I am less interested in the potency of these threats than in what I am expected to do about them. The implication with fish is that we must stop eating them at once in the hope of resuming their consumption later, or accept that they will go the way of mammoths and sabre-tooth tigers.

To bring this about I must rely on the government. Yet Ben Bradshaw, the fisheries minister, said on Friday that his responsibility was “to the livelihood of Britain’s fishing industry”. This is like confronting climate change by subsidising the oil industry and confronting terror by sponsoring the Taliban.

Environmental news is fashioned to scare people witless. I recall reporting a conference of “top scientists” in the 1970s from which I extracted a spine-chilling threat of a new ice age. Particulates in the atmosphere were blotting out the sun. The Earth’s surface was cooling, tundra advancing and ever more pollution going aloft in the effort to keep us warm, thus accelerating “global dimming”. We were all going to freeze.

The latest environmental blast runs counter to this but the millenarian fervour is the same. If climate change and marine catastrophe are, as Blair claims, the biggest threat to mankind, surely the obligation to confront it is his. The coal burning, petrol consuming and fishing industries must be treated as enemies not just of the nation but of the planet. Yet Blair treats the global warmers with nine indulgent years of reduced petrol taxes and subsidised transport infrastructure. He worships at the altar of hypermobility.

By using the metaphor of an ecological “time bomb”, scientists may engage Blair’s passing attention but they risk longer-term ridicule and neglect. There is no point in walking the nation to the top of a mountain and promising hell fire and damnation if the only proof is a sunny day and a retreating glacier. While the threat of terrorism may be grossly overstated, it is at least recognisable. Climate change is a stew of statistics, trends, equations, qualifications, distant dates and vast sums of money. A stage army of ghouls, mini-Einsteins and e-babies traipse the conference circuit “hyping the issue” until it becomes a long, shrill scream of doom.

This, of course, is not the end of the matter. Through all the accumulated noise, it now takes a perverse unreason to deny that something dramatic is occurring in the Earth’s temperature and that this has to do with human behaviour. Wise counsel is that this can and should be countered, but how? The admonition that we each change our lives to “save the planet” (or, rather, our lifestyle on it) is on a par with ancient monks advocating flagellation as the path to salvation. Personal choice and market forces left to their own devices will plainly not do the trick. It is therefore equally perverse to eschew the precautionary principle. Will the end and you must will the means, and that involves political action.

In 1960 Herman Khan, the nuclear scientist, conceived the Doomsday Machine. This was designed to respond to a nuclear attack by triggering a global holocaust that no human intervention could stop, thus deterring an enemy by assuring “mutual assured destruction”.

Young people today find it hard to conceive of the threats under which their parents grew up. But that terror did drive the nuclear de-escalation that accompanied the end of the cold war. The wilder fringes of the anti-nuclear movement permeated the arms control process. A similar concern for the ozone layer spurred collective action to eliminate CFCs in the 1990s. The same must apply to climate change. The fringe must move into the mainstream and win the argument through reason.

There is evidence that this is happening. Last week the economists rode to the rescue of the scientists in Sir Nicholas Stern’s review of climate change. It took science at its word and put forward measures to correct what Stern drily called “the greatest market failure the world has ever seen”. That failure is to the global equilibrium which James Lovelock called the “Gaia thesis”. This portrayed the Earth as a complex self-regulating mechanism of organisms constantly adjusting “so as always to be as favourable as possible to contemporary life”. This adjustment was nature’s equivalent of Adam Smith’s invisible hand and was a comforting riposte to ecological hysterics. Lovelock, too, has now decided that the equilibrium has broken down, leading Gaia helter-skelter towards disaster.

Again adopting the precautionary principle, Stern regards this destination as avoidable. He accepts the evidence of change: shrinking glaciers, the loss of reflectivity (the albedo effect), methane leakage and soaring carbon emissions. But rather than crying panic and heading for the hills, he says that governments should tackle the prime cause — the inability of the world’s economy to impose on individuals or countries the external costs of their actions, their burning of carbon fuels especially in pursuit of mobility. Even a free market economist requires governments to correct market imperfections.

Debate is moving forward. The British government’s soft-heartedness towards the transport and fuel lobbies as proxies for middle-class drivers and flyers appears to be weakening. It accepts, as do the Conservatives, that taxes should be directed at curbing carbon emissions, coupled with carbon trading, road pricing and investment in conservation and solar and nuclear power. As against the costs (and risks) of nuclear energy, the global disaster presaged by continued burning of carbons is now beyond sensible argument.

Carbon emissions are easy to subject to price control since most are taxed or regulated already. The chief hurdle has been the timidity of governments, and that now seems susceptible to shame.

Stern’s conclusion is that life on Earth can be stabilised over the next two decades without extreme measures and without abandoning growth. Salvation lies within the grasp of the chancellor of the exchequer. But this applies only if taxing carbon rich energy consumption leads to a genuine change in human behaviour and not just a shift between cars, buses, trains and planes, where the impact could be marginal.

We are nowhere near this point. Last week politicians lined up to insist that carbon taxes should not curb the mobility of the poor. Yet it is the poor who, by growing richer and using more fuel, have precipitated this crisis. It is the availability of cheap petrol and aviation fuel that has enabled the Chinese and Indians as well as the Americans and Europeans to deluge the atmosphere with filth. If this policy is to mean anything there is no alternative, in the absence of fuel cells, to driving these people back into their homes and villages or onto their bicycles.

Those of us who greeted this new apocalypse with scepticism cannot sensibly ignore it. But I wonder if those with their heads in the sand are not many of the same environmentalists who raised the hue and cry in the first place. If life on Earth really faces a moment of danger, it requires joined-up thought. It means urgent investment in nuclear power, a global curb on mobility, holidays at home, wrapping up warm, living in denser cities and a halt to rural colonisation. It means farm protectionism. It means keeping open local schools and hospitals, leaving roads to congest and curbing airports. Planning must become carbon obsessed.

Income taxes will not achieve this, only taxes targeted against high carbon expenditures, above all on movement. Travelling, especially flying, must be regarded as a luxury whose cost to the planet must be transferred to the individual. This concept of “re-localising” human settlement is still in the wilder realms of idealism. But like other fringe ideas it will have to move into the mainstream. There is no point in denying what this means.

Mobility will again become the privilege of the rich.

simon.jenkins@sunday-times.co.uk

Times Recommends

• Chelsea Flower Show has lost the plot
• The age of personal vitriolic abuse
• Obama: the new Great Redeemer