Soaring oil prices and a deteriorating financial position is a nightmare for cabinet ministers. However, it should be good news for the Green party, which can argue that this as an opportunity finally to force its economic policies centre stage.

The Greens insist that combating climate change is the party's raison d'être for participation in the Fianna Fail-led coalition.

Ireland's excessive carbon production from use of fossil fuel, the party claims, is a big contributor to global climate change and the dire consequences that face the planet. That's why a main Green objective is the introduction of a carbon tax, a form of punishment for those engaged in economic and social activity using fossil fuel-derived energy.

There is no arguing with the Greens' position that we depend excessively in this country on fossil fuels. Consequently, consumer lifestyles and the profitability of businesses will certainly suffer now their price has rocketed. It is also true that we are out of line with the rest of Europe when it comes to our dependence on these pollutants. (Awkwardly for the Greens, this is partly because they are opposed to carbon-emission-free nuclear fuel.)

The Green plan for weaning us off fossil fuels is painful. Pushing up the price of petrol, diesel, home heating oil, electricity and gas by slapping a carbon tax on top of excise duties and Vat would be deeply unfair to most people, particularly as prices have increased so much already in the past year.

Those on low and moderate incomes would be most badly affected. Also in the frame would be those homeowners who bought overpriced and poorly insulated houses and apartments during the last decade, usually in public transport-free zones based long distances from where they work. More taxes on these commuters could prove catastrophic as mortgage payments increase and pay rises are put on hold.

Businesses don't need the additional costs of carbon taxes either as their profit margins contract. Our exporters are in trouble as the euro maintains its strength against the dollar and sterling and with transport costs hitting new highs, companies are looking for reductions in Vat and excise duties on fuel - not further taxes. But these hard-luck stories are falling on deaf Green ears.

Last December Bertie Ahern indulged John Gormley by allowing the environment minister to deliver a “pilot carbon budget” just a day after the then finance minister Brian Cowen delivered the real thing. Gormley boasted of putting climate change “at the heart of government decision-making”, placing it on a par with managing the economy and lecturing the nation on the need to put a price on carbon.

In today's changed environment I seriously doubt that either Cowen or Brian Lenihan, his finance minister, want to be bothered with this stuff as they struggle with pressing financial problems. The Greens, of course, argue that many of their measures are “revenue neutral”, doing no more than redistributing tax on the “polluter pays” principle. But such measures are rarely revenue neutral and the punishment for those who have no choice but to consume may be politically unacceptable.

In addition, Cowen's interest in Green issues is suspect. Before last year's general election he made it clear he was sceptical about a country the size of Ireland influencing climate change. And it was Ahern who insisted that the Greens be included in government.

It is also significant that the Commission on Taxation, which was told to produce an interim report by November, has not yet been charged with the task of debating carbon taxes. It is obvious that Fianna Fail does not want to take a risk by raising or introducing new taxes ahead of next year's elections.

But even though there are numerous reasons why the Greens could find their big idea stymied, there may yet be a twist in this tale. What if Lenihan fails to make the required savings in public spending and is faced with the prospect of raising taxes in December? Might he and Cowen not be tempted to raise the extra revenue under the cover of “the necessity” to introduce carbon taxes?

Don't rule it out. The government is spending ¤15m on an advertising campaign warning that climate change is the greatest crisis facing the Irish people in the 21st century. This softening-up exercise is already showing results. Recent market research suggests massive public approval for carbon taxes and other measures to save the planet.

Whether this support survives the drop in living standards is another matter entirely. The Greens are in danger of overdoing the apocalyptic stuff, quoting science with all the fervour of religious fundamentalists.

Irish people had enough of that from priests in the past without taking it from Green druids, especially if they start extracting more cash from our pockets. Trendy middle-class concern for environmental issues didn't translate into votes in last year's election and the failure of the Greens to make their much anticipated breakthrough by winning more seats was masked by their inclusion in government.

Tokenism won't go down well either. Last week Gormley confirmed the introduction of a carbon offset programme that greatly increases the cost to the state of foreign travel. Every time a minister or public servant jets off on state business a payment will be made to an international fund as compensation for the carbon footprint. The cost could be ¤400,000 a year, according to some estimates.

It may seem like small stuff, but such things cause massive irritation when cutbacks in essential services are on the way.

Voters are also questioning some of the Greens' spending plans. Over ¤220m is to be invested in research and development of new energy sources over the next five years but the payback is highly uncertain.

Meanwhile, grants for insulation and already proven small-scale domestic alternative energy provision have been slashed. The Greens are boasting improvements in building standards, but so what? Nobody's building houses any more.

Gormley and his colleagues need to put some big political scores on the board in the next two years if they are to justify their presence in a government that is likely to become increasingly unpopular. Instead, the debits are mounting. They were caught on the wrong side of the Lisbon treaty referendum, Gormley has been unable to stop the Ringsend incinerator in his own constituency and when toxic waste was found in Haulbowline in Dan Boyle's heartland, the Green leader slagged off the contractor who dug it up. If Gormley was in opposition he'd be demanding money to clean up the toxic mess. Now he's in cabinet he knows it's not there.

The Greens could use their place in government to push for investment in public transport instead of new roads, to encourage the switch to new energy generation and to promote what are called, euphemistically, “more sustainable lifestyles”, but all this costs money and there isn't too much of it about.

That's why the introduction of a carbon tax remains their ace in the hole. Fianna Fail hasn't bought into the long-term vision, but if the public finances continue to worsen, don't bet against Cowen using the Greens as a shield to raise badly needed revenue.

matt.cooper@sunday-times.ie

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