SNP ministers have been threatened with court action for failing to produce a full climate impact assessment for a key investment plan despite admitting a failure to do so has breached its own legislation.

The Environmental Rights Centre for Scotland (ERCS) and the Good Law Project have warned that the Scottish Government could be taken to court if it fails to bring forward the full climate impact assessment to its £26 billion infrastructure investment plan, which is key to Scotland achieving its legal 2045 net zo target.

Last month, the Scottish Government accepted its failure to produce the assessment was a breach of the Climate Change (Scotland) Act 2009.

In a letter, the Scottish Government pledged to begin “urgent work” after admitting they have breached their own legal climate change legislation.

But campaigners have claimed that SNP ministers are so far refusing to provide a transparent climate assessment to back up their pledge to do so.

The groups have warned that without quantifying emissions or showing their calculations, it is impossible to verify whether or not the infrastructure investment plan is fully compatible with emissions reduction targets.

The Scottish Government has committed to share the assessment with the campaigners “as soon as possible and before the end of the calendar year”, adding that publication of the document is “anticipated in early course thereafter”.

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But the campaigners disagree with the Scottish Government on what will need to be published to meet legal requirements, opening up the prospect of court action against SNP ministers.

In a letter sent to the campaigners, government officials have insisted that “the Scottish Government is absolutely committed to tackling the twin challenges of climate change and biodiversity loss” and “intend to publish an update of the IIP (infrastructure investment plan) pipeline alongside the 2024-2025 Budget”.

In response to the Scottish Government, a letter from lawyers representing the campaigners has warned that the proposed remedy from ministers “would be restricted to identifying the current emissions target and indicating whether the target is more or less likely to be met” due to the investment plan.

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It adds: “That is neither an assessment nor a publication of the extent of the contribution of the emissions to the target, and leaves the public with no way of verifying how the assessment has been carried out and, crucially, whether it has been carried out properly.

“That would be to undermine and thwart the clear intention of the legislation.”

The correspondence adds that “cooperation can avoid altogether the need to become involved in court proceedings”.

But it warns that “if there remains any material disagreement”, the campaigners “would have to reconsider their position – there would be no point waiting for a report that was doomed to fail the statutory requirements”.

Good Law Project legal director, Emma Dearnaley, said: "Scottish ministers need to show us how their flagship plan will meet vital climate targets.

“They’ve said they are committed to reducing emissions but words are not enough - we need to know that their plans will actually deliver so that crucial targets to reach net zero can be met.

“It is heartening that they’ve accepted they’re in breach of their legal duties and promised to remedy the situation. Now they must make good their shortfall - and we’ll be standing by and ready to take legal action if needed.”

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Dr Shivali Fifield, chief officer at ERCS, said: “Decisions made about infrastructure today will shape Scotland for decades to come, and it is in the national interest to ensure full transparency so that we can scrutinise the impacts.

“With £26 billion of public funds at stake, it is essential that plans align with net zero commitments and meet the standards expected by the Scottish people.

“We are glad the Scottish Government has promised to fix the legal breach we have identified, but there is too much dithering and their actions still fall short of what is required.

“The Government must clearly demonstrate their emissions calculations and how these will meet the targets set out in their Climate Change Plan.”

A Scottish Government spokesperson said: “We are working at pace to publish an assessment, engaging with Environmental Standards Scotland.”