For more than four decades, opposing nuclear power was as central to the identity of the Green party of England and Wales as opposing nuclear weapons. At its recent conference, that changed. Members voted to scrap the party's "blanket opposition to nuclear fission," replacing it with a policy that allows elected Greens to weigh new reactors against other low-carbon options, rather than rejecting them outright. The shift does not mean the party is embracing atomic energy.

Offshore wind, onshore wind and rooftop solar remain its preferred routes to decarbonising electricity. But Carla Denyer, a Green MP who once called nuclear "incredibly slow and incredibly expensive" during a 2023 climate debate, now argues that existing plants deserve to keep running, since much of their carbon cost was already spent on construction decades ago. "This evolution of our policy does not commit the party to backing new nuclear, but accepts this power source is here to stay for now, while we transition to electricity generation based primarily on renewable sources," she said. Not every senior figure has caught up with the mood in the conference hall.

Zack Polanski, the party's leader, has likened investment in new reactors to "creating a fax machine," and former co-leader Adrian Ramsay argued last year that money spent on the Sizewell C project in Suffolk would be better directed toward insulating homes across Britain. Supporters of the motion, including Eugene McCarthy of the campaign group Greens for Nuclear, countered that the scale of the climate emergency leaves no room to rule out any proven low-carbon technology before examining it. The debate echoes arguments playing out well beyond Britain, from Germany's abandonment of nuclear power to France's continued reliance on it for most of its electricity, and to new reactor ambitions in countries like South Korea and Kenya.