Queensland forests are being cleared at almost twice the rate reflected in national greenhouse gas emissions, new analysis suggests, prompting questions about the climate data that Australia reports to the United Nations.
The study of data from Queensland’s statewide landcover and tree study (Slats) shows 455,756 hectares of forests were cleared across the state in 2018-19.
It is at odds with the amount of deforestation recorded under the national carbon accounting system that informs greenhouse gas emissions accounts. The national system found on average 245,767 hectares were cleared each year across 2018 and 2019.
Martin Taylor, a former conservation scientist with WWF Australia and now an adjunct senior lecturer at the University of Queensland, said it reinforced earlier claims that national deforestation emissions were likely to be higher than what the country had reported at international climate negotiations.
“There’s been this glaring disconnect between Queensland and national data for so long,” he said.
The difference matters because changes in land clearing have played a central role in allowing Australia to say it is meeting climate targets.
According to national greenhouse accounts, there has been a dramatic reduction in emissions from land clearing and forestry since 2005, largely due to a reduction in forest destruction in Queensland after changes in state laws. It allowed the Morrison government to claim a 19.6% cut in national emissions since that year.
In reality, little of this drop has been the result to steps taken by the federal Coalition. If land clearing and forestry are excluded, national emissions are down less than 2% since 2005.
If the national data for land clearing and forestry emissions are incorrect, as the analysis suggests, it would mean the government could claim only a much smaller emissions cut over the past 16 years. It would make it less likely Australia was on track to meet the Coalition’s target of a 26-28% cut in emissions by 2030.
The national and Queensland accounts differ in part because the federal data only counts clearing of forest to bare ground while the state data records all clearing, including of sparse woodland and even when the plant growth was only partly cleared.
Taylor aligned the two systems by filtering the Queensland data to match the national definition of primary deforestation and re-clearing of secondary forests. His analysis did not attempt to estimate the resulting emissions from the clearing.
Taylor said the discrepancy appeared to be due largely to errors in woody cover mapping in the National Greenhouse Gas Inventory. The level of agreement between the two systems was “surprisingly and shockingly low”, he said.
Unlike Slats, the national estimates are not used for any compliance issues where accuracy can be critical in court cases. Queensland officials will often visit sites in person to compare the satellite imagery – generated down to just 30cm, fine enough to detect individual trees – with what they can verify on the ground.
Taylor said that federal officials were “only interested in coming out with a number for the nation”. “As far as they’re concerned, it’s good enough for that,” he said.
A spokesperson for the federal energy and emissions reduction minister, Angus Taylor, rejected the Queensland findings, and said Australia’s emissions reporting was prepared by officials in accordance with United Nations Framework Convention on Climate Change [UNFCCC] guidelines.
“Any suggestion that the inventory has underreported emissions from land clearing is incorrect and wrong,” the spokesperson said. “The methods and data used are reviewed each year by a team of international experts assembled by the UNFCCC.”
The government spokesperson said a comparison of land-clearing rates between 1990 and 2018 showed the national database picked up 9% more clearing than the Queensland data.
Martin Taylor disputed this. He said the government comparison compared clearing of any woody vegetation, including sparse shrubs, while his report looked at forests. He said it showed the national data picked up much less deforestation than the Queensland data.
The Queensland government delayed the release of the 2018-19 data so it could access improved imagery, including from a European satellite system.
Queensland’s environment minister, Meaghan Scanlon, declined to comment on the dispute but said accurate information was “vital to making sure you can make informed decisions”.
“That’s why our world-leading scientists have helped develop Slats, updated our methodology and have used the most current technology to make sure we’re accurately tracking vegetation in Queensland,” Scanlon said.
Federal Labor was asked for its response to the Queensland data. It highlighted previous comments by Chris Bowen, the party’s climate change spokesperson, about an ALP promise to review the integrity of Australian carbon credits – some of which are generated by restoring vegetation and protecting existing forests – if the party wins office.
Polly Hemming, from the Australia Institute, said the model used by the federal government to measure land-sector emissions was “clearly deficient and something urgently needs to be done about that”.
“Land clearing in NSW and Queensland is increasing dramatically, but the full extent of this is clearly not being reflected in our international climate accounts as Australia consistently reports that its forests are a net carbon sink,” Hemming said.
“Australia shouldn’t be leaning so heavily on the land sector in the first place. At some point it’s going to come back to bite us.”
• Imagery supplied by the Planet Application Program Interface: In Space for Life on Earth, that can be sourced from https://api.planet.com.
