Australia’s climate is one of the most varied in the world, ranging from the wet tropical regions in the north to arid conditions in the centre, and temperate and humid climates in the coastal south. The country’s position within the “horse latitudes” contributes to its dry conditions, making it the driest inhabited continent with an average annual rainfall of only 470 millimetres (19 inches). Around 70% of the country is arid or semi-arid, and approximately 18% is desert. This variation in climate is influenced by systems like the El Niño–Southern Oscillation, the Indian Ocean Dipole, and the Southern Annular Mode, all of which contribute to the frequency of droughts, flooding, cyclones, and irregular rainfall patterns. Tropical cyclones and rain depressions are common in the north, while the southern regions experience more rainfall during the winter months. Bushfires are a constant risk in southern Australia, particularly during the summer months.

Recent climate change has dramatically impacted the continent. Since 1910, Australia’s temperatures have risen by 1.5°C, leading to more extreme heatwaves and increased heavy rainfall events. Since 1970, rainfall in southern Australia has decreased, while northern areas have seen an increase in precipitation. The country has also experienced a reduction in tropical cyclones since 1982, along with diminishing alpine snow since the 1950s. As global temperatures continue to rise, sea levels around Australia are also increasing, while the surrounding oceans are becoming more acidic.

Australia’s biodiversity, shaped by its long isolation, is unique and exceptionally rich. The continent is home to a vast number of endemic species, with 94% of amphibians, 93% of reptiles, and 69% of mammals found nowhere else in the world. Australia’s ecosystems are varied, covering 89 regions and 419 subregions in the Australian bioregion framework. However, only about 10% of the world’s known plant species are native to Australia, and many have adapted to the harsh climate, poor soils, and frequent bushfires. Species such as the iconic koala and honey possum have evolved to feed on nectar and pollen, while marsupials like the kangaroo and wallaby have developed lower energy requirements to thrive in the nutrient-poor environment.

Despite its rich biodiversity, Australia has experienced significant losses over the past two centuries, particularly among its mammal species. It has lost more mammal species than any other continent, with 100 species now extinct or extinct in the wild. In June 2021, over 1,000 species of plants and animals were listed as endangered or critically endangered due to threats like climate change, introduced predators, and habitat loss. The Australian government has responded with the Environment Protection and Biodiversity Conservation Act of 1999, alongside the National Reserve System, which now protects over 22% of the country’s land mass. Australia’s Strategy for Nature 2024–2030 aims to reverse the decline in biodiversity by 2030, in line with international conservation agreements.

Australia’s climate and biodiversity face immense challenges as the country contends with the effects of climate change. With a significant portion of its unique species threatened, the government is prioritizing conservation efforts to protect the continent’s natural heritage and biodiversity for future generations.