Over-simplifying the role soil carbon plays in the sequestration market could threaten future food production and lead farmers down a murky path of accounting protocol that doesn't match the realities of nature, argue academics and researchers.
The voices of criticism aimed at the Australian Carbon Credit Unit and its varied methodologies comes as the federal Government calls for input into its Agriculture and Land Sectoral Plan, with carbon emissions at its heart.
Detractors argue that farmers put themselves at financial jeopardy by entering into long-term agreements over an uncertain commodity - one that grows with the wet and disperses in drought.
"These risks will arise through potential costs associated with the permanence obligation of carbon projects, policy uncertainty and price volatility," state the authors of a new report funded by Lock The Gate.
The researchers, from Queensland University of Technology's faculty of law highlight concern that active farmland could be lost to passive sequestration as an active ACCU market drives big corporate polluters to buy their own farmland and harvest carbon credits for their own use - anywhere in the world.
The report says: "Reputex Modelling of the potential demand for ACCU's for Beetaloo Basin gas development has led to estimates of three million hectares of land needed for environmental and plantation forestry projects to offset a medium emissions scenario over 12 years."
"If demand for ACCUs increases rapidly, there is potential for rapid land use change, which can potentially cause short and long term economic and social impacts on regional communities.
"A lack of clear and transparent information from government was cited frequently as a problem for landholders both involved in projects or as landholders adjacent to carbon farming projects."
The anti-gas lobby is calling for better predictions of how many ACCUs will be required to reach net-zero by 2050.
A recent essay in The Conversation by a group of soil scientists and academics also criticised the humble ACCU, regarded by many in this emerging industry as the best of the lot when it comes to integrity.
In the lead-up to proposed changes to the federal government's carbon market safeguard method, the academics are calling for increased transparency that can prove permanence of carbon in the landscape.
"There has been too much focus on win-win when that isn't always so," argues sustainable soil scientist and essay co-author, Prof David Rowlings, also from QUT.
"The reality is these carbon projects are hard and we should accept that."
Teasing out what gains in soil carbon are due to wet weather and what came from good management is not a simple job, but one that needs to be done to prove the worth of an ACCU, he says, pointing out the time scale of a carbon project is 25 years but carbon credits are issued every five years, which coincides with ENSO cycles of wet and dry, clouding the picture of how much atmospheric carbon is being sequestered.
"Australia experiences massive climatic swings and there is no real way of (seeing its impacts on soil carbon), of telling that in the short term.
"There is a massive disconnect here. There is a need to push for more transparency."
Meanwhile, at state level, efforts by the Minns Government to enact its Climate Change Bill and commit to net zero by 2050 will not be supported by The Greens because that party says it does not go far enough.
Part of that journey involves an ACCU that can prove its value as a climate mitigator.
"Intensifying carbon drawdown and sequestration across the landscape is an essential part of how we achieve our net zero commitment, (but) any carbon credit scheme must strictly adhere to the highest integrity principles and be based on genuinely good carbon accounting methodologies," said Greens senator and chair of a government inquiry into climate legislation, Sue Higginson.
"The federal Government's safeguard mechanism, which is supposed to ensure integrity and confidence in our Australian Carbon Credit Unit scheme, is out of balance and is biased towards big polluters, like the fossil fuel industry. This means that other industry sectors are doing the heavy lifting of emissions reductions.
"What we need most, rather than allowing big polluters to keep profiting, is governments to provide more incentives to land managers to build and farm carbon to get us to net zero as fast as we can."
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