There is now widespread consensus that the Earth is warming at a rate unprece- dented during post hunter-gatherer human existence. The last decade was the warmest since instrumental records began in the nineteenth century, and con- tained 9 of the 10 warmest years ever recorded. The causes of this change are increasingly well understood. The Third Assessment Report of the Intergovern- mental Panel on Climate Change, published in 2001, goes further than its pre- decessors, stating that “There is new and stronger evidence that most of the warming observed over the last 50 years is likely to be attributable to human activities”, most importantly the release of greenhouse.
