There is overwhelming evidence that the average temperature of the earth is rising and we have understood the contribution of greenhouse gases to that process for 150 years. Given the potentially, and increasingly likely, disastrous consequences the precautionary principle requires that we take action now to reduce the burning of fossil fuels. The Summary for Policymaker,   Working Group I contribution to the IPCC Fifth Assessment Report is now available. In each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. “Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water…