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

11.4.12 Synthesis

Climate change adds new dimensions to the challenges already facing communities, businesses, governments and individuals. Assessment of the information given in this section leads to the conclusion that climate change is likely to give rise to six key risks in specific sectors (Table 11.7): natural systems, water security, coastal communities, agriculture and forestry, major infrastructure and health. Some extreme events can trigger multiple and simultaneous impacts across systems, e.g., heatwaves leading to heat-related deaths, fires, smoke pollution, respiratory illness, blackouts, and buckling of railways. There are also four key benefits for particular sectors: (i) in New Zealand, initial benefits to agriculture and forestry are projected in western and southern areas and close to major rivers due to a longer growing season, less frost and increased rainfall; (ii) reduced energy demand is very likely in winter; (iii) tourism is likely to directly benefit from drier and warmer weather in some areas; and (iv) flows in New Zealand’s larger mountain-fed rivers are likely to increase, benefiting hydroelectricity generation and irrigation supply. Adaptation can alleviate or delay vulnerability in some sectors, as well as allowing benefits to accrue more rapidly (see Section 11.5).

Table 11.7. Six key risks in Australia (Aus) and New Zealand (NZ) (assuming no new adaptation). Underlying climate projections (see Section 11.3) include higher temperatures, sea-level rise, heavier rainfall, greater fire risk, less snow cover, reduced runoff over southern and eastern Australia and in the smaller lowland rivers of eastern New Zealand, more intense tropical cyclones and larger storm surges.

System Impacts Identified hotspots 
Natural systems Damage to coral reefs, coasts, rainforests, wetlands and alpine areas. Increased disturbance, loss of biodiversity including possible extinctions, changed species ranges and interactions, loss of ecosystem services (e.g., for tourism and water). Potentially catastrophic for some systems (e.g., reefs may be dominated by macroalgae by 2050, extinctions of endemic vertebrates in Queensland Wet Tropics). Shrinking glaciers create slope instability. Aus: Great Barrier Reef, Kakadu, east Queensland, alpine zones, Murray-Darling Basin (MDB) and south-western Aus; NZ: Southern Alps and their National Parks, eastern lowlands  
Water security Reduction in water supply for irrigation, cities, industry and riverine environment in those areas where streamflow declines, e.g., in the Murray-Darling Basin, annual mean flow may drop 10 to 25% by 2050 and 16 to 48% by 2100. Southern and eastern Aus; Northland and parts of eastern lowlands of NZ 
Coastal communities Greater coastal inundation and erosion, especially in regions exposed to cyclones and storm surges. Coastal development is exacerbating the climate risks.  Tropical and south-east Queensland (Aus) and from Bay of Plenty to Northland in NZ  
Agriculture and forestry Reduced crop, pastoral and rangeland production over much of southern and eastern Australia and parts of eastern New Zealand. Reduced grain and grape quality. A southward shift of pests and disease vectors. Increased fire risk for forests. Southern and eastern Aus and eastern NZ 
Major infrastructure  Design criteria for extreme climatic events, floods and storm surges very likely to be exceeded more frequently. Increased damage likely for buildings, transport structures, telecommunications, energy services and water services.  Large cities, floodplains of major rivers, coastal communities, north-eastern parts of both countries 
Health By 2050, 3,200 to 5200 more heat-related deaths/yr, and 0.6 to 1.4 million more people exposed to dengue fever.  Large cities of both countries