In his autobiographical Confessions, St Augustine relates how hard it was for him as a young man to live up to his strenuous Christian ideals: "Give me chastity, O Lord, but not yet".

UK Ministers seem to suffer from a similar problem, only in their case it is, "Give us the courage for urgent action on climate change – but not yet."

There is pathos in this, and it could yet turn into something tragic. It is the sight of democrats struggling with a problem that is unprecedented and deeply troubling for mass democracies – one that demands upheavals for decades to come in the cause of preventing far worse disruption for future generations. There will be precious few votes for anyone willing to face up to the challenge in full.

It may be – and we citizens all have to strive to prevent it being so – that democracy is unequal to dealing with climate change mitigation and adaptation. The issues are awesomely complex and huge in scope. No-one can claim that our politicians are facing a straightforward issue and that they are being straightforwardly irresponsible or cowardly.

However, there is pathos and there is bathos. Once politicians have decided that an issue is a politically compelling, or at least unavoidable, challenge and opportunity, they can only carry conviction if they are consistent in their approach, matching deeds to words. Anything less and their statements become devalued, at worst incredible.

Three recent statements from ministers show that bathos, almost comical in its effect, is setting in.

A minister opens a think-tank seminar on the post-Bali scene by saying that climate change will transform our politics fundamentally and that it is a planetary crisis demanding urgent action, indeed a new industrial revolution. Having said this, he resolutely avoids all specific discussion of how this will require enormous changes to lifestyles, consumption and production, including in sensitive areas such as aviation.

A minister speaks at a reception for academics, businesses and NGOs working on energy. In the tones of a very tired man announcing for the umpteenth time that passengers should mind the gap when boarding the train, he declares that climate change is the biggest issue facing the planet, civilisation and the UK Government. Wearily, he intones that we all need to show "a deep sense of urgency" about climate action – something his audience could have told him.

The Chancellor presents his first Budget, trailed in advance as the greenest ever. He tells us, in a voice that makes the Speaking Clock sound like Graham Norton, that climate change is the greatest challenge we all face, and that urgent action must be taken now. And so, Mr Deputy Speaker – we will possibly legislate for compulsory charges on plastic bags.

I don't mean to be unfair. In some important ways, UK ministers have shown real leadership in recent years – for example, with the climate bill and the 2016 target for zero-carbon homes. The Budget was green-tinted at least – its measures on zero-carbon non-residential buildings, low-emission cars and, yes, plastic bags are all helpful so far as they go.

But they do not go far enough. More pointedly, they simply fail to match up in any way to the reality of climate disruption as it is diagnosed by scientists and broadcast by politicians.

If there is a civilisational risk ahead, and we agree that there is, and if time is short, and we agree that it is, then sooner rather than later a policy response that is truly "urgent" has to be put together, with unmistakeable messages to every sector that here is an unavoidable challenge, opportunity and shared endeavour.

But if we continue with bathos – announcements of impending planetary crisis, followed by vague promises, further consultations, remote targets and postponed "tough choices" – then sooner rather than later the public will conclude that the Government can't possibly mean what it says.

Writing at the height of the Cold War in the early 60s, the poet Robert Lowell spoke of how endless discussion of nuclear war had deadened people's sensibilities – "we have talked our extinction to death". Political talk about climate change is heading in the same direction.

Ian Christie is an independent consultant on sustainable development and environmental issues.