Going green never quite loses its capacity to surprise. Things that once seemed obvious turn out not to be. Once, we took it for granted that nuclear power was an environmental disaster story. Once, we thought windmills were a picturesque feature of a fairy-tale Middle Ages. Once, we thought British politics would never be the same because the Green Party won 15 per cent of the vote in the European Parliament elections of 1989.
And, sometimes, environmental opportunities that are staring us in the face remain unexploited. Today, we report that a nation that made its wealth on the sea, that had the most powerful navy and built an empire with it, is failing to harness its remarkable geographical advantages to lead the world in wave and tide power. The select committee of MPs that scrutinises his department has welcomed Ed Davey, the new Secretary of State for Energy and Climate Change, to his post by urging him to do more to support innovation in marine renewable energy.
Of course, we know by now that environmental sustainability requires hard choices, and that this applies to wave power too. Currently, it is more expensive than onshore wind power, which is itself more expensive than carbon-based energy, but there is more scope for the price to come down if different technologies were tested and improved. But we have to accept that putting a higher price on carbon-based energy, worldwide, is the most efficient way of cutting carbon emissions.
We know, too, that action to mitigate climate change for the sake of global ecology can conflict with the preservation of local habitats. That was one of the contradictions at the heart of the Severn tidal barrage project, which this newspaper supported but which was abandoned by the coalition Government in October 2010. If we cannot do the Severn barrage – and the idea is not completely dead yet – we should surely experiment with as many small tide- or wave-power projects as possible.
That should be the model for the new green politics: flexible, open to new ideas, willing to realise that the old certainties are getting in the way of making the right decisions. That is why we should consider returning to the expansion of nuclear power; why we should appreciate that there could be beauty in wind turbines; and why the so-called "business case" for new airports cannot always carry all before it.
Such dilemmas for government are replicated at the personal level. We might think that gardens are "green", but, as our report today suggests, there are many ways in which our attempts to commune with nature do more harm than good. Some of this is obvious, if you think about it, such as the use of water, the import of foreign plants, the use of peat and pesticides. But some of it is less so, such as the release of greenhouse gases by mowing grass and digging soil.
Then, in between the politics of personal responsibility and that of governments and intergovernmental treaties lies local government. This is where the Green Party, having elected its first MP, Caroline Lucas, two years ago, passes its next milestone this week. Brighton Council, on which it holds a majority, will be voting on its first Green Party budget. This involves making difficult compromises, because of cuts in central government funding. And the party had to abandon the idea of Meat-Free Mondays in council canteens when staff revolted. Such tensions between idealism and the politics of the locally possible are likely to dominate at the Green Party spring conference in Liverpool this week.
We hope that the Green Party continues to work through its growing pains, because for all that the main parties have pretended to take up green priorities, their commitment turned out to be fairly shallow the moment the recession hit. Britain urgently needs a green movement that understands that idealism and fixed assumptions are not enough to make progress towards a more sustainable economy. David Cameron's early promise to lead the "greenest government ever" rings increasingly hollow. His Chancellor made clear in his speech to the Tory party conference last year that he was opposed to Britain taking a lead in tackling climate change.
Let us hope that today's ragged retreat is merely the prelude to the green cause's more certain advance, older, wiser and more understanding of the hard choices that must be made. How Mr Davey will respond to George Osborne's ambition to be the slowest ship in the convoy is an important test of the new Climate Change Secretary.