The popularity of the Green Party, and environmentalism more generally, is always a bad sign for the left. This is not because support for the Greens is inversely correlated to the electoral popularity of centre-left parties like Labour, though there is an element of ebb and flow between them, but because it remains a fundamentally conservative project, despite the delusions of self-proclaimed progressives, and thus a pointer to the temper of the times. The addition of 2,000 new members to the Scottish Green Party post-referendum does not presage a radical tidal wave at the 2015 general election, any more than the yes campaign revealed a social democratic nation north of the border. Support for the Greens tends to rise during periods of anxiety, such as the 1980s (recession, nuclear war) and now (recession, climate change), but that support remains centred on small capitalists and the professional middle classes, hence their greater threat to the LibDems (who are now facing a perfect storm in 2015).
The reactionary roots of environmental philosophy are well-known: the valorisation of the indigenous, of stewardship and sustainability (all of which privilege incumbency); the preservation of pre-industrial custom (with its roots in the ethnographic divide and rule of imperialism); the belief in a natural order and harmony that we challenge at our peril (Gaia and similar mysticism); and the tendency to respect most animals more than some people. The tap root of this ideology is the idea of man - historically Western, Christian man - as the image of god and thus god-like in his power. While man is undoubtedly a menace to himself and all other species, and anthropogenic climate change is real, his impact on the planet is akin to fleas on a dog. Man is not "the destroyer of worlds" (Oppenheimer's quote in respect of nuclear destruction is seminal to ecological thinking). He remains a weak and feeble lifeform in an obscure corner of a lesser galaxy. "Befouler of nest" would be more accurate, but less poetic.
Starting in the 1970s, and heavily influenced by the success of anti-nuclear and anti-NATO protests in Germany and elsewhere, Green thinking sought to marry this conservative tradition with radical left concerns such as social justice and participatory democracy, leading to a red-green alliance in many continental countries that appeared to place the Greens firmly on the left of the political spectrum. In reality, this development (and "rainbow coalitions" generally) masked the fragmentation of both left and right radicals around consumption and lifestyle preferences (cycling, craft beer, gay marriage etc), which was actually a testament to the hegemony of market-inflected libertarian thinking. By the turn of the century, Silicon Valley capitalists and chancers like Richard Branson were promoting themselves as green champions.
In the UK, the lack of proportional representation stymied a red-green alliance, as radical left activists either knuckled-down in the Labour Party or joined the Judean People's Popular Front, which has left the Greens fluttering their eyelids at LibDems uncomfortable with the neoliberalism of their Orange Book establishment (in this respect, they are in direct competition with Labour). Since 2008, being anti-neoliberal has become a way for the Greens to present themselves as attractive to both frustrated socialists and anxious conservatives, even to the point of being positioned by some media commentators as the "UKIP of the left". This is not as paradoxical as it might appear at first sight, as the psychological dynamic of both parties depends on a belief in an imminent threat to a settled order, not to mention the psephological waywardness of seaside towns.
The Greens continue to burnish their egalitarian credentials with their support for ostensibly radical policies like a citizens' basic income, without explaining how this could be achieved through economic policies that eschew growth for sustainability. A basic income is simply a mechanism that can be implemented in either a progressive or a regressive way. Without a radical reordering of society (i.e. who owns what), or a progressive distribution of the fruits of future growth (i.e. where the poorest benefit disproportionately), it will inevitably entrench existing inequalities and poverty. A basic income plus sustainability sounds radical, but its practical results would be remarkably similar to Tory policy, namely wage stagnation for the many and an increase in the social power of patrimonial wealth.
The meta-narrative of current political journalism is that the major parties are in decline, eaten away on all sides by fringe parties grabbing market share from voters disenchanted with the Westminster elite (the analogy with the supermarket sector reinforces the trope of politics as a consumption preference). The secular trend has been a decline in each of the two main parties' electoral support from 45-50% in 1945 to 30-35% in 2010. However, another way of looking at this is that varieties of neoliberalism now enjoy over 90% of the vote, if you include the LibDems and SNP. As per its standard modus operandi, fictitious competition has been introduced to a rigged market, with each brand selling the same ingredients in slightly different combinations. If UKIP have (irony of ironies) been positioned as the Aldi and Lidl of political insurgency, the Green Party is trying to be a hybrid of Waitrose and the Co-op.