 And even when you have a worst case type accident like a Chernobyl or a slightly less bad accident like a Fukushima, the consequences are serious but manageable. At Fukushima, nobody has died from radiation poisoning and it's quite likely that nobody ever will. So to phase out an entire low-carbon power sector as a response to a non-fatal accident doesn't seem to me to be entirely logical. Well no energy technology is completely benign. So coal-fired power stations as we know cause climate change, they cause all sorts of health impacts, they are the worst possible option. Whereas wind and renewables are much more benign but wind farms still kill birds and they still affect landscapes and people in ways that people find negatively appealing. I think that nuclear is actually one of the most environmentally friendly technologies for a whole host of different reasons. It's really the only large-scale source of sustainable base load power which is always available, unlike renewables which are intermittent and have to have backup and that backup will still be predominantly from fossil fuel. And the other main source of base load of course is hydro and hydroelectric power means damming up river systems and it causes negative effects on ecosystems. Nuclear power doesn't do that. I think the German switch on energy policy is perhaps the most environmentally irresponsible decision that a government has made in Europe over the last 10 years. What Germany is doing is closing down its largest source of zero-carbon power and replacing it with a much smaller source of zero-carbon power which will have the unintended consequence of increasing coal consumption and that will thereby cause more pollution, it will cause more cancers, it will spread more radioactivity from the coal ash and the smoke and I can't see any environmentally responsible reason for doing that and the fact that it's the Greens who are calling for this policy speaks volumes to me. I don't consider those kinds of Greens to be environmentalists. But what should the Germans do then? Well I mean I actually think the country with the best energy system is probably Sweden which has a mixture of hydroelectricity and nuclear and some renewables as well. Obviously we have to connect up all of the different countries which have different power sources. The North Sea is an enormous resource of offshore wind. Onshore wind is viable in some locations too but to be honest countries like Germany, Poland, these are countries which don't have enormous renewable resources. You can't run them on solar power, either import solar power from the deserts of North Africa which is one of the proposals. Or you have to essentially fall back on nuclear or fossil fuels and I think what's going to happen with closing down nuclear is going back to fossil fuels. So that's what really worries me as an environmentalist and somebody who cares about the climate. Can you explain the concept of planetary boundaries? Well the idea of planetary boundaries is to try and have a more scientific definition of sustainability. So what actually matters to the planet? This isn't my concept, it was developed by a scientific team led by Professor Johan Rockström in Sweden and a real stellar cast of different scientists in different disciplines around the world who published a paper in Nature about planetary boundaries back in 2009. And their initial proposal is that there's nine planetary boundaries, seven of them have quantified limitations so they actually put numbers to them. But the conceptual model is that if you push the earth past certain tolerance limits in climate change or biodiversity or the water system or whatever then you could go over a tipping point and crash into a different unsafe space. And so the idea is to put a boundary beyond where it's uncertain and in the safe zone essentially so that we can try and run the planet sustainably without going over any of these tipping points which we may not be able to get back from. But I think the point of responsible and financially sustainable investment is to read where things are going in the future and to get in there early and to get into the right kinds of technologies which are going to become more important. And I don't think there's any doubt that sustainable technologies that renewable power sources, hopefully nuclear and some of these other areas are going to become more and more important as governments increasingly do regulate for sustainable growth within the context of the planetary boundaries.