BRUSSELS (AFP) - In a shift since the last European Parliament elections, mainstream parties have adopted climate change as a rallying cry - spurred in part by a wave of student strikes.
With the "Fridays for Future" protest due to continue in cities across the continent on the second day of voting, the growing consensus for urgent climate action has raised hopes of cross-party cooperation.
But there are also fears populists could torpedo this if they make strong gains.
A Eurobarometer poll shows climate change is now a leading concern for European Union voters, not far behind economic issues and rivalling worries about migration.
And, amid weekly protests over what activists now term the climate emergency, Europe's mainstream political parties have finally grasped the issue.
"It is fair to say that climate and environmental policies now are embedded in all the political parties," said Mr Dara Murphy, campaign director for the European People's Party (EPP), the largest bloc in the outgoing European Parliament.
"If you compare it to 2014, it has really become one of the top issues in the European elections," Mr Murphy told AFP from his native Ireland after trips to other EU countries.
He said the centre-right EPP added climate change to its campaign programme over the last two years based on research showing growing environment concerns.
But analyst Stella Schaller and Laurence Tubiana, an architect of the Paris climate deal, said global warming's rise to major political prominence is more recent.
"We saw the debate tipping in the last four to six months," Ms Schaller, analyst at Berlin's Adelphi environmental policy think tank, told AFP.
The shift has occurred, she said, as droughts, fires and floods hurt farmers, scientists multiply dire warnings, street protests increase and the media highlight it all.
'FRIDAYS FOR FUTURE'
Among the loudest proponents for urgent action are the recent "Fridays for Future" boycott of classes worldwide, with more mass protests set for Berlin later on Friday (May 24).
Ms Greta Thunberg, the 16-year-old Swede behind the boycott, has warned politicians in Brussels they will be "remembered as the greatest villains of all time" if they fail to act.
Mr Udo Bullmann, who heads the Socialists and Democrats in the assembly, told AFP there is "an historic momentum" for decisive action thanks in part to the student activists.
"We hear their call," Mr Bullmann said in an e-mail.
"Climate change has never been as central to a European election and to our campaign as this time," the German political leader added.
His centre-left group, the second-biggest in the outgoing Parliament, has reformed its agenda in the past two years to meet the climate challenge in a "holistic" way.
Mr Bullmann said the agenda sought to ensure the poor and unemployed do not carry the burden and to avoid fuelling unrest like the yellow vest protests in France.
The Socialists reject an economic model Mr Bullmann says is "driven by greed and based on exploitation of people and the planet".
The EPP's Mr Murphy also called for supporting the most vulnerable in society while boosting research and easing the "regulatory burden" on small and medium-sized firms.
Mr Murphy said climate has risen to the fore because it is a cross-border policy challenge also linked to economic problems and migration, which is partly driven by drought.
He said the problem represents an opportunity for Europe to lead, such as on job-creating, low-carbon technology.
'JURY STILL OUT'
Echoing scientists and the student activists, Mr Bullmann said: "We have only 10 years left before the damage becomes irreversible."
Under the 2015 Paris deal to limit global warming to well below 2 deg C above pre-industrial levels, the 28-nation EU has pledged to cut greenhouse gas emissions by at least 40 per cent by 2030, compared to 1990.
But many scientists and climate activists say Europe must sharply raise its ambition.
The UN Intergovernmental Panel for Climate Change (IPCC) warned in October that warming is on track towards a catastrophic 3 deg C or 4 deg C rise, and avoiding global chaos will require a major transformation.
But there is also a powerful backlash.
Joining some other far-right groups, the Alternative for Germany (AfD) has discovered climate change denial as a key topic in their campaign for the May 23-26 elections.
They have their sights on voters who see ecological issues as an elitist concern that kills jobs and hurts industry.
Berlin-based analyst Ms Schaller voiced fears "liberal and conservatives groups will water down proposals" and pander to nationalists, as conservatives did with migration.
But the EPP's Mr Murphy insists "we will not be doing business with the far-right" on climate or other issues.
Greens candidate Bas Eickhout expressed guarded hope for cross-party cooperation in the next parliament on issues like carbon pricing, cutting aviation subsidies and allocating more funds to environmental issues.
But Mr Eickhout, a candidate for the new European Commission, asked whether the centrists have made an "intrinsic change" on climate or are simply trying to win seats.
"The jury is still out," the Dutchman told AFP.