To reach such targets Professor Steffen said the government would need to immediately halt the expansion of coal and gas and plan to support affected communities as fossil fuels were phased out. Secondly, Australia would have to reach almost 100 per cent renewables in its energy system by 2030.
The report finds “multiple lines of evidence” that the world will break through 1.5 degrees: the increasing pace at which the world has been warming since 2016; new scientific understanding of the climate system’s sensitivity; and the increasing rate of sea levels rising. There is also an analysis of global greenhouse gas emissions which are now in line with the highest of four scenarios considered in the fifth assessment of the Intergovernmental Panel on Climate Change, the UN’s lead climate change body.
“We now face a more dangerous future, with further risks and damages locked in,” says the report.
“We have reached the endgame and if we are to limit further disruption then we must dramatically step up the scale and pace of action. Inaction or delay in the face of so much evidence is in fact an active commitment to massive global climate disruption and damage.”
Professor Steffen said the impact of temperature rises did not go up in a linear fashion, and that 2 degrees of warming was far worse than 1.5 degrees.
“The issue here is that past inaction on climate change has cost us dearly. There is plenty of momentum in the climate system, it is like trying to turn a battleship around,” he said.
“The mantra I keep going back to is that every tenth of a degree matters.”
But Bill Hare, a lead author on the fourth IPCC assessment and founder of Climate Analytics, said he believes both the Climate Council and the Australian Academy of Science had found further evidence for the need for immediate and dramatic action. But he did not agree with the view that holding global temperatures rises to 1.5 degrees was virtually impossible.
His dissenting report, co-authored by his colleague Dr Carl-Friedrich Schleussner, said it is not possible to draw conclusions on temperature rises over short time periods used by the Climate Council report; that sea level rise is a lagging rather than leading indicator of climate change; and that the Climate Council had made mistakes in its interpretation of so-called carbon emissions budgets. They further question the report’s analysis of climate sensitivity.
“The evidence presented in the Climate Council of Australia report itself does not support their claim that 1.5°C will be exceeded,” they write.
Mr Hare told the Herald and The Age he believed the evidence of physics and economics showed that 1.5 degrees was still achievable and that the target itself was a critical policy tool supporting international efforts to tackle climate change.
“[The 1.5 degree target] has become mainstream in the global climate debate, it is why nations are talking about net zero by 2050 rather than 2070.”
Nick O’Malley is National Environment and Climate Editor for The Sydney Morning Herald and The Age. He is also a senior writer and a former US correspondent.