Scottish Greens co-leader Patrick Harvie has said he “honestly does not know” if his party will stay in government with the SNP.

Green members are to vote on whether to end a power-sharing deal with the SNP after it scrapped key climate change targets.

Mr Harvie told BBC Scotland it would be his preference to remain in government where the party could achieve more.

The Greens are to hold an extraordinary general meeting to decide the issue.

The BBC understands it is expected to hear a single motion on “whether the party continues to co-operate with the Scottish government or not”.

First Minister Humza Yousaf has said he values the power-sharing deal – known as the Bute House agreement, – and does not expect it to be scrapped.

He reiterated his support for the agreement before a pro-independence march in Glasgow on Saturday where he was joined by Greens MSP Ross Greer.

When asked if he expected to soon be leading a minority government, he said: “I don’t think that will be the case but it’s clearly a discussion that the Greens will have to have.”

Mr Harvie told BBC Scotland’s The Sunday Show he shared the anger of his party members over the fact that reducing greenhouse gas emissions by 75% by 2030 – which has been scrapped – was unachievable. The long-term target of achieving net zero by 2045 remains.

“It’s been clear for a long time now that Scotland is not on track to meet that target,” Mr Harvie told the programme.

“The truth is that while, for a long time, some people have been happy to describe Scotland as a world leader, or have self-congratulatory speeches about setting targets, we are years behind where we should be on taking the actions to reduce emissions.”

He said there had been times when the Greens had been arguing for transformational changes and other parties that had voted for the targets voted against those changes.

“This is a moment that’s critical for the future of climate policy in Scotland and critical to the future of our party,” he said.

“Over the next few weeks we have probably the most important decision to make that we’ve ever had to make about the future of our party.

“My worry is that if we walked away at this point, we would decelerate climate action.”

Mr Harvie said he did not know whether the Greens would remain in government – where he and fellow Greens co-leader Lorna Slater have cabinet posts.

“The first thing I hope is that every party member engages with this and that every party member goes into this trying to listen to each other’s perspective and to think very deeply about the most important decision we’ve ever made,” he said.

“My instinct is that we will achieve far more by staying in government, not only in terms of good climate policy and a whole host of other policies, but I don’t just want our members to think ‘yea, grudgingly on balance we’ll probably do more good by staying’.

“I want them to feel enthusiastic and reassured that not only the Greens and the Scottish government but Scotland is on the right track here.

“We clearly have more to do to persuade them of that.”

When asked if his leadership was on the line after 16 years, he said: “That’s the least important question. This is about what’s the future of climate policy and the greens have a decision to make that is critical to the future of our party.”

Scottish Green councillor for Glasgow, Anthony Carroll, told The Sunday Show he had “never seen discontent at the level that we have in the party in terms of membership”.

He added that he was “leaning towards voting to leave the agreement”.

Mr Harvie was also asked about the Cass Review in England in which paediatrician Dr Hilary Cass said children had been let down by a lack of research and “remarkably weak” evidence on medical interventions in gender care.

As a result, Scotland’s only specialist gender clinic, the Sandyford, paused prescribing puberty blockers to children.

Green MSP Ross Greer has described the report as a “transphobic, conservative document”.

When asked on The Sunday Show if he accepted that the Cass report was a valid scientific document, Mr Harvie said: “I’ve seen far too many criticisms of it to be able to say that.”

“The decision that was made last week was not a government decision. It was made by individual clinicians.”

SNP MSP Michelle Thomson said Mr Harvie’s response was “unbelievable”.

“It’s, in effect, a form of science denialism,” she said. “That’s heading towards the world of Trump.

“Nobody who had read and understood the report could not agree it was entirely evidence-based and scientific from someone who is extremely well regarded as a leading academic and paediatrician in their field.

“The Greens need to decide that within their role in the Scottish government they either respond to evidence – even if they don’t agree or are disappointed or dismayed by its findings – or they don’t. If they don’t, I cant see how it won’t call into question the Bute House agreement.

“I don’t think that we should continue in partnership with the Greens.”