In conservative Bavaria, Greens doubled their vote in state elections to become the second largest party. In local elections in Belgium, record scores of more than 30% won them several Brussels districts and left them runners-up overall. In Luxembourg, they increased their tally of MPs by 50%.

Elections in three European countries last weekend suggest that as the continent’s historic mainstream parties plummet in the polls and struggle to see off the far right’s challenge, for liberal-minded voters the Greens are looking like an answer.

Offering a pro-EU stance, a humane approach to migration and clear positions on existential issues such as climate change, biodiversity and sustainability, Green parties in several countries are now polling higher nationally than the traditional centre-left.

“They represent a clear place where people can go who are frustrated with the traditional mainstream parties but who don’t like the far right,” said Alexander Clarkson, a lecturer in European studies at King’s College London.

“They offer a very clear counter-model to the positions and arguments of parties like Germany’s AfD. Also they’ve been around for a while now, more than 40 years, and they’ve governed responsibly both locally and regionally. They kind of look like the adults in the room.”

In Germany, where the Greens partner parties from the centre-right to the hard-left in nine of the 16 state governments, recent national polling put the party ahead of the centre-left SPD, Angela Merkel’s coalition partner, with a 17%-plus share of the vote, compared with 8.9% in last year’s federal election.

In the Netherlands, the GreenLeft party, which boosted its tally of MPs from four to 14 in general elections last year, has also advanced to second position in the polls since then, from 9% to nearly 13%.

Green parties score particularly highly among professional, often young, relatively affluent and generally urban voters, analysts say. “If you look at the demographics, many are what you’d once have called typical lefty voters,” said Jon Worth, a candidate for the German Green party in next year’s European elections.

“They have a young, energetic leadership and a different style of doing politics – straight-talking, acknowledging the limits of what can and can’t be done … A mix of ideology and pragmatism that puts individual, everyday choices at the heart of politics again. It’s not a party driven by a comms strategy; there’s no spin.”

Growing environmental awareness among many voters is also plainly a factor. After a summer of record-breaking temperatures across Europe during which wildfires blazed in the Arctic, it is hardly surprising that a movement that since the 1980s has warned of the dangers of climate change is winning greater support.

But if the Green wave has come mainly at the expense of traditional centre-left social democratic parties, whose support has plunged across Europe to the point of near wipeout in countries such as France and the Netherlands, the movement also increasingly appeals to substantial numbers of disillusioned centre-right voters.

The rise of the far right has shifted national debates, dragging the rhetoric of many mainstream conservative parties – particularly on immigration – further and further to the right and alienating their more liberal-minded voters.

In Bavaria’s state election, the centre-left SPD lost 210,000 voters to the Greens. But the ecologists gained very nearly as many – 180,000 – from the centre-right CSU, which had tacked sharply to the right in an attempt to win back votes from the far-right AfD.

Perhaps crucially, although the German Greens were in government as junior partners in Gerhard Schröder’s Social Democrat-led coalition from 1998 to 2005, few European Green parties have governed nationally since the 2008 financial crash.

“They have not had to take the big national decisions around austerity, have not been sullied in the same way as the main centre-right and centre-left parties that are so implicated in the aftermath of that crisis,” said Fabien Escalona, a French political scientist at Sciences Po Grenoble.

Escalona also noted that Green parties appeared to be doing particularly well in relatively prosperous countries, where the effects of austerity had not been felt so severely but where migration had become a major political issue. Elsewhere, a more radical left was more popular, he said.

Europe’s Greens have experienced similar polling surges, most recently after the 2011 Fukushima nuclear disaster in Japan. But the trend away from a traditional right-versus-left, socio-economic view of politics towards a more ideological debate could mean this one is more structural.

The German Greens’ slogan in Bavaria was “Rather than spread fear, give courage,” a message that the movement sees as key to its growth and vital to counter what the party’s co-leader Robert Habeck calls the “brutalisation” of political discourse.

Monica Frassoni, co-chair of the European Green party, said the results showed success could be won “by putting hope over fear, and compassion over hate”.