Introduction Surface air temperatures have increased approximately 0.6°C globally since the mid-nineteenth century and the magnitude of this warming is the largest of any century in the last 1000 years (Intergovernmental Panel on Climate Change (IPCC) 2001b). The 1990s were the warmest decade, and 1998 the warmest year, on record, both globally and in Australia. There is widespread acceptance, in both the scientific and general communities, that this warming trend, together with changes in sea level and rainfall, is now dis- cernible above natural decadal- and century-scale variabil- ity and that anthropogenic production of greenhouse gases is largely responsible (IPCC 2001b). Evidence is also mounting that anomalously high temperatures in the twentieth century have been associated with changes in many physical and biological systems, including acceler- ated glacial retreat, thawing of permafrost, lengthening of growing seasons, and alterations in the phenology of flower- ing, breeding and migration of many species (Hughes 2000; Walther et al. 2002; Parmesan and Yohe 2003; Root et al. 2003). Surprisingly, a recent IPCC report (IPCC 2001a) lists no avian studies associated with regional temperature change for the Australian region. The report lists changes in 388 bird species that were associated with regional temperature change in areas outside Australia. The aims of this review are to: (1) briefly summarise recent climatic trends apparent both globally and in Australia; (2) describe how these trends have been associated with changes in the distribution, abundance and phenology of birds in Australia and elsewhere; and (3) highlight some directions for future study and monitoring to improve pre- dictions as to how climate change may affect birds, and therefore improve long-term conservation efforts for the Australian avifauna. The review encompasses birds both from continental Australia and those that occupy Australian territories, including Antarctica, at some stage in their life cycle. Climate trends: past and future Consistent with global trends, Australia’s continental average temperature increased 0.7°C from 1910 to 1999, with most of the increase recorded since 1950 (Collins et al. 2000; Nicholls 2003); 1998 was also Australia’s warmest year, and 2002 and 2003 the fifth and sixth warmest (National Climate Centre (NCC) 2004). The 1990s was the warmest decade and the 1980s the second warmest on record (Collins 2000). Recent warming has been greatest in winter and spring (Hulme and Sheard 1999). Night-time temper- atures have increased more than daytime temperatures (Suppiah et al. 2001; Lenten and Moosa 2003), consistent with global trends (Easterling et al. 1997). Occurrences of extreme warm events have generally increased over the period 1957–96, while the numbers of extreme cool events have decreased (Plummer et al. 1999; Collins et al. 2000). Warmer temperatures have apparently reduced the frequency and duration of frosts (Stone et al. 1996) and may have contributed to the severity of the 2002 drought (Karoly et al. 2003; Nicholls 2004). Sea-surface temperatures (SST) in many tropical regions have increased almost 1°C over the Emu, 2005, 105, 1–20 10.1071/MU04033 0158-4197/05/010001 © Royal Australasian Ornithologists Union 2005 Lynda E. Chambers A , Lesley Hughes B and Michael A. Weston C A Bureau of Meteorology Research Centre, GPO Box 1289K, Melbourne, Vic. 3001, Australia. Email: L.Chambers@bom.gov.au B Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia. Email: lhughes@rna.bio.mq.edu.au C Research and Conservation Department, Birds Australia, 415 Riversdale Road, Hawthorn East, Vic. 3123, Australia. Email: m.weston@birdsaustralia.com.au Abstract. Relative to the northern hemisphere, little is known about the effect of climate change on southern hemisphere birds, although the impact could be significant. Here we review the effects of climate change on birds that have been documented or predicted, with particular reference to Australian species. Potential impacts include changes in geographic range, movement patterns, morphology, physiology, abundance, phenology and community composition. The evidence suggests that these changes are already happening, both overseas and in Australia, but more research is needed to determine the extent of these impacts and how to conserve birds in the face of climate change. Management options include promoting adaptation and resilience, intensive management of sensitive species, and improved planning for mitigation techniques and monitoring. Climate change and its impact on Australia’s avifauna www.publish.csiro.au/journals/emu CSIRO PUBLISHING