Australia’s fair share of action to give the world a chance of keeping global heating to 1.5C would mean reaching net zero greenhouse gas emissions by the year 2038 – more than a decade ahead of the government’s schedule, according to new scientific analysis.
To stay on track to keep global heating of 1.5C within reach – a goal the climate change and energy minister Chris Bowen has described as vital – Australia’s 2035 target would need to see a cut of 90% on 2005 levels by 2035, the analysis says.
The research, from two leading scientists who contributed to the UN climate panel’s assessment of how quickly global emissions will need to drop, points to how far Australia has to go to legitimately claim its targets are in line with the 1.5C goal.
The Albanese government has already updated the country’s target to a 43% cut on 2005 levels by 2030 – an improvement on the Morrison government’s 26% commitment.
In a briefing report commissioned by WWF-Australia, associate professor Malte Meinshausen and Dr Zebedee Nicholls of Climate Resource say the improved target would need to have been “at least 67%” to have been in line with 1.5C.
While Australia has a net zero target by 2050, Meinshausen and Nicholls say this net zero date should be 2038 based on Australia’s “fair share” of effort.
Nicholls said: “We are at the point where we need to be going for maximum possible ambition. Every mitigation option that we have we need to look at seriously.
“This is the minimum that Australia should be looking at if we’re serious about 1.5C.”
The concept of what a “fair share” of effort represents is contested and not agreed between countries.
The new analysis considers how much the entire planet could emit – known as the carbon budget – while giving a 50% chance of keeping global temperatures to 1.5C.
The new analysis gives Australia a 0.97% share of that global budget, a figure taken from a 2014 Climate Change Authority report that sees developed countries making faster cuts to allow developing countries more time to decarbonise.
That 0.97% share is considered generous, the authors said, because Australia makes up only 0.33% of the planet’s population.
According to Climate Resource, the government’s current plans would lead to 7.6bn tonnes of CO2-equivalent being released by Australia between 2021 and 2050, which was “roughly double” a budget of 4bn tonnes “for a 50% chance of staying below 1.5C.”
Prof Frank Jotzo, a climate policy expert at Australian National University, said it was “impossible to pin down” what the “fair share” of any country’s efforts on emissions reductions would look like “because there are so many value judgments that need to be made”.
But he said to pass any “plausibility test” for a 1.5C-aligned commitment, emissions reductions would need to be “extremely rapid, deep and sustained” and Australia’s current policy ambition was “not in line with 1.5C”.
Keeping global temperatures close to 1.5C would reduce the impacts of heatwaves, sea level rise, temperature extremes and give ecosystems such as Queensland’s Great Barrier Reef a better chance of avoiding collapse.
The government will set its 2035 target in 2025 after the Climate Change Authority issues advice in 2024. The authority is in the middle of a community consultation process on that issue.
Last month, the environment minister, Tanya Plibersek, wrote to Unesco to promote the federal and Queensland government’s steps to conserve the reef after a UN-backed monitoring mission called for a series of new measures.
In the letter, Plibersek wrote the government was committed to setting “successively more ambitious emissions reduction targets” that would be “in alignment with efforts to limit global temperature increase to 1.5C”.
Richard Leck, head of oceans at WWF-Australia, said: “Australia needs to do its fair share. We can’t expect the rest of the world to do the heavy lifting to save the Great Barrier Reef. Australia has to set the example and give the reef a fighting chance.”
In a statement, Unesco said together with its science advisers it was finalising an assessment of the reef that was “expected to be public in July” and “a final decision over whether Australia’s commitments are sufficient or not will be decided by the world heritage committee in September”.
Guardian Australia asked minister’s Bowen’s office if the government considered its 2050 date for net zero to be in line with the country’s “fair share” of global effort to keep temperatures to 1.5C, and what criteria it would use to make that assessment.
Those questions were not answered, but a spokesperson said the government was implementing strong policies to achieve its “ambitious” 2030 and 2050 targets.
Under the new Climate Change Act, the Climate Change Authority’s advice on the 2035 target to be updated in 2025 would give “specific consideration to the temperature goals” of the Paris agreement, the spokesperson said.
Queensland is the largest-emitting state but its 2030 emissions reduction target remains stuck at 30% by 2030 and well behind other states.
The Queensland environment minister, Leanne Linard, said 2021 data showed the state had almost reached its 2030 goal “nine years ahead of time” and the government was “committed to meeting its overall goal of zero net emissions by 2050, in line with leading global economies”.
