'Climate change' describes the variability of weather systems over extended periods of time. It occurs as a result of complex and poorly understood natural cycles, but may also be influenced by human activity. Most of the current debate over climate change has become synonymous with the extent of 'anthropogenic (human-induced) global warming'. Most citizens accept unquestioningly that industrialised society is causing unprecedented and potentially catastrophic changes to global weather patterns. Such views have become part of the conventional wisdom spread by environmentalism. It is also widely accepted that taking measures to drastically reduce our burning of fossil fuels - starting with the targets set in the Kyoto protocol - will mitigate these changes. Although many factors affect climate change, it is the enhanced greenhouse effect that dominates current debates. However, life on earth depends on the natural greenhouse effect. Gases such as carbon dioxide, methane and water vapour, which are present in the atmosphere, allow energy from the sun to reach the earth's surface, but reduce the rate at which heat is lost into Space by infra-red radiation. This is a natural process, without which the Earth's average surface temperature would be about 33°C cooler than it is today, and plants, animals and humans could not live. Currently, the debate primarily focuses on: i) the extent to which anthropogenic activity, such as the burning of fossil fuels, and land use changes have led to 'enhanced' climate change, ii) the effects this will have, and iii) what measures, if any, should be taken to mitigate or adapt to any effects. We believe that a balanced debate based on reason and sound scientific evidence is called for, before putting drastic and far-reaching policies into effect. A number of questions surrounding the science behind the climate change debate pose challenges to the notion that there is scientific consensus on climate change. Instead of blindly or ideologically invoking the 'precautionary principle' as a justification for the Kyoto protocol, we should take a step back and consider all the possible consequences, both of climate change and of the measures taken to prevent it. There are severe implications for future energy supplies in both the industrialised and developing worlds. Fossil fuels - coal in particular - represent an abundant, cheap source of energy. Any move away from their use not driven primarily by market forces would increase the cost of energy for all. A move towards increasing use of nuclear fusion - the only safe, proven, low-emission technology available to meet base load requirements - has been held back by deep-seated opposition from some quarters. Wind and solar power are being promoted because of their fully renewable nature. However, they suffer from intermittency and cost constraints and are unlikely to be able to fulfil more than a fraction of demand without maintaining conventional backup generating capacity. For transport, much is made of the potential of bio-fuels (ethanol, diesel and, more recently, butanol), but these are not necessarily the panacea some would believe. There are also enthusiasts for hydrogen to replace conventional fuels, but there is not yet a convincing strategy to generate, distribute, store and use such a difficult material. The debate about energy generation and use, driven to a significant degree by the current received wisdom on climate change, is in a state of flux, and clear, rational analysis of all existing and future options is called for.