The Second Assessment Report (SAR) of the Intergovernmental Panel on Climate Change (IPCC) was published in 1995 and is an assessment of available scientific and socio-economic information on climate change. The IPCC was established by the United Nations Environment Programme (UNEP) and the UN's World Meteorological Organization (WMO).
It was followed by the Third Assessment Report (TAR) in 2001.
Working groups
The IPCC's organisation is currently structured as three working groups (WG) and a task force [1]:
- Working Group I: Scientific aspects of climate [2]
- Working Group II: Vulnerability, consequences, and options [3]
- Working Group III: Limitation and mitigation options [4]
- Task Force: National Greenhouse Gas Inventories Programme [5]
Second Assessment Report (SAR)
The SAR consists of four parts:[1]
- the IPCC Second Assessment Synthesis of Scientific-Technical Information Relevant to Interpreting Article 2 of the UN Framework Convention on Climate Change.
- the Report of Working Group I - the Science of Climate Change, with a Summary for Policymakers (SPM); (JT Houghton, LG Meira Filho, BA Callender, N Harris, A Kattenberg and K Maskell (Eds); Cambridge University Press, UK. pp 572).
- the Report of Working Group II - Scientific-Technical Analyses of Impacts, Adaptations and Mitigation of Climate Change, with SPM; (R.T.Watson, M.C.Zinyowera, R.H.Moss (Eds); Cambridge University Press, UK. pp 878).
- the Report of Working Group III - the Economic and Social Dimensions of Climate Change, with SPM; (J.P.Bruce, H.Lee, E.F.Haites (Eds); Cambridge University Press, UK. pp 448).
Conclusions
The major conclusions of Working Group I, which deals with the scientific aspects of climate [6], were:
- Greenhouse gas concentrations have continued to increase
- Anthropogenic aerosols tend to produce negative radiative forcings
- Climate has changed over the past century
- The balance of evidence suggests a discernible human influence on global climate
- Climate is expected to continue to change in the future
- There are still many uncertainties
Its eighth chapter noted "these results indicate that the observed trend in global mean temperature over the past 100 years is unlikely to be entirely natural in origin. More importantly, there is evidence of an emerging pattern of climate response to forcings by greenhouse gases and sulphate aerosols in the observed climate record. Taken together, these results point towards a human influence on global climate." [ch 8, summary, p 412].
Analysis
The Third Assessment Report of IPCC analysed the Working Group I's part of the Second Assessment Report as follows:[7]
- "The report underscored that greenhouse gas abundances continued to increase in the atmosphere and that very substantial cuts in emissions would be required for stabilisation of greenhouse gas concentrations in the atmosphere (which is the ultimate goal of Article 2 of the Framework Convention on Climate Change). Further, the general increase in global temperature continued, with recent years being the warmest since at least 1860. The ability of climate models to simulate observed events and trends had improved, particularly with the inclusion of sulphate aerosols and stratospheric ozone as radiative forcing agents in climate models. Utilising this simulative capability to compare to the observed patterns of regional temperature changes, the report concluded that the ability to quantify the human influence on global climate was limited. The limitations arose because the expected signal was still emerging from the noise of natural variability and because of uncertainties in other key factors. Nevertheless, the report also concluded that "the balance of evidence suggests a discernible human influence on global climate". Lastly, based on a range of scenarios of future greenhouse gas abundances, a set of responses of the climate system was simulated."
