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.