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

11.2.3 Natural systems: sensitivity/vulnerability to climate and weather

Some species and natural systems in Australia and New Zealand are already showing evidence of recent climate-associated change (Table 11.1). In many cases, the relative contributions of other factors such as changes in fire regimes and land use are not well understood.

Table 11.1. Examples of observed changes in species and natural systems linked to changing climate in Australia, New Zealand and their sub-Antarctic islands.

Taxa or system Observed change References 
Rainforest and woodland ecotones Expansion of rainforest at the expense of eucalypt forest and grassland in Northern Territory, Queensland and New South Wales, linked to changes in rainfall and fire regimes.  Bowman et al., 2001; Hughes, 2003 
Sub-alpine vegetation Encroachment by snow gums into sub-alpine grasslands at higher elevations. Wearne and Morgan, 2001 
Freshwater swamps and floodplains Saltwater intrusion into freshwater swamps since the 1950s in Northern Territory accelerating since the 1980s, possibly associated with sea level and precipitation changes. Winn et al., 2006 
Coral reefs Eight mass bleaching events on the Great Barrier Reef since 1979, triggered by unusually high sea surface temperatures; no serious events known prior to 1979 (see Section 11.6). Most widespread events appear to have occurred in 1998 and 2002, affecting up to 50% of reefs within the Great Barrier Reef Marine Park.  Hoegh-Guldberg, 1999; Done et al., 2003; Berkelmans et al., 2004 
Birds Earlier arrival of migratory birds; range shifts and expansions for several species; high sea surface temperatures associated with reduced reproduction in wedge-tailed shearwaters. Smithers et al., 2003; Chambers, 2005; Chambers et al., 2005; Beaumont et al., 2006 
Mammals  Increased penetration of feral mammals into alpine and high sub-alpine areas and prolonged winter presence of macropods.  Green and Pickering, 2002 
Insects Change in genetic constitution of Drosophila, equivalent to a 4° latitude shift (about 400 km). Umina et al., 2005 
New Zealand     
Birds Earlier egg laying in the welcome swallow.  Evans et al., 2003 
Southern beech Seed production increase in Nothofagus (1973 to 2002) along elevational gradient related to warming during flower development. Richardson et al., 2005 
Fish Westward shift of Chilean jack mackerel in the Pacific and subsequent invasion into New Zealand waters in the mid-1980s associated with increasing El Niño frequency. Taylor, 2002 
Glaciers Ice volume decreased from about 100 km3 to 53 km3 over the past century. Loss of at least one-quarter of glacier mass since 1950. Mass balance of Franz Josef glacier decreased 0.02 m/yr from 1894 to 2005. Chinn, 2001; Clare et al., 2002; Anderson, 2004  
Sub-Antarctic Islands     
Birds Population increases in black-browed albatross and king penguin on Heard Island; population declines on Campbell Island of rockhopper penguins, grey-headed albatross and black-browed albatross related to ocean warming and changed fishing practices. Waugh et al., 1999; Woehler et al., 2002; Weimerskirch et al., 2003 
Vertebrates Population increases in fur seals on Heard Island and elephant seals on Campbell Island, linked to changes in food supply, warming and oceanic circulation; rats moving into upland herb-fields and breeding more often on Macquarie Island. Budd, 2000; Weimerskirch et al., 2003; Frenot et al., 2005 
Plant communities Plant colonisation of areas exposed by glacial retreat on Heard Island; decline in area of sphagnum moss since 1992 on Macquarie Island associated with drying trend. Whinam and Copson, 2006