Green and socially liberal parties are the rise across Northern Europe. From Britain to Berlin, their electorate is composed of students and young urban professionals who lean left on social issues but do not care for the welfarism and trade union socialism of traditional labor parties.

State elections in Berlin, Germany were closely watched this weekend for a Green election victory. Bündnis 90/Die Grünen won 17.6 percent of the vote, behind the major party Social Democrats and conservatives but ahead of the liberals and far left which both lost support.

Some of the new Green party voters come from the Social Democrats who retained their majority despite losing votes; some of them come from the pro-business Free Democrats who didn’t make the election threshold.

The Free Democratic Party, Chancellor Angela Merkel’s coalition partner on the federal level, has performed poorly in recent state elections after it claimed an unprecedented 14.6 percent share of the vote nationwide in 2009. The liberals’ popularity has diminished since with college educated urban voters in particular defecting to the left.

Local elections in Saarland in 2009 may have been a harbinger of a new political constellation in Germany where the Greens refused to cooperate with the Social Democrats and the far left in favor of an alliance with liberals and conservatives. In 2008, they had previously entered a coalition with the Christian Democrats in Hamburg.

This year, the Greens tripled their share of the vote in Rheinland-Pfalz and won the prime ministership in Baden-Württemberg, once a conservative stronghold. Their candidate, a 62 year-old former chemist, belonged to the centrist wing of the Green party and profited from an anti-nuclear sentiment that swept Germany in the wake of the Fukushima nuclear power plant disaster in Japan in March.

In Denmark and the Netherlands, left of center parties similar to Germany’s Grünen also appeal to cosmopolitan young working people who reject the old left’s reinvigorated market criticism but are appalled by the right’s willingness to embrace populist anti-immigrant and security policies at the same time. They are united around themes of environmentalism, individualism and minority rights.

In Denmark, the Radikale Venstre represents social liberals who oppose the main liberal Venstre‘s alliance with the far-right Danish People’s Party. In the Netherlands, the intellectual D66 and progressive GroenLinks together accounted for 13.5 percent of the vote in last year’s parliamentary elections. Both oppose the hardline immigration policy of the liberal-conservative government but favor market driven entitlement and labor law reforms.

The Liberal Democrats in Britain aren’t willing to admit yet that they represent a similar kind of cosmopolitanism. The reason is that part of their leftist electorate doesn’t want to commit to such a direction. As The Economist put it, when they voted Liberal Democrat last year, “they assumed it was a social democratic party with civil libertarianism and Europhilia thrown in; a Labour Party for university towns and upmarket suburbs rather than the industrial heartlands.”

The Liberal Democrats’ alliance with the Conservatives proved their voters wrong. Party leader Nick Clegg, now deputy prime minister, led them toward centrist, classic liberalism, much to the dismay of rank and file liberals who “don’t really believe their party is either liberal in the classical sense or even ideologically neutral between right and left.”

This could be a problem for other Northwest European Green parties as well. Their members tend to be more leftist than their voters who are generally skeptical of “big government” welfare schemes. Moreover, part of their base has pacifist roots which could complicate their ability to govern responsibly.

The German Greens realized this in 1998 when they entered a coalition with the Social Democrats just before NATO intervened in Kosovo. Green party parliamentarians weren’t happy with the war and outright hostile to sending German troops to Afghanistan in 2001. GroenLinks in the Netherlands found itself in a similar predicament this year when it failed to enthuse party members for an Afghan police mission it endorsed.