11.2.4 Sensitivity/vulnerability to other stresses
Human and natural systems are sensitive to a variety of stresses independent of those produced by climate change. Growing populations and energy demands have placed stress on energy supply infrastructure. In Australia, energy consumption has increased 2.5%/yr over the past 20 years (PB Associates, 2007). Increases in water demand have placed stress on supply capacity for irrigation, cities, industry and environmental flows. Increased water demand in New Zealand has been due to agricultural intensification (Woods and Howard-Williams, 2004) and has seen the irrigated area of New Zealand increase by around 55% each decade since the 1960s (Lincoln Environmental, 2000). Per capita daily water consumption is 180-300 litres in New Zealand and 270 litres for Australia (Robb and Bright, 2004). In Australia, dryland salinity, alteration of river flows, over-allocation and inefficient use of water resources, land clearing, intensification of agriculture, and fragmentation of ecosystems still represent major stresses (SOE, 2001; Cullen, 2002). From 1985 to 1996, Australian water demand increased by 65% (NLWRA, 2001). Invasive plant and animal species pose significant environmental problems in both countries, particularly for agriculture and forestry (MfE, 2001; SOE, 2001); for example, Cryptostegia grandiflora (Kriticos et al., 2003a, b).