Some tout wind turbines or nuclear power. Others insist on micropower or biodiesel. Everyone has a preferred solution to global warming. But few seem to have realised that all their efforts will come to nothing if an increasing number of jet aircraft continue to take to Britain's crowded skies.
Aviation is the fastest-growing source of greenhouse-gas emissions, already accounting for eight million tonnes of carbon dioxide each year - more than 10 per cent of the UK total. The sheer rate of growth is staggering: at 12 per cent per year, aviation is growing faster here than even in the boom economy of China.
This will be an environmental catastrophe, yet instead of trying to rein in the destructive surge in flying, government ministers are assiduously promoting its growth. The Labour government plans to bulldoze communities across the country for new runways and access roads, pushing the Kyoto goals out of reach for ever and giving a terrible boost to global warming.
A recent letter from Tony Blair to the campaign coalition Stop Climate Chaos shows just what a master of doublethink he has become. The government's initiatives on global warming will "reduce carbon emissions by over seven million tonnes by 2010", he crowed. Even if this were true (which is doubtful), the growth in the aviation sector would more than wipe out these gains by the end of the decade. Blair claims to think that "climate change is, without doubt, the major long-term threat facing our planet", yet the actions of his government make him just as culpable for the coming crisis as more familiar demons such as ExxonMobil or George W Bush.
It has often been said that unlimited growth is the ideology of the cancer cell. If so, then aviation's tumours are metastasising all over Britain. No major city today is complete without its own local airport, offering cheap flights to an ever-increasing list of domestic and international destinations. Heathrow is already making plans for a sixth terminal - even while the fifth is still a gigantic building site - and a third runway. Twelve other airports, including Aberdeen, Edinburgh, Southampton, Norwich and Swansea, are planning large-scale expansions. Six, including Stansted, Edinburgh, Glasgow and possibly Gatwick, may almost double in size with new runways.
As an unavoidable consequence, aviation emissions will double by 2020 and quadruple by 2050, a prospect that makes a mockery of all other national efforts to combat global warming. According to a recent report by the Tyndall Centre for Climate Change Research, even if we were to shut down the rest of the economy in order to save on greenhouse-gas emissions, aviation alone would bust the sustainable emissions budget by the middle of the century. Without heating, lights, cars, factories or any of the other sources of pollution, the growth in flying alone will propel us into a future of melting ice caps, spreading deserts, rising sea levels, vanishing farmland and collapsing ecosystems.
The stance of our presumed prime minister-in-waiting, Gordon Brown, is if anything even worse than Blair's - although at least Brown doesn't bother trying to make us believe he knows or cares much about global warming. His Budget tossed a few crumbs in the direction of the environmental movement (pre-sumably with one eye on David Cameron's shiny new micro wind turbine) but, like Bush, Brown insists that nothing should get in the way of economic growth - not even the planet.
A stark example of Brown's poverty of imagination emerged in the Budget: householders, he said, would get support to fluff up their loft insulation, supposedly saving 35,000 tonnes of CO² per year. Big deal: this is the same amount that a single jumbo jet pumps out in the course of 25 return trips to Miami. And Brown is the biggest aviation enthusiast of all.
He's too canny to draw attention to this openly, of course. You need to read the small print - in this case a couple of paragraphs buried right at the end of chapter three of the pre-Budget report, under a section entitled "Meeting the Productivity Challenge". "The government is committed to meeting the demand for additional runway capacity in the south-east," the report says, in the name of which "a second runway at Stansted should be delivered as soon as possible".
The document goes on to commit the government to sup- porting Stansted expansion with a "package" of "surface access improvements" - code for new roads and motorways, all of which will be built at public expense, to funnel ever more traffic into the expanding airport.
Clear-sighted MPs on the Commons environmental audit committee have rightly lambasted the government's approach as the same old model of "predict and provide", which brought chaos and endless traffic growth to British roads. Ministers "predict" an increase in aviation passenger journeys from 180 million passengers per year at present to 476 million by 2030. This, the MPs point out, is the equivalent of another Heathrow every five years.
A government truly committed to achieving climate-change goals would rein in demand in the interests of sustainability and future generations. Instead, as the committee charges, "the Department for Transport has forecast future demand and then provided the framework to meet practically all of it. It is actively promoting growth on the scale envisaged", rather than being a neutral arbiter.
Just as building new roads created more traffic to fill them, building new runways and airports will encourage more people to adopt lifestyles that include lots of flying, such as second homes in Malaga, weekend shopping breaks in Prague, or family ties in Sydney.
Just look at where the big money is being spent. The private sector's price tag for Stansted's proposed runway is £2.7bn, somewhere between ten and a hundred times the amount the government puts into its entire climate-change programme, windmills, loft insulation schemes and cycle lanes included.
The government's one response to these concerns has been to seek the inclusion of aviation in the European Emissions Trading Scheme. The vague idea seems to be that airlines would buy carbon credits on the open market to cover their emissions, necessitating equivalent cuts in other polluting sectors of the economy. What happens when there aren't enough credits to go round? The answer seems obvious: given that the rest of the European economy won't want to roll over and shut down, the airlines will just bust the budget.
But maybe there's a technofix, where the white knight of technology miraculously rides to the rescue? The industry claims that its jet engines are becoming steadily more efficient, but the truth is that any likely emissions reductions will be quickly swamped by the increase in flights.
A bolder approach would be to launch aircraft which burn either hydrogen or biofuels. Alas, no experts believe such a thing is even on the radar for decades yet. Hydrogen is too bulky to work as a fuel, and in any case its combustion output of water, when injected high in the stratosphere, would contribute to global warming rather than reducing it. As for biofuels, they don't have the energy density of kerosene (the standard fossil jet fuel), and the business of producing them in large quantities is already endangering food security and boosting deforestation across the tropics. There is simply no possibility that they could be produced in the volume needed to slake the thirst of jet aircraft in the long term.
Another solution we are offered is carbon offsets, a sort of voluntary "tax" on airline tickets which goes to plant trees or fund renewable energy projects in the developing world. One of the companies offering offsets is Climate Care, which uses cash wrung from guilty frequent flyers to fund small-scale projects such as biogas digesters in India or low-energy school lighting in Kazakhstan. The projects undoubtedly bring benefits to their recipient communities, but it is far from clear whether or not they really neutralise the hugely damaging atmospheric impact of flying. Their psychological impact is also questionable: are they simply salving the consciences of people who might otherwise scale back their flights?
In this dreadful, dark picture there is one glimmer of hope. A no-flying movement is beginning to take shape, with many people voluntarily committing not to fly at all for non-essential trips. It is already a sufficiently large market to be taken seriously by the newspaper travel supplements, which are starting to provide information on train or shipping alternatives. And there are benefits. Travel to the Alps by train and you get a real sense of geography, of evolving culture and changing climatic zones. Arrive by air and all you see is identikit airport terminals and thousands of other culture-shocked, aggravated travellers. Slow travel, like slow food, is about clawing back quality of life.
Perhaps it is to this incipient movement that Gordon Brown and Tony Blair should look if they want to avoid going down in history - as they surely will on present form - as villains or fools who chose the wrong side of the struggle against global warming. No, Mr Brown, Stansted's second runway should not be "delivered as soon as possible". No, Mr Blair, Heathrow should not be given a sixth terminal and a third runway.
As the writer George Monbiot has pointed out, the farmland around Heathrow village once grew some of the best apples in England, and the cargo planes bringing out-of-season strawberries from California are touching down on grubbed-out orchards and market gardens. If we begin to rein in aviation, perhaps Britain can flower once again.
Here's a positive vision for the future: rather than opening new runways, the government should be closing them down.