Almost unnoticed, something momentous has happened. It could even turn out to be the most hopeful development for both the economy and the environment in a generation, and set Britain on track for a new industrial revolution, powered by clean energy.

Over the past two weeks the Prime Minister, his predecessor and the Leader of the Opposition have all insisted that any future growth must be green – as have world business leaders. Indeed Gordon Brown and David Cameron have gone further, making it clear that otherwise there may well be no growth at all.

This is not what is supposed to happen at this ominous stage of the economic cycle. For months the commentariat have been telling us that green concerns will inevitably slip down the agenda as times get tough. But there has been an unexpected, if overdue, paradigm shift: the environment and the economy are now recognised to be interdependent.

David Cameron was first up. Two weeks ago he said: "For the sake of our future prosperity ... we must go green." Four days later, the chief executives of 100 big companies ranging from Dupont to Deutsche Bank called for tough measures to slash carbon dioxide emissions "to drive forward the next chapter of technological innovation" and kickstart "a green industrial revolution". On Friday, Tony Blair resurfaced in Tokyo to call for "a new and green economy". But, for once, Gordon Brown upstaged the old ham, and showed himself more in tune with the zeitgeist.

Brown, in a surprisingly stonking speech, said that "the global low carbon economy will be a key driver of our economic prosperity". It would bring a "fourth technological transformation" to follow those historically wrought by the "steam engine, the internal combustion engine and the microprocessors".

In perhaps the boldest move of his premiership – and one of the few in which he has actually delivered the change he promised on entering No 10 – he launched a detailed, ambitious strategy for a 10-fold expansion of renewable energy in just 12 years.

The initiative springs from a day in October when a hand-wringing Business minister John Hutton – no natural fan of renewables – complained about having to meet an EU target to get 15 per cent of our energy from them by 2020. With unwonted decisiveness, Brown told him that the target must be met even though, as Downing Street admits, it is "at the limits of achievability". And he followed through. Hutton's notoriously recalcitrant department was reorganised and able officials brought in to manage the strategy. Sceptical departments, like Defence and Transport, were sat upon, and the whole Government brought behind the change.

Most media coverage of the new strategy concentrated on possible increases in fuel bills. But Downing Street has largely shrugged it off on a rare high at having for once initiated something new and important. And who knows? If it happens, and starts a trend of creating real change, it might breathe new life not just into the economy and the environment, but into the increasingly moribund Brown premiership itself.