The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess scientific information on climate change, evaluate its environmental and socio-economic impacts, and formulate response strategies. The IPCC's assessments, including the Fourth Assessment Report (AR4), are the most comprehensive and up-to-date reports on climate change, serving as standard references for policymakers, scientists, and industry. The Synthesis Report of AR4, "Climate Change 2007," summarizes findings from three working groups and addresses key issues for policymakers, confirming that climate change is occurring due to human activities, illustrating its impacts, and describing adaptation and mitigation options. The Synthesis Report is based on assessments by the three working groups, which include the Physical Science Basis, Impacts, Adaptation and Vulnerability, and Mitigation of Climate Change. It integrates scientific, technical, and socio-economic information on climate change, providing a synthesis for policymakers. The report highlights observed climate changes, their causes, projected future changes, and their impacts, as well as adaptation and mitigation options. It also discusses long-term perspectives, scientific and socio-economic aspects relevant to adaptation and mitigation, and robust findings and key uncertainties. The Synthesis Report was prepared by a team of experts, including the Core Writing Team and the Technical Support Unit, and was adopted at the IPCC's Twenty Seventh Session in Valencia, Spain. It is part of the "Climate Change 2007" series, which includes the three working group reports and other IPCC publications. The report is intended to assist governments and other decision-makers in formulating and implementing responses to climate change. It is a self-contained document that needs to be viewed in the context of the other volumes of "Climate Change 2007." The report includes a Summary for Policymakers, a longer report, and annexes with user guides, glossaries, and lists of authors and reviewers. The Synthesis Report is a major achievement involving over 500 lead authors and 2000 expert reviewers, reflecting the collaboration of a wide scientific community. It is a key reference for understanding the current state of climate change and its potential impacts.The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess scientific information on climate change, evaluate its environmental and socio-economic impacts, and formulate response strategies. The IPCC's assessments, including the Fourth Assessment Report (AR4), are the most comprehensive and up-to-date reports on climate change, serving as standard references for policymakers, scientists, and industry. The Synthesis Report of AR4, "Climate Change 2007," summarizes findings from three working groups and addresses key issues for policymakers, confirming that climate change is occurring due to human activities, illustrating its impacts, and describing adaptation and mitigation options. The Synthesis Report is based on assessments by the three working groups, which include the Physical Science Basis, Impacts, Adaptation and Vulnerability, and Mitigation of Climate Change. It integrates scientific, technical, and socio-economic information on climate change, providing a synthesis for policymakers. The report highlights observed climate changes, their causes, projected future changes, and their impacts, as well as adaptation and mitigation options. It also discusses long-term perspectives, scientific and socio-economic aspects relevant to adaptation and mitigation, and robust findings and key uncertainties. The Synthesis Report was prepared by a team of experts, including the Core Writing Team and the Technical Support Unit, and was adopted at the IPCC's Twenty Seventh Session in Valencia, Spain. It is part of the "Climate Change 2007" series, which includes the three working group reports and other IPCC publications. The report is intended to assist governments and other decision-makers in formulating and implementing responses to climate change. It is a self-contained document that needs to be viewed in the context of the other volumes of "Climate Change 2007." The report includes a Summary for Policymakers, a longer report, and annexes with user guides, glossaries, and lists of authors and reviewers. The Synthesis Report is a major achievement involving over 500 lead authors and 2000 expert reviewers, reflecting the collaboration of a wide scientific community. It is a key reference for understanding the current state of climate change and its potential impacts.