As has been widely reported in the press, the Intergovernmental Panel on Climate Change has released the first volume of its Fifth Assessment Report, Climate Change 2013: The Physical Science Basis. The IPCC is a worldwide group of scientists established by the United Nations that has for the last few decades been collecting and reporting the scientific consensus on climate science. Working Group 1 — whose report was released this week — reports the state of science on what is happening. Working Group II will report on impacts and adaptation — that is, steps to address or to moderate impacts. Working Group III will address mitigation — that is, steps to avoid climate change at all. This Fifth Report being issued now updates the Fourth Report, issued in 2007.
The IPCC issues a Summary for Policymakers with each piece of the report. That summary describes the evidence of warming as “unequivocal.” It also states:
Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes (Figure SPM.6 and Table SPM.1). This evidence for human influence has grown since AR4. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. {10.3–10.6, 10.9}
Report at SPM-12 (original emphasis).