It is over three years since the drafting of text was completed for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). In the meantime, many hundreds of papers have been published on a suite of topics related to human-induced climate change. The purpose of this report is to synthesize the most policy-relevant climate science published since the close-off of material for the last IPCC report. The rationale is two-fold. Firstly, this report serves as an interim evaluation of the evolving science midway through an IPCC cycle – IPCC AR5 is not due for completion until 2013.
Secondly, and most importantly, the report serves as a handbook of science updates that supplements the IPCC AR4 in time for Copenhagen in December, 2009, and any national or international climate change policy negotiations that follow.