"Climate Change 2007 - The Physical Science Basis" is the most comprehensive and up-to-date scientific assessment of past, present and future climate change. The report provides: the most complete and quantitative assessment of how human activities are affecting the radiative energy balance in the atmosphere; a more extensive assessment of changes observed throughout the climate system than ever before using the latest measurements covering the atmosphere, land surface, oceans, and snow, ice and frozen ground; a detailed assessment of past climate change and its causes; the first probabilistic assessment of climate model simulations and projections using detailed atmosphere-ocean coupled models from 18 modelling centres around the world; and a detailed assessment of climate change observations, modelling, and attribution for every continent.