Earlier this month, the German Greens unveiled an election poster designed to reassure voters who might be wary of their environmental radicalism. “Economy and climate without crisis”, went its slogan, suggesting that ambitious carbon reduction targets could be met without undue pain for jobs and industry. Days later, ecological crisis struck, in the form of the devastating floods that have overwhelmed western Germany, and parts of Belgium and the Netherlands. More than 190 people are so far known to have died, following flooding of an intensity and scale that has shocked scientists. The record levels of rain in north-west Europe followed record-breaking heat in the Americas. Extreme weather events are becoming the new normal, as climate models have long predicted. But some of the recent spikes have outstripped scientific predictions.

The eventual impact of the floods on Germany’s September election remains to be seen. But this disaster, which the country’s main political parties have broadly agreed was related to global warming, has thrust the climate crisis to the forefront of the campaign. On Sunday, Angela Merkel, who is standing down as chancellor, insisted that Germany needed to “up the pace in the fight against climate change”. Less impressively, the conservative frontrunner to succeed her, Armin Laschet, was caught on video sharing jokes with bystanders during a visit to a flooded town. As the president of North Rhine-Westphalia, one of the worst-hit states, the leader of the Christian Democratic Union can make amends by getting to the bottom of a lethal failure to translate satellite warnings into evacuations on the ground.

Anguished debate in Germany is understandably focused on why, given the increased frequency of flooding as a result of the climate crisis, more efficient early warning systems were not in place. But the floods also underline the vital longer-term importance of September’s poll. Germany is Europe’s most powerful and influential state. As nations face up to the hard choices involved in meeting ambitious net zero targets, the timing and context means that the post-Merkel election will be a bellwether for green political hopes throughout Europe and beyond.

Having briefly led in polls during May, Germany’s Greens have endured a difficult few weeks. The party’s candidate for chancellor, Annalena Baerbock, has suffered a series of political embarrassments, including allegations of plagiarism and overembellishing her CV. Though they remain on course to finish second to the CDU, the Greens have so far failed to seize the moment to make the case for a step change in levels of green investment in Germany, and at EU level. Meanwhile, the CDU’s manifesto, published last month, shows little sign of the economic radicalism necessary to deal with the climate emergency. Instead, Mr Laschet seeks to restore Germany’s constitutional debt brake as part of a post-pandemic return to fiscal conservatism. The stakes of this debate are enormous. As well as learning to cope and adjust to extreme weather events linked to global heating, there is a need to treat them as a warning of even worse to come if the world does not properly invest in a green future. In the autumn, Germany has an opportunity to give a lead.