Climate change: an Australian guide to the science and potential impacts

This guide sets out the main facts and uncertainties regarding climate change, and helps provide Australians with policy-relevant, but not policy-prescriptive, advice and source material. It is largely based on, and consistent with, the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC TAR) published in 2001. However, this guide has been substantially updated with relevant summaries of the latest international and Australian observations, scientific developments, and studies regarding the impacts of, and adaptation to climate change in Australia. While much progress in understanding the climate change issue has been made, uncertainties continue to exist about aspects of the climate change science, and regarding societal developments that will affect the extent of future climate change and societal vulnerability. Some impacts of climate change are now inevitable. However, more certainty and understanding is needed to guide decision-makers towards the most effective and cost-efficient means to adapt to climate changes in the near-term (next decade), and to avoid unacceptably large climate changes in the longer term (multi-decades to centuries) through emissions reductions measures. The high probability of at least some global warming, given the inertia in the climate and socioeconomic systems, means that some adaptation will be necessary. This will be most efficient if the location- and activity-specific nature of the likely impacts is taken into account. Considerable uncertainties about location-specific impacts can be further reduced by targeted research, while caseby- case assessments of adaptation strategies will be needed for many particular sectors and locations. Any emission reductions will progressively reduce the likelihood of impacts at the high end of the existing large range of emissions scenarios, and thus help to avoid the potentially most damaging climate change possibilities. Thus, in order to establish minimum objectives for emissions reductions, attention needs to be given to the more extreme possibilities to which adaptation may not be possible. These will determine critical greenhouse gas concentration thresholds that must be avoided if the objective of the United Nations Framework Convention on Climate Change is to be achieved. Increased research is needed to quantify the probability and global and local consequences of these high impact scenarios.