IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

7.4 Key future impacts and vulnerabilities

The ability to project how climate change may affect industry, settlement and society is limited by uncertainties about climate change itself at a relatively fine-grained geographical and sectoral scale and also by uncertainties about trends in human systems over the next century regardless of climate change (Chapter 2). In some cases, uncertainties about socio-economic factors such as technological and institutional change over many decades undermine the feasibility of comparing future prospects involving considerable climate change with prospects involving relatively little climate change. Typically, therefore, research often focuses on vulnerabilities to impacts of climate change (defined as the degree to which a system, subsystem or system component is likely to experience harm due to exposure to a perturbation or source of stress (Turner et al., 2003a; also see Clark et al., 2000) rather than on projections of impacts of change on evolving socio-economic systems, especially in the longer run.

Furthermore, climate change will not often be a primary factor in changes for industry, settlement and society. Instead, it will have an impact by modifying other more significant aspects of ongoing socio-economic changes. This may have either an exacerbating or an ameliorating effect in influencing overall vulnerabilities to multi-causal change. It is especially difficult to associate levels of climate-change impacts or their costs with a specified number of degrees of mean global warming or with a particular time horizon such as 2050 or 2080, when so many of the main drivers of impacts and costs are not directly climate-related, even though they may be climate-associated, and when impacts are often highly localised. Some projections have been made for particular sectors or areas and they are cited in appropriate sections below; but in general they should be considered with caution, especially for longer-range futures.