The dispute is getting personal and much closer to the political bone with the fallout potentially damaging the whole idea of 'environmentalism'

The war of words between the pro- and anti-nuclear environmentalists shows no sign of ending, with those writers in favour – George Monbiot, Mark Lynas, Fred Pearce and Stephen Tindale – now slugging it out with those campaigning against – Jonathon Porritt, Tom Burke, Tony Juniper and Charles Secrett. Everyone is pretending to be quite grown-up, polite and cool, but actually it's getting vicious.

Apart from a few gratuitous insults on either side, the dispute that has rumbled on for a few years has so far been largely technocratic and conducted with political and personal respect. In the latest skirmishes, the four former heads of Friends of the Earth (FoE) politely wrote to the prime minister advising him to drop nuclear power on cost and other grounds; whereupon the hacks also wrote to No 10 saying this advice undermined government climate change policy. Over the next month Porritt, Burke & co will issue four or five more intellectual blasts, and will convene a press conference, and we can expect the hacks to respond.

Until now it has been a classic "fundi" and "realo" split with the pros' (the realos) desperation to address climate change set against the antis' (the fundis) conviction that nuclear takes too long, is too expensive and won't actually work.

But now, the dispute is getting personal and much closer to the political bone with the fallout potentially damaging the whole idea of "environmentalism". First we have Lynas suggesting that nuclear protesters are not really environmentalists at all, then Monbiot doubted Burke's commitment to the environment – despite his 40 years' active service. Now, in an extraordinary exchange of emails between Monbiot and Theo Simon – who is one half of the renowned radical protest band Seize the Day – all opponents of nuclear power are said to have made their arguments "with levels of bullshit and junk science".

Here's part of Monbiot's letter, sent to Simon even as he was occupying a farmhouse in protest against the way that EDF were going about the works at Hinkley:

The uncomfortable fact is that the opponents of nuclear power (among whom I numbered until recently) have justified their position with levels of bullshit and junk science very similar to those used by the climate change deniers, and Stop Hinkley is no exception. When I wrote to Katy Attwater [a Stop Hinkley spokeswoman], expressing my concerns about the quality of the scientific evidence on their site, she told me 'I have no faith in the scientific peer review process as it currently works.' Just like James Delingpole, David Bellamy etc when it comes to climate science.

Monbiot then begs Simon to give up his protest, which he says is both "wrong" and dangerous:

We need you too much for the battles that need to be fought. God knows there are enough of them. But the inevitable result of this one, if it succeeds, will be to raise our greenhouse gas emissions, help threaten life on earth and compromise the life chances both of future generations and of people living now in countries poorer than our own. That is not what you or any of us began campaigning for. But as the results of both the German and Japanese experiments demonstrate, it's now clear that this will be the legacy of anti-nuclear campaigning. Please think again before you counteract all the good work you've done on other issues.

You can imagine how this appeal from the heart went down with Simon, who last month was given a conditional discharge of six months for the Hinkley protest and has been putting himself on the physical frontline for years. Describing Monbiot's email as "patronising", he waited a few days and then wrote back with a series of points that the pro-nukers have not so far addressed - like the assertion that the technology demands a stable and continuous technocratic society to exist for centuries, and entrenches power in the hands of a state-protected, unaccountable and ruthless elite.

Here's some of his letter:

We need more than ever to champion a vision of the kind of creativity which a democratic revolution would rapidly liberate. Nuclear … can give no ultimate assurance of it's safety or its costs. Neither can it demonstrate the kind of long-term resilience which may prove necessary if runaway climate change does, in spite of our efforts, develop. Resilience is to my mind something which we should be designing into our energy production plans now, as the future is so uncertain for our children. Nuclear requires a stable and continuous technocratic society to exist for centuries.

He goes on:

[Monbiot and other writers'] public promotions of nuclear have disorientated and disheartened the green movement and the left, while finding a willing audience among the broader middle-class who welcome a chance to salve their guilt about energy-intensive lifestyles with the reassuring news that 'apparently nuclear's OK now, and it's the only way to solve climate change'. You can't really be surprised – or even dismayed - that so many people respond emotively to your propagandising for nuclear. From their point of view you seem to have become a one-man pro-bono PR company! In the letter you just co-authored to Cameron you suggest that nuclear would be a lot cheaper and better by now if Porritt and FoE etc hadn't 'devoted decades' to fighting it. Well they did. Lots of people did. Personally I'm proud of it, even if I regret that our political naivety, coupled with the defeat of working-class representation in that decade, meant that capitalism and it's appetites continued unabated. If we had moved in a more rational direction back then, renewables and other energy options could also have been a lot further developed by now, and the fabled 'energy gap', which you say we need nuclear to fill, might look a lot smaller.

Monbiot, who is offline until April 16 after becoming a new father, has yet to reply.

We are starting to get to the heart of what it means to be green today. One vision can justify a corrupt and odious state if it can make an odious technology work to overcome a terrible danger. The other argues that there are far better ways to achieve the same end without the resulting damage to society and the long-term dangers that the technology entails. The questions raised are profoundly difficult and need to be debated, but personal attacks are inflammatory and really help no one.