If the old saying is true that the first casualty of war is truth, so it is probably also the case that the first casualty of a recession is usually the environment.
The last time there was a serious upsurge of interest in environmentalism in Britain was in the late 1980s, when the Green Party looked briefly like it could replace the Liberal Democrats as the country’s “third force.”
It reached its apogee in the 1989 euro-elections, when the Lib Dems finished a distant fourth in terms of share of the popular vote behind the Greens.
Then came the recession of the early 1990s, and interest in green politics faded. It took years - and the prospect of runaway, irreversible man-made climate change - before it assumed the same kind of prominence on the political agenda.
Now, as Britain and the world once more face the certainty of tough economic times ahead, the environmental lobby is again struggling to make its voice heard.
Against the backdrop on the economic downturn, there was never any real doubt that Gordon Brown's Labour government would give the go-ahead to the £9bn scheme for a third runway at London's Heathrow Airport this week.
New Labour's three top priorities used to be education, education, education - but it is clear from what the Prime Minister has been saying over the past fortnight that they are now jobs, jobs, jobs.
And with unemployment set to head towards the 3m mark by the end of this year on some projections, most would say quite rightly so.
The government points out that construction work on the new runway could create 65,000 new jobs alone, in addition to the 100,000 existing jobs in the aviation industry that would be safeguarded by the project.
The additional tonnes of CO2 that will be belched into the atmosphere as a result are seen as a very secondary consideration, despite the government's pledge to reduce such emissions by 80pc by 2050.
In an effort to appease critics, Transport Secretary Geoff Hoon said airlines using the new runway would be required to use the newest, least-polluting aircraft.
Few will be convinced by that though. In reality, the Heathrow decision drives a coach-and-horses through any pretensions that Mr Brown may have had to “going green.”
But if the decision is hard to defend on environmental grounds, so too is it when seen from the perspective of regional policy.
In pure cash terms, it is another £9bn of public expenditure being channelled into the London and South-East economy on top of the £16bn already committed to the Crossrail deep tube link and heaven-knows-what for the 2012 Olympics – also hailed by Mr Brown this week as an important job-creator in the face of the downturn.
Vague talk of a more high-speed rail links between East and West and North and South to complement the runway project sounds suspiciously like political window-dressing designed to keep Northern Labour MPs quiet.
I recall that similar things were said by the Tories when the Channel Tunnel was given the go-ahead. Yet the "regional eurostars" that were supposed to link Newcastle to Paris were never used and were eventually sold-off for use elsewhere on the rail network.
Throughout the lifetime of the Blair-Brown government, it has taken the view that the prosperity of UK plc depends vitally on the economic health of London and the South-East and its ability to act as a "driver" for the economy as a whole.
Rather than seek to create a more balanced economy, it has sought to make a virtue out of the current very unbalanced one by pumping more and more resources into the capital.
However much the government may talk about regional policy, this is in fact no such thing. It is, rather, a national economic policy in which, in effect, one region is expected to deliver prosperity for all the rest.
The Heathrow decision takes this logic to a further level. If Heathrow is vital to the economy of London and the South East, which in turn is vital to the UK as a whole, then it follows that Heathrow is vital to the whole of the UK.
After 12 years in power, this particular leopard is unlikely to change its spots now, particularly as the financial centre of London and the South East is now as much in the eye of the economic storm as any other region.
Yet there was surely an opportunity here to address some of the regional economic imbalances that continue to bedevil the UK and its most outlying regions in particular.
Building a third runway with the possibility of a new North-South rail link as an afterthought was surely a reversal of what should have been the government’s priorities.
It was nice to hear the Tories talking in such terms this week, although it’s a shame they couldn’t have thought of that while they were busy creating the North-South divide in the 1980s.
The other point to be made about Heathrow is that it is on the wrong side of London. If you were building a new airport from scratch today, there is no way you would put it there.
The city's mayor, Boris Johnson, at least recognises this. His long-term dream is to move London's main airport to the Thames Estuary and retire Heathrow, enabling European flights to arrive without having to cross the city to land.
Since the outer reaches of the estuary are currently largely uninhabited, this would have had the additional merit of causing the least amount of disruption to people.
Instead, the third runway project threatens to make the communities of Sibson and Harmondsworth the modern-day equivalents of Dunwich, the lost village which fell into the sea in mediaeval times.
The political battle lines over the runway project are now clear, with Labour playing the jobs card and the Tories taking up the cause of the “little people,” threatened by noise, pollution and ultimately the loss of their homes.
But it would be naive to assume that the question of whether or not the runway will go ahead will depend entirely on the outcome of the next election.
Even if the Tories were to win, the future of the project would surely depend on what sort of state they find the economy in, and specifically what the jobless figures are looking like.
For all his supposed green credentials, it would be a brave Prime Minister Cameron who put the environment ahead of 165,000 jobs.
