At a glance
The climate of Antarctica is changing. Compared with conditions prevailing in the 1950s, parts of West Antarctica—particularly the Antarctic Peninsula region—have warmed. In East Antarctica, where Australia operates, temperatures have also increased, but to a lesser extent. Across Antarctica, many environmental observations show modest rates of change and large year-to-year variability, which limits the ability to ascribe significance to trends in most cases. However, changes have been observed, including increased maximum sea ice extent, strengthened westerly winds, altered ocean properties and thinning of some ice shelves, in addition to specific seasonal and regional trends in temperatures. These environmental changes—and our new understanding of the physical environment, bedrock, ice thickness and ocean–ice boundaries—suggest that further change is likely, with associated impacts on marine and terrestrial ecosystems. In some regions, changes mirroring those already under way in West Antarctica are possible, with potentially profound global impacts.
Globally, extreme weather events such as heatwaves, storm surges and increased precipitation are expected to increase in frequency and intensity as the planet warms. In certain regions at the periphery of Antarctica, rain is now occasionally falling where historically it only ever used to snow. These events are changing the Antarctic environment and may affect the biodiversity that has developed under a specific moisture regime. Climate change is also driving ocean acidification, which will affect many Antarctic marine species, including crucial species at the base of the food web.
Human activities are still increasing; new stations are being constructed, often in rare ice-free areas. Tourism is a major activity around the Antarctic Peninsula. Disturbance of habitat and wildlife, introduction of invasive plants and other alien organisms, and pollution are all risks linked to human presence on the continent. Marine debris, particularly plastics, is an increasing pressure on Antarctic species, causing mortality and morbidity through entanglement and ingestion. The debris comes both from human presence on the continent and human pollution throughout the rest of the planet, which makes its way to Antarctic regions. Worldwide demand for fishery products means that fishing and other legal or illegal extraction of resources are pressures on the Antarctic environment and its species.
Subantarctic islands are changing rapidly as rainfall patterns are changing, and glaciers at Heard Island are retreating and thinning. Although eradication efforts have successfully reduced the impact of introduced species on some islands, the changing climate is likely to pave the way for more invaders.
This section presents information on matters that affect the Antarctic environment and describes the current state of the environment. The focus is on the AAT, because this is where Australia’s activities are centred, although certain trends in the environment may relate to East Antarctica in general, or Antarctica as a whole. Also discussed are Australia’s subantarctic islands—Macquarie Island, and Heard Island and McDonald Islands—and the Southern Ocean.
Discussing every aspect of the Antarctic environment comprehensively is beyond the scope of this section. Instead, this section reports on several selected indicators, some of which have long-term (more than 1 decade) data that offer the best representation of current change in high-priority areas. The discussion identifies and considers environmental variables that are currently subject to pressures that are likely to be influential in the foreseeable future. We summarise indicators discussed in recently published scientific literature, and offer information about operational indicators that are relevant to running the Australian Antarctic Program. Although only a limited number of sites are monitored regularly in the AAT, some results are representative of other areas in East Antarctica with similar ecological characteristics. Where appropriate, comparisons are made with events occurring in West Antarctica, where environmental change is proceeding at a faster rate than in the eastern part of the continent.