Greening the planet?

Abstract

In 1896 Swedish scientist Svante Arrhenius addressed a very important question: Why is the Earth a habitable temperature for humans and other forms of life? Why isn’t it too cold? The answer (building on the work of the British scientist Tyndall earlier in the century) was the greenhouse effect. He even did a quite accurate projection of what double preindustrial levels of CO2 would do to planetary temperature. What he would not have known was the detailed history of planetary temperature for the previous hundreds of thousands of years – in particular that the last 10,000 years were an unusually stable period of global climate and temperature. During those ten millennia, much of modern civilization (agriculture, human settlements) developed, and all ecosystems adjusted to a stable climate.