In December 2019, the average temperature across Australia was about 2°C above what would be expected for the present-day, which is another 1.5°C above temperatures that were normal for December before humans started warming the climate. These extreme temperatures have contributed to the catastrophic bushfires which have devastated large areas.
But what may be considered ‘normal’ is constantly changing.
In a world which has warmed by 3°C – roughly the current global trajectory – what was extreme will be entirely normal.
The extreme temperatures experienced in Australia are therefore a glimpse of the future. Similar unusual weather patterns to those experienced in December in that future world would cause extreme temperatures that are unimaginable now.
This graphic uses observations of average December temperature for Australia and regresses this against a smoothed global annual average temperature. Land areas warm faster than ocean areas, and so it is found that December temperatures in Australia are warming 1.4x faster than the global annual average. Assuming the same relationship holds in future allows the estimates of what Australian temperatures will be normal for different levels of total global warming.