Climate Change 1995 IPCC Second Assessment Report

An overview of the complete reports of the Intergovernmental Panel on Climate Change (IPCC) to be published this spring by Cambridge University Press was presented at the AAAS meeting in Baltimore, MD in February 1996. Of special interest to ecologists will be the results of Working Group II: Scientific Analyses of Impacts, Adaptations, and Mitigation of Climate Change. Working Group I directly analyzed greenhouse gases, climate and climate change.

The Working Group II report includes chapters on forests, rangelands, deserts, the cryosphere, mountain regions, hydrology and freshwater ecology, non-coastal wetlands, coastal zones and small islands, and oceans; as well as on land degradation and desertification, human settlement, agriculture, forest products, water resources management, human population health, and more. Working Group III treats economic and social dimensions.

The major points presented on the climate system and greenhouse gases were that greenhouse gases continue to increase, anthropogenic aerosols negatively influence radiative forcing and counter greenhouse warming in some places, climate has warmed in the last century, the influence of humans on the climate appears to be discernible, climate change is expected to continue, and there are many uncertainties.

Among the uncertainties: Future unexpected, large and rapid climate system changes (as have occurred in the past) are, by their nature difficult to predict. This implies that future climate changes may also involve "surprises." In particular, these arise from the non-linear nature of the climate system. When rapidly forced, nonlinear systems are especially subject to unexpected behavior. Progress can be made by investigating nonlinear processes and sub-components of the climatic system. Examples of such non-linear behavior include rapid circulation changes in the North Atlantic and feedbacks associated with terrestrial ecosystem changes.

Summaries of the IPCC Second Assessment are available on the UNEP web site at: http.//www.unep.ch/ipcc/ipcc95.html