Thursday’s court decision on the Trans Mountain Pipeline has knocked the legs out from under an already flawed federal climate-change plan.

Prime Minister Justin Trudeau’s Liberal government has long promised the impossible: a coherent plan that on the one hand would combat climate change but on the other would still allow Alberta to exploit and expand its carbon-rich oilsands.

The government’s mantra has been that environmental progress need not hinder economic growth. That may be true in the long run. But in the short-run world where most of us live, there is a cost to fighting climate change.

The real problem is that the cost of not fighting climate change is arguably even greater.

For almost two years, the Trudeau government has tried to finesse the contradictions of its climate-change policies.

On the one hand, the government has talked tough, promising to impose carbon taxes on those provinces that don’t have their own.

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On the other, the proposed carbon tax itself — $10 per tonne of greenhouse gas emissions this year, rising to $50 by 2022 — is woefully inadequate to the task of weaning Canadians from their reliance on fossil fuels.

Experts I’ve talked to estimate that a carbon tax would have to start at $30 a tonne and reach at least $200 by 2030 to do any good.

The federal government has also insisted that Canada can merrily continue to mine the carbon-intensive tarsands and still meet its international greenhouse gas emission reduction obligations, which it cannot.

And it has promised to aid this carbon mining by approving a pipeline expansion that would bring bitumen from Alberta to Burnaby on British Columbia’s Pacific coast. It was this project, the Trans Mountain Pipeline, that the Federal Court of Appeal quashed Thursday.

The court’s reasons did not have to do with climate change. It ruled that the government had failed to take into account the effect of pipeline-fuelled tanker traffic on B.C. marine life.

And it ruled that Ottawa had not sufficiently consulted First Nations affected by the pipeline expansion.

But the political blowback against Ottawa’s climate-change strategy was almost immediate. Alberta Premier Rachel Notley, one of Trudeau’s few remaining provincial allies on this file, announced that she will no longer play nice.

She said that until Ottawa manages to get the Trans Mountain Pipeline on track again, Alberta will withdraw from the federal climate-change plan.

In practical terms, that doesn’t mean much. Alberta already levies a $30-per-tonne carbon tax, well above the federal minimum for 2018. Notley has no plans to change this.

Given her New Democratic government’s position in the public opinion polls, her threat to ignore Ottawa’s directive to raise the levy to $50 by 2022 may be moot.

Yet her defection has left Ottawa even more isolated. Saskatchewan and Ontario oppose carbon taxes and are taking the federal government to court over its plan. Prince Edward Island, while more polite, says it also won’t levy such a tax.

All in all, Thursday’s court ruling whacked the federal Liberal government in three ways.

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Its finding that Ottawa failed to adequately consult First Nations undercut Trudeau’s claim that his government has gone out of its way to respects Indigenous rights.

The ruling also made a mockery of the government’s decision to buy the Trans Mountain Pipeline for $4.5 billion in order to service Alberta’s tarsands.

But most of all it served as a reminder of the inadequacy of Trudeau’s climate-change plans. These plans are already under attack from the right by Conservatives such as Ontario Premier Doug Ford. They would be easier to defend if they were at all effective.

Thomas Walkom is a Toronto-based columnist covering politics. Follow him on Twitter: is a Toronto-based columnist covering politics. Follow him on Twitter: @tomwalkom

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