Ask a stupid question and you'll get a stupid answer. That's what happened in the Italian referendum on nuclear power on Monday, where voters overwhelmingly backed anti-nuclear campaigners' demands to block any new atomic power in Italy. Referendums are not a good way to set energy policy, nor many other aspects of national policy either – if a referendum were held on capital punishment in Britain, a hefty majority would support bringing back hanging.

The Italian result needs to be seen in the context of a wider European political debate where anti-nuclear campaigners – led by the greens – have been successful in discrediting nuclear power. No doubt a referendum in Austria would have the same result, while the governments of Switzerland and Germany have already decided to phase out their nuclear plants altogether in response to the Fukushima accident in Japan.

As a lifelong environmentalist, and author of a 2009 book which laid out the terrifying prospects of uncontrolled global warming, I cannot help but feel that the decisions of the German and Swiss governments rank among the worst climate-related policies of recent years. Carbon emissions cannot do anything other than rise as a result of phasing out the continent's largest source of zero-carbon power – and doing this just a week after the International Energy Agency reported that 2010 carbon emissions rose to the highest levels ever is little short of criminal.

There is perhaps a certain discomfort about the fact that one of the best options for tackling global warming just so happens to be a technology that greens had spent decades opposing before climate change even hit the agenda. I have lost count of the number of times I have heard green groups insisting that climate change is the "greatest challenge ever to face humanity". Yet their refusal to reassess their inherited positions against nuclear power suggest that none of them actually believe what they are saying – or that most environmentalists are prepared to take refuge in ideologically motivated wishful thinking even when the future of the planet is at stake.

If the German greens really took climate change seriously, they would instead be pushing for a phase-out of coal – which generates by far the largest proportion of the country's power and consequent carbon emissions – from Germany's electricity grid. Instead, the new nuclear phase-out plan will see a hefty 11GW of new coal plants built in years to come, with an additional 5GW of new gas. The only way emissions from these plants could be controlled would be through "carbon capture and storage" (CCS) – yet Greenpeace in Germany has already mounted a successful scaremongering campaign against this new technology, helping to ensure that future fossil emissions will go into the atmosphere unabated.

Unfortunately, the new coal plants will spew out more radioactivity into surrounding areas than any of the German nuclear plants would have done if they stayed open, thanks to the fact that trace isotopes in coal escape up power station chimneys. That all of this has come about in response to Fukushima – a non-fatal accident which has so far injured no one, not even the workers who have bravely battled to stabilise the tsunami-stricken reactors – elevates irrationality to a guiding principle of political policy in countries which supposedly pride themselves in taking scientific rationality seriously.

Indeed, it would be far more rational on a risk-precautionary basis to phase out Germany's organic farming sector, given that the recent E coli outbreak – now traced to organic sprouts produced on a farm in Lower Saxony – has killed nearly as many people as Chernobyl (36 at the time of writing, with 700 or more suffering permanent kidney damage). I have not of course heard any suggestions to this end from the German greens. And just imagine the hullaballoo had the sprouts been genetically modified instead of the "healthy" organic option.

The German government insists that the nuclear phase-out plan is entirely compatible with its emission-reduction goals. Yet this is the same government which recently extended subsidies for loss-making coal mines until 2018. It also flies in the face of mathematical logic: in 2008 Germany relied on nuclear for 23 percent of its electricity. Renewable generation in Germany has increased substantially in recent years (to 17% in 2010) – yet to ask renewables to replace nuclear as well as fossil fuels will make the achievement of Germany's climate goals doubly difficult, and therefore twice as unlikely to actually happen.

The silliness does not stop there. Much of Germany's renewables investment has been in solar photovoltaics in recent years, thanks to extraordinarily generous feed-in-tariffs. Yet these solar roofs are so expensive that they cost more than €700 per tonne of carbon abated, compared to a carbon price in Europe of €15 or less. One expert study suggests that the whole solar experiment up until this year has already landed German energy consumers with a €120bn liability for the next two decades – this in order to generate a mere 2% of the country's electricity, or less than a single large nuclear plant.

In contrast, the UK's energy policy actually looks quite sensible these days. There is a broad ambition – articulated by the excellent Climate Change Committee – to decarbonise the entire electricity sector by 2030, by deploying nuclear and renewables in roughly equal proportions of 40% or so. There is a lot of sense also in Britain's policy of ramping down feed-in-tariffs for solar PV, which cost the Earth while doing little to reduce emissions in this cloudy northern country. Unlike the UK, however, Germany has gone around trumpeting its new policy as worthy of emulation by other nations – let us hope for the sake of the climate that no-one follows down the blind alley led by the German greens.

• Discuss the future of the green movement with Mark Lynas in London on 6 July