Nature Climate Change.
The scientists say that while the land carbon buffer can provide "a valuable, cost-effective, short-term service in helping to reduce atmospheric carbon dioxide", in the bigger picture – including the environmental limits to soil carbon and the huge quantity of new emissions each year – considering carbon storage on land "as a means to 'offset' CO2 emissions from burning fossil fuels… is scientifically flawed."
The researchers say that the capacity of the land to remove atmospheric carbon and store it in vegetation and soil is limited to the amount previously depleted by land use. If all the carbon so far released by land-use changes – mainly deforestation – could be restored through reforestation this would "reduce atmospheric carbon dioxide at the end of the century by 40–70 parts per million (ppm)". Yet human activity including from burning fossil fuels has already pushed the level up by 120 ppm, and we are still adding 2–3 ppm every year. This is why soil carbon cannot act as an "offset" to the total volume of human emissions, past or future.
The research concludes that "there are strict, environmentally determined limits on the maximum amount of carbon that can be restored to land carbon stocks, and good reasons why this maximum will not be achieved". And because carbon dioxide once emitted into the atmosphere is long-lived, then "the most effective form of climate change mitigation is to avoid carbon emissions from all sources. This means that there is no option but to cut fossil fuel emissions deeply, and not to continue these emissions under the erroneous assumption that they can be offset in the long term by the uptake of carbon dioxide in land systems."
In other words, reliance on soil carbon – to the exclusion of programmes to cut fossil fuel emissions deeply – can only fail if the aim is to avoid hot, dangerous and then catastrophic global warming. Yet, that is precisely what the Abbott Liberal–National Party climate plan proposes to do.
In releasing "The Coalition’s plan for real action on Energy and ResourcesI in 2010", a supporting media statement made the priority clear:
The single largest opportunity for CO2 emissions reduction in Australia is through bio-sequestration and the replenishment of soil carbon in particular.'On the ABC's QandA on 16 August, 2010, Tony Abbott reiterated that his climate plan:
...basically... involves going to the market and buying abatements through soil carbon, through tree planting, through businesses that are prepared to change their processes to less emitting ones.And whilst oppositional spokesperson Greg Hunt provides a rider that "we will always select the lowest cost abatement, whether it is in the land sector, the waste sector, the resources sector, the power sector or through actions such as energy efficiency", his emphasis too always seems to be on soil carbon, as in this speech on 18 April 2013:
Our Direct Action Plan is a simple, low touch market mechanism. The Emissions Reduction Fund will not only reduce our emissions, it will improve Australia’s environment through a range of measures including revegetation, better land management and enhanced soil quality.It is clear that the Opposition is desperate not to put a tax or price on greenhouse emissions or to go near constraining the coal industry or the coal and gas-fired electricity generators in any way. Their policy is to give the big polluters a free ride, so whenever a little detail is squeezed from them about their plan, it is always about just one thing … soil carbon!
Two years ago, Hunt told Lateline that "a million hectares at a 150 tonnes of carbon dioxide equivalent per hectare" could be abated annually through soil carbon.
But as ABC's Steve Cannane reported:
... a new three-year CSIRO study into soil carbon raises serious doubts about those claims.And in May this year, as reported by the Sydney Morning Herald:
The figures released to Lateline tonight show, "In the parts of the national soil carbon program that studied soil carbon changes over time - most showed soil carbon changes that were within the range (0.3 - 2.0 tonnes of CO2-equivalent per hectare per year) or lower."
At the top end of that range, you'd need a land mass of at least 75 million hectares to abate 150 tonnes of CO2 equivalent. If you take the 0.3 per cent figure, then you'd need 500 million hectares, or two thirds of the land mass of Australia.
Climate change department officials told a Senate estimates hearing on Monday night that soil carbon and revegetation projects are currently expected to deliver just 3.7 million tonnes a year of emissions cuts by 2020. Labor says these new estimates blow a hole in the Coalition's direct action climate change policy, which suggested up to 85 million tonnes per year of carbon dioxide cuts could come from soil carbon projects alone by the end of the decadeThe soil carbon claims at the heart of Tony Abbott's climate plan do not add up, either in the detail or in the big picture story as to whether they can be a substitute for deep cuts and the elimination of fossil fuel emissions. If Tony Abbott and Greg Hunt were to say that carbon sequestration is important and necessary, but it cannot in isolation avoid a climate catastrophe if you do not at the same time have policies for deep cuts in new emissions leading to zero emissions, they would be more credible.