Climate change is the greatest threat we face today.
Unless we take effective action - and promptly! - it will cause disruption to our food and water supplies, damage and destruction to our homes, and threaten the civilisation on which we depend for our livelihoods and well-being.
One of the most urgent things we need to do is to reduce the amount of Carbon Dioxide and other "greenhouse gases" we emit from the energy we use by switching to sources which produce practically no CO2, such as hydro-electricity, nuclear, geothermal, wind, wave, solar, and the use of Carbon Capture and Storage (CCS) to remove CO2 from burning fossil-fuels and bio-energy fuels (BECCS).
Our graphic symbolises the sources of clean energy we have available to us: our sun which directly gives us solar power, and indirectly gives us wind, wave and hydro power, and atomic energy which we harness directly in our nuclear power stations and which indirectly gives us geothermal energy.
Nuclear? But what about Fukushima? Chernobyl? Three Mile Island? Nuclear Waste? Proliferation?
In 1975 when the "Smiling Sun" symbol was created we were justified in being worried about nuclear power. If a few kilos of Uranium in an atomic bomb could blow up a whole city what would happen if a reactor containing a hundred tonnes of the stuff went wrong? Nobody knew: even some nuclear experts were concerned about the safety of the pressurised water reactors being used for power generation. Could a reactor explode like a bomb? Could it melt down through its steel pressure vessel and concrete containment and keep on melting its way through the ground beneath it, as postulated in The China Syndrome? Just days after that fictional movie opened we got an answer when a real life reactor at Three Mile Island in Pennsylvania, USA melted down. At the time, and in the immediate aftermath, the fact that the accident had happened at all, the confusion and panic over how much radiation had been released from the plant and whether to evacuate people living nearby, and the failure of the plant operators and experts drafted in to understand what was going on for several days, all tended to confirm us in our suspicions of nuclear power's dangers.
But looking back did it justify our outright rejection of nuclear power? The accident killed nobody, either directly at the time or through an increased probability of someone exposed to radiation eventually dying of cancer from it. (The increase in radiation outside the plant was less than natural background levels.) The accident could have been worse and exposed plant workers or even members of the public to harmful levels of radioactivity, and people might have died, at the time or later, but there was no evidence there could have been catastrophic numbers of casualties.
And the operation of TMI reactor #2 - along with its sister plant #1, and every other nuclear power station in the world - has to be placed in the context of electricity generation in general, which at the time was dominated almost entirely by coal-fired power stations. We should have not only been considering the possible dangers of nuclear but comparing them to the known dangers of coal: a relentless toll of death, injury and sickness in the mining industry, and sickness and death from heart and lung disease caused by coal-burning's air pollution amongst the public as a whole.
How dangerous would nuclear power have to be to be worse than coal? Forty years ago none of us lay-person activists would have had the figures to compare. But in 2013 a scientific paper by climate scientists James Hansen and Pushker Kharecha gave us some answers: if nuclear power plants hadn't existed and the electricity they generated had been supplied by coal instead, up to 80,000 more people a year would have died from the effects of the air pollution caused by coal burning: over 2 million by now.
So nuclear power would have to be horrifically dangerous to be worse than coal which, especially in the 1970s, was what it mostly replaced. Three Mile Island didn't show any potential for such dangers, but it was only one accident: were much worse accidents possible?
Chernobyl in 1986 showed that they were: a reactor apparently exploded throwing much of its radioactive contents over the surrounding countryside and leaving a burning and intensely radioactive wreck which took desperate efforts (and cost many lives) to quench and contain.
The explosion itself was caused by steam; the reactor was being used in a test (ironically to improve its safety) which was conducted hurriedly by staff who didn't understand aspects of the reactor's operation and, in particular, its ability to suddenly run out of control, generating ever increasing power. The reactor was a Soviet RBMK, designed not just to generate power but also to make plutonium for weapons, for which the steel and concrete enclosures of pressurised water reactors would be an impracticable hindrance. So when the powerful reactor suddenly surged to over ten times its normal power and its cooling water flashed to steam there was no foot-thick steel pressure vessel within a yard-thick concrete containment to withstand the steam pressure or contain the reactor contents.
Despite the desperately dangerous conditions faced by those tackling the disaster, amazingly only 28 people died of radiation effects. Unforgivably the Soviet authorities, in denial about the accident, failed to protect nearby residents by even the simple measure of distributing iodine tablets; as a result many contracted thyroid cancer, and 15 of those eventually died of it. It was also estimated that thousands, or tens of thousands of people would die prematurely of cancers caused by exposure to radiation from the accident. It is impossible to tell whether these predictions came true and, if they did, who amongst the millions of people who die of cancers anyway did so as a result of the accident. But given the number of premature deaths that nuclear power prevents by replacing coal, we would have to be having multiple Chernobyl scale accidents every year for it to be more deadly than coal. And there are no longer any reactors like those that made the Chernobyl accident possible operating anywhere in the world.
And what about Fukushima?
Three Mile Island gave only one example of what could happen in an accident in the sort of reactor with a steel pressure vessel and reinforced concrete containment which most reactors in the world have. Fukushima gave us four more examples. Each reactor (all of which were built before the one at TMI) survived seismic shocks many times more violent than they were designed to withstand, but the onslaught of the subsequent Tsumani knocked out power for the reactors' cooling pumps and as a result they overheated and melted down. Like TMI the accidents killed nobody, and are not expected to kill anyone in the long term. More radiation was released than at TMI, but if people around the plants had stayed in their homes rather than being evacuated they would have lost on average just 3 months of their lives: comparison with deaths due to coal burning are far from hypothetical since Japan has kept most of its nuclear plants closed, despite being undamaged, and is now burning coal as well as oil and gas instead with the result that far more people will die needlessly whose lives could be saved by nuclear energy.
So: since the launch in 1975 of the "Nuclear Power? No Thanks" symbol we have progressed from complete uncertainty and reasonable cause for concern about the safety of nuclear power plants, to reasonable evidence that the common types of reactor, enclosed in substantial layers of steel and concrete, pose no threat to human life even in a melt-down. The worst aspect of such accidents is that they are expensive to clear up. It takes a now-defunct design of reactor with no protective enclosure to cause even modest loss of life (and a bigger and more expensive mess to clear up). Time has also shown that our concerns about nuclear waste and proliferation were ill-founded.
And we now know that nuclear power actually saves large numbers of people's lives by displacing coal and its resulting air pollution.
Since 1975 we have also learned that the air pollution which kills people by causing heart and lung disease is not the only, or the worst effect of coal. We are now aware that climate change caused by burning all fossil fuels - coal, oil and natural gas - may be far deadlier to human life. And the ability of nuclear, along with other low-carbon sources of energy - hydro, wind, solar, wave, tide, geothermal etc - to replace greenhouse-gas emitting fuels is crucial to mitigating the problem. Whilst air pollution from coal kills around 240,000 people a year a cautious estimate for the expected effects of climate change are about 250,000 deaths/year just from from malnutrition, malaria, diarrhoea and heat stress, with upper estimates ranging all the way up to eventual extinction of all 7 billion people on this planet!
How important is nuclear in mitigating climate change, compared to other low-carbon energy sources?
If we look at how low-carbon different countries' electricity supplies are and what technologies they use we find that hydro and nuclear are far better at reducing countries' carbon footprint than wind and solar:
We can also see the carbon-intensity of countries' electricity supplies in real time at the Electricity Map website. Here again we see that countries and states with the lowest carbon intensities - the greenest on the map - use nuclear and/or hydro.
It's clear that where hydro is not available - for reasons of geography or rainfall - nuclear power is the only practicable way to effectively decarbonise electricity generation.
It's not that intermittent renewables - wind and solar - haven't been tried seriously anywhere. In Germany their Energiewende policy has seen a sizeable part of their nuclear fleet shut down, supposedly to be replaced with wind and solar, on which they have already spent over 150 billion Euros. However the energy produced by this massive investment has fallen so far short of meeting demands that Germany has been re-building coal-fired power stations, and destroying ancient forests and villages to extract more and more Lignite - brown coal: the dirtiest form of this dirtiest of fossil fuels - to supply them.
The air pollution they produce kills more than 4,000 people every year, and Germany has given up on meeting its 2020 emissions reductions targets.
Almost 10% of the country's CO2 emissions - and a proportion of the death and sickness it causes by air pollution - could have been averted if Germany had not been shutting down its nuclear power stations:
And it's not just Germany: Japan has re-opened only a handful of its nuclear power stations, despite them having been inspected and found to be quite safe. It is now burning gas, oil and coal. In the USA nuclear power plants are being shut down and replaced by gas fired generators. In Britain, France, Sweden, Swizerland, South Korea and elsewhere there is pressure to close existing nuclear power stations, and opposition to building new ones. And we - the Smiling Sun badge/button and T-shirt wearers, the Greenpeace and FoE supporters and Green Party voters - are the people making this happen. Germany's Green Party are responsible for their country closing down its nuclear plants, despite the resultant increase in CO2 emissions, air pollution, and consequent deaths and sickness. Greenpeace, Friends of the Earth, Green Parties, the Sierra Club and others in the anti-nuclear movement have been so succesful in sustaining and nurturing fear of nuclear power that the almost 20,000 people killed and massive damage caused by the Great East Japan earthquake and tsunami have been forgotten, eclipsed by an accident which caused property damage but zero fatalities and which would have gone unnoticed if it hadn't involved anything nuclear. Worse, the fear which we, the anti-nuclear movement, have fostered over the decades, caused panic amongst those living around the Daiichi power plant resulting in an evacuation which lead to the deaths of more than 1,600 people from stress and other illnesses and which still blights the lives of evacuees who have not only lost their homes but live in fear of levels of radiation which are below background levels for many parts of the world and which results in people living in virtual self-imprisonment, instilling their fears into their children who they allow to play outdoors for only a few minutes each day.
How did we get to this state?
In the 1970s we - quite reasonably - wanted to protect ourselves, our children and our fellow humans from the then-unknown hazards of nuclear power. But somehow we have created a dogma which fails to get things in proportion, fails to adapt to change, is currently killing tens of thousands of our fellow humans every year, and is stopping us responding effectively to the greatest peril we have ever faced: climate change — as a result of which we are ensuring that many millions more will die.
When world oil prices sky-rocketed due to the 1973 oil crisis France responded by building nuclear power stations, installing 56 reactors over a period of 15 years and now producing over three-quarters of France's electricity. Over a similar period Sweden also built enough nuclear power to supply 35-40% of the country's electricity.
If the world had responded to the climate change crisis the way France did to the oil crisis we could by now have almost completely decarbonised our electricity and be busy electrifying space-heating, transport, and other current uses of fossil fuels.
We might have managed to keep the proportion of CO2 in the atmosphere below 350ppm and have a chance of limiting global temperature rise to 1.5C. Instead even 450ppm is the most ambitious target the IPCC now considers. Even our electricity is still massively carbon-intensive and we are decades away from decarbonising even that. CO2 levels have passed 400ppm and continue rising, while global temperatures are on course to rise by 2 or 3C.