1.2.1.2 Non-climate drivers of change

Non-climate drivers, such as land use, land degradation, urbanisation and pollution, affect systems directly and indirectly through their effects on climate (Table 1.1). These drivers can operate either independently or in association with one another (Lepers et al., 2004). Complex feedbacks and interactions occur on all scales from local to global.

The socio-economic processes that drive land-use change include population growth, economic development, trade and migration; these processes can be observed and measured at global, regional and local scales (Goklany, 1996). Satellite observations demonstrate that land-use change, including that associated with the current rapid economic development in Asia and Latin America, is proceeding at an unprecedented rate (Rindfuss et al., 2004). Besides influencing albedo and evaporation, land-use changes hamper range-shift responses of species to climate change, leading to an extra loss of biodiversity (Opdam and Wascher, 2004). Additionally, land-use changes have been linked to changes in air quality and pollution that affect the greenhouse process itself (Pielke et al., 2002; Kalnay and Cai, 2003). Land-use and land-cover change can also strongly magnify the effects of extreme climate events, e.g., heat mortality, injuries/fatalities from storms, and ecologically mediated infectious diseases (Patz et al., 2005). Intensification of land use, as well as the extent of land-use change, is also affecting the functioning of ecosystems, and hence emissions of greenhouse gases from soils, such as CO2 and methane.

There are also a large number of socio-economic factors that can influence, obscure or enhance the observed impacts of climate change and that must be taken into account when seeking a climate signal or explaining observations of impacts and even adaptations. For example, the noted effects of sea-level rise and extreme events are much greater when they occur in regions with large populations, inadequate infrastructure, or high property prices (Pielke et al., 2003). The observed impacts of climate change on agriculture are largely determined by the ability of producers to access or afford irrigation, alternate crop varieties, markets, insurance, fertilisers and agricultural extension, or to abandon agriculture for alternate livelihoods (Eakin, 2000). Demography (e.g., the elderly and the very young), poverty (e.g., malnutrition and poor living conditions), preventive technologies (e.g., pest control and immunisation), and healthcare institutions influence the impacts of climate change on humans.