This document contains the summary for Policymakers: The Science of Climate Change - IPCC Working Group I.

It details the following key features:
1. Greenhouse gas concentrations have continued to increase
2. Anthropogenic aerosols tend to produce negative radiative forcings
3. Climate has changed over the past century
4. The balance of evidence suggests a discernible human influence on global climate
5. Climate is expected to continue to change in the future
6. There are still many uncertainties
Considerable progress has been made in the understanding of climate change1 science since 1990 and new data and analyses have become available.