This WMO information note is the first in a series that will aim to make the science underlying the weather, climate and water issues addressed by the World Meteorological Organization (WMO) more easily accessible to the general public. The science of climate change continues to advance through the accumulation of additional data and observations and new studies and analyses. The peer-reviewed scientific literature that draws on these data and studies are assessed by the WMO/UNEP Intergovernmental Panel on Climate Change (IPCC), which will issue "The Physical Science Basis" volume of its Fifth Assessment Report in September 2013. This public information note will be updated to reflect the IPCC findings.