Polling data hardly means a consistent thing from one party to another, does it? If you say you're going to vote BNP, it's like saying you're going to set fire to a pub. You'd have to get as far as the front door with a can of petrol before anybody would believe you.

A stated intention to vote Green, on the other hand, doesn't have the ring of merry threat or bravado; it has the ring of sober consideration. To test that theory, however, you would have to look at a result and compare it with a poll. This is made exceedingly difficult by the fact that the Greens are habitually called "other", lumping them together with the BNP, along with the more like-minded but factually incorrectly named Animals Count (animals cannot count) and the properly barmy Christian People's Alliance.

"Othering" actually has a sort-of specific meaning, in sociological terms, placing a person or a thing outside the scope of normality and acceptability. However, the meanings collide: when they put a political party in the "other" category, this "othering" is, by happenstance, the result.

Polls as a ranking tool are pretty boring. Maybe I'm being trivial and trying to turn psephology into Emmerdale, but I don't just want to see who wins and who loses; I want to see who wins from whose losses. In 2009 Labour was down nearly 7 percentage points (anybody who thinks they're unpopular now just has a very short memory), but those numbers weren't showing up in support for the Tories or Ukip, still less the Lib Dems, who were themselves down 1.2 percentage points (and people still liked Nick Clegg back then. Imagine!). The Greens, though, had picked up 2.4 percentage points, which, since it increased their vote share from under 6% to over 8%, was pretty significant.

However, you would have had to wait until the weekend after polling day to find that out.

This time around, the Greens are polling higher than at any point since 1989. Their share went from 3% to 8%, in a poll whose results were interpreted, by every paper apart from the Evening Standard, as testament to the fact that voters hate everybody (to put that in Westminster terms, it's a "war of the weak"). Imagine if Ukip's poll ratings had nearly tripled what manner of political flurry we would be in then. Imagine if the Lib Dems went below the Greens, which they very nearly have (in this same poll, they were on 9%); in a YouGov poll last week asking about voting intentions for the European elections, the Lib Dems were two points behind the Greens, who reached 12%.

Green candidates are not known for their readiness to despair: otherwise, they wouldn't be standing in the first place; they'd be growing marrows and practising skills for a post-oil age. Yet they are so baffled by the surge in support, on the one hand, and the complete lack of recognition or coverage on the other, that as Molly Scott Cato (prospective MEP for the South West) says: "I find it hard to believe myself that it really happened."

The Green party has changed: partly the personalities within it, partly in response to the changing world outside it. The last time its popularity was this great, it came with a message of imminent disaster; and hats off to it for getting support that way, because it's just about the most difficult route a party can take. Now, climate change has passed into the vernacular. Everybody, from the UN to the larger insurance companies, is saying how costly it's going to be – it is no longer a niche position to say we might have a problem.

At the same time, ideas that were mainly theoretical 25 years ago – solar and wind technology, community energy projects that could take whole towns off-grid – have become demonstrably workable. Half a million UK homes generate around half their energy from the sun. On a particularly windy morning last week, Germany was getting three-quarters of its power from renewables. The Greens have become the party of possibilities, not catastrophes (any party can do catastrophes).

The final factor is that the status quo is looking a lot more broken, with an oligopolistic energy market whose best offer is that it'll try not to bankrupt its customers, so long as the state is good for the shortfall, and a catastrophic housing market in which the exchange value of property has peeled away from the incomes of the people who have to live in it. The Green party's offer used to rely on dystopian foretelling on the one hand, in which we'd all fry otherwise, and utopian vision on the other, in which ideal state we would all cooperate and not compete. It used to look a bit ridiculous – but now, with the mainstream pretty much agreed about the frying, and cooperation between humans starting to look a lot less financially painful than relying on corporations to be humane, it is no wonder that the fortunes of the party are looking up.

What is a wonder is how resolutely the media ignores it. On Sunday Andrew Marr stepped back and marvelled that the Lib Dems are now fourth, behind Ukip, and didn't even mention that the Greens were joint fourth. Their successes go unrecorded. I don't think it's a conspiracy but rather a kind of constipated worldview: rogues can drop into the political terrain and be feted, because at least they'll liven it up a bit. But take a Green seriously and, before you know it, all your conversations have to change. This alternative, however – to ignore them and hope they'll go away – will leave the debate as desiccated and irrelevant as the institutions around which it revolves.

Twitter: @zoesqwilliams