At the basis of these changes is the demand for more and more energy to drive our industries, to heat our homes and to power our transport and communications. All known ways of generating this
energy affect the earth in one way or another, by using up the energy stored over geological timescales as coal or oil and by the pollution they cause. These sources of energy will ultimately be exhausted, but if we continue to rely on them, we may well cause irreversible climate change. It is therefore a matter of urgency to find safe and clean ways of generating energy. At the same time, it is necessary to reduce and if possible, eliminate all the other sources of pollution.