The Intergovernmental Panel on Climate Change (IPCC) is a scientific body established at the request of member governments in 1988 by the United Nations Environment Programme (UNEP) and the United Nations’ World Meteorological Organisation (WMO) to, among other provisions, assess scientific, technical and socio-economic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation.
Chaired by Indian Rajendra Pachauri, the IPCC publishes special reports on topics relevant to the implementation of the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty that acknowledges the possibility of harmful climate change. Implementation of the UNFCCC led eventually to the emergence of the Kyoto Protocol. The IPCC, whose membership is open to all members of the WMO and UNEP, bases its assessment mainly on peer reviewed and published scientific literature.
The IPCC provides an internationally-accepted authority on climate change, producing reports which have the agreement of all the leading climate scientists and the consensus of every one of the participating governments. It has successfully provided authoritative policy advice with far-reaching implications for economics and lifestyles.
The body has so far produced four different Assessment Reports and the fifth is in the works and will be finalised in phases from September 2013 to October 2014.
The Fifth Assessment Report (AR5) comprises three Working Group contributions and a Synthesis Report. The Working Group I contribution on The Physical Science Basis is scheduled to be released on 27 September 2013 after its approval and acceptance at a plenary session to be held on 23-26 September 2013 in Stockholm, Sweden.
The Working Group II contribution on Impacts, Adaptation and Vulnerability, is scheduled to be released on or around 30 March 2014 after its approval and acceptance at a plenary session to be held on 25-29 March 2014 in Yokohama, Japan.
The Working Group III contribution on Mitigation of Climate Change is scheduled to be released on 12 April 2014 after its approval and acceptance at a plenary session to be held on 7-11 April 2013 in Germany. The Synthesis Report which synthesises and integrates materials contained within the Working Group contributions is scheduled to be released on or around 1 November 2014 after its approval and acceptance at a plenary session to be held on 27-31 October 2014.
Completed in 1990, the First Assessment Report (AR1) was issued in three main sections, corresponding to the three Working Groups of scientists that the IPCC had established. The report actually served as basis for the UNFCCC.
The sections were: Working Group I (Scientific Assessment of Climate Change), Working Group II (Impacts Assessment of Climate Change) and Working Group III (The IPCC Response Strategies). Among others, the report confirmed the natural greenhouse effect; stated that carbon dioxide (CO2) has been responsible for over half the enhanced greenhouse effect; and submitted that global mean surface air temperature has increased by 0.3 to 0.6oC over the last 100 years.
Published in 1996, the Second Assessment Report (AR2) was titled Climate Change 1995 and consists of reports from Working Group I (The Science of Climate Change),Working Group II (Impacts, Adaptations and Mitigation of Climate Change: Scientific-Technical Analyses) and Working Group III (Economic and Social Dimensions of Climate Change).
The reports were prepared by over 2,000 experts, and contain the factual basis of the issue of climate change, gleaned from available expert literature and further carefully reviewed by experts and governments. While Working Group I stated that carbon dioxide remains the most important contributor to anthropogenic forcing of climate change, Working Group II assessed whether the range of plausible impacts of global warming constitutes dangerous anthropogenic interference with the climate system, while Working Group III provided information to help countries “take decisions they believe are most appropriate for their specific circumstances”.
Key conclusions of the Third Assessment Report (AR3), Climate Change 2001, state that emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate; that there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities; that human influences will continue to change atmospheric composition throughout the 21st century; and that global average temperature and sea level are projected to rise.
The Fourth Assessment Report (AR4) of 2007 is considered the largest and most detailed summary of the climate change situation ever undertaken. It was produced by thousands of authors, editors, and reviewers from dozens of countries, citing over 6,000 peer-reviewed scientific studies. It will however be superseded by the AR5 expected next year.
The headline findings of the report were: that “warming of the climate system is unequivocal”, and that “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas (GHG) concentrations.”