A/HRC/10/61 page 4 I. CLIMATE CHANGE: AN OVERVIEW Global warming and its causes 5. The United Nations Framework Convention on Climate Change, which has near universal membership, provides the common international framework to address the causes and consequences of climate change, also referred to as “global warming”. The Convention defines climate change as “a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”.5 6. The Intergovernmental Panel on Climate Change (IPCC) has greatly contributed to improving understanding about and raising awareness of climate change risks.6 Since the publication of its First Assessment Report (IPCC AR1) in 1990, climate science has rapidly evolved, enabling the IPCC to make increasingly definitive statements about the reality, causes and consequences of climate change. Its Fourth Assessment Report (IPCC AR4), issued in 2007, presents a clear scientific consensus that global warming “is unequivocal” and that, with more than 90 per cent certainty, most of the warming observed over the past 50 years is caused by manmade greenhouse gas emissions.7 Current levels of greenhouse gas concentrations far exceed pre-industrial levels as recorded in polar ice cores dating back 650,000 years, and the predominant source of this increase is the combustion of fossil fuels.8 7. The IPCC AR4 presents the current scientific consensus on climate change. It is based on the contributions of three working groups focusing on: the physical science basis (Working Group I); impacts, adaptation and vulnerability (Working Group II); and mitigation of climate change (Working Group III). The Synthesis Report and Summaries for Policymakers have been adopted and approved by member States at an IPCC plenary session. The findings provide the main scientific resource for this study in exploring the relationship between climate change and human rights. 5 United Nations Framework Convention on Climate Change (UNFCCC), art. 1, para. 2. The Intergovernmental Panel on Climate Change (IPCC) uses a similar definition, the main difference being that IPCC covers all aspects of climate change and does not make a distinction between climate change attributable to human activity and climate change and variability attributable to natural causes. 6 IPCC was set up jointly by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) in 1988 to provide authoritative assessments, based on the best available scientific literature, on climate change causes, impacts and possible response strategies. 7 Climate Change 2007 - Synthesis Report, adopted at IPCC Plenary XXVII, Valencia, Spain, 12-17 November 2007 (IPCC AR4 Synthesis Report), p. 72. 8 See IPCC AR4 Working Group I (WGI) Report, pp. 23-25.