier this year I unveiled an ambitious aspiration for net zero agriculture in the UK by 2040. In order to achieve that, we will need to see the government work with farmers and growers on the new technology and innovation needed to reach this goal.”

The UK’s current goal is to emit 80 per cent less by 2050 than the country did in 1990 – a target the country is already not on track to hit.

The CCC is also understood to be advising the economic outlay to hit net zero will be 1-2 per cent of 2050 gross domestic product, The Financial Times reports.

This is the same percentage estimated a decade ago when the committee first recommended emission reductions of 80 per cent.

Ahead of the report’s release Lord Adair Turner, chair of the Energy Transitions Commission, said the falling cost of renewable energy technology would help the UK’s transition to a low carbon economy.

“Two things have changed since we passed the Climate Change Act in 2008,” he said.

“One is that it is absolutely clear that the climate is changing and that it is man-made; there is now no legitimate debate about that. The second thing is that the costs of decarbonising have come down, and we have seen falls in the costs of wind, solar and batteries much bigger and faster than anyone expected – 65 per cent for wind, 80 per cent for solar and batteries,” he said.

The release of the report comes during a surge in awareness of the impacts of climate change.

Last week the teenager who kickstarted the school strikes which led to protests round the world, Greta Thunberg, accused the UK of “very creative carbon accounting”.

She pointed out the government’s current claims that greenhouse gas emissions have fallen by 42 per cent since 1990 was only accurate because it excludes emissions from international aviation, shipping and imports, and said the true figure was closer to a 10 per cent reduction.

Additional pressure from mass protests including occupations in London by the group Extinction Rebellion have also helped move the issue up the political agenda and helped build cross-party support for tackling pollution.

Their actions have won the support of BBC presenter and naturalist Sir David Attenborough who dismissed critics of their tactics as cynics.

Business leaders have also voiced strong support for tackling the problem, but said the government must act to lay a framework which businesses can adhere to.

Matthew Fell, chief UK policy director at the Confederation of British Industry (CBI) said: “Business is up for the net zero challenge – and many companies have made their own pledges for a net zero target. This is partly driven by public demand for action on climate change. But there are also economic opportunities ahead, and with other countries moving in the same direction there’s clearly a massive opportunity for exports, making net zero an essential part of ‘Brand Britain’ as we move into a new international era.

“But it won’t happen on its own – and in terms of what business needs from government, I would sum it up as ‘certainty, certainty, certainty’. Firstly, signing up to net zero will provide certainty about the destination. Secondly, we need certainty about the policy framework that’s going to get us there – an end to the chopping and changing that we’ve seen in recent years. And finally, political certainty so we don’t have big changes after every general election. It’s heartening therefore to see the strong cross-party consensus on net zero.

Jeremy Corbyn’s Labour Party will force a vote in parliament on Wednesday to declare a national environmental and climate change emergency.