As the climate warms Australia's ecosystems are experiencing stresses with sometimes catastrophic consequences, such as mass deaths of flying foxes in Queensland during heat waves and severe bleaching of the Great Barrier Reef. These impacts will become more severe as global temperatures rise.
The Paris Agreement of 2015 aims to limit global warming to 2oC above a pre-industrial baseline, with a more ambitious target of 1.5oC preferred. If we are to stabilize the world’s climate at 1.5oC we will need to do so after first overshooting the limit and then bringing global temperature back down by actually removing carbon dioxide from the atmosphere.
It is estimated that by around the late 2020s to early 2030s we will be hitting the 1.5oC mark and we will likely reach 2oC a couple of decades later. As well as increasing greenhouse gas concentrations, climate phenomena such as decade-to-decade variations in the Pacific Ocean can speed up or slow down the rise in global temperatures. The Pacific is showing early signs of shifting into a warm phase, which could accelerate global temperatures to the 1.5°C level and beyond.
The consequences of going beyond 1.5oC for the Great Barrier Reef could be disastrous. At 1.5oC global warming, temperatures in the Coral Sea like those observed in early 2016 could occur in two of every three years. In a 2oC world, the 2016 event would actually be unusually cool.
On land we will see hot summers like the record heat of the “Angry Summer” of 2012–13 occurring more frequently at 2oC than at 1.5oC. Also, hot and dry conditions in the southeast of Australia, such as we experienced during the Millennium Drought, will likely become more common.
There are clear benefits to Australia’s ecosystems if we meet the Paris target of limiting global warming to 1.5oC. The question is: will we take sufficient action to reduce our greenhouse gas emissions to do so?