The farmer must guarantee to keep the carbon in the soil for 100 years, under the Permanence Principle, an “Integrity Standard” enshrined in the Carbon Credits (Carbon Farming Initiative) Act 2011. (Part 7, Div. 1, clause 87 (1); Part 9, Div. 3, clause 133 (f)). The Permanence Principle was developed for biological sequestration on the grounds that some or all of the carbon removed from the atmosphere may ultimately return to the atmosphere. This has led to the idea that offsets based on ‘avoided emissions’ are of superior quality to those based on sequestered carbon because buyers can be more confident that the abatement they represent is ‘real’. But a close look reveals that ‘avoided emissions’ offsets are no more secure than soil carbon offsets.
“Avoided emissions” usually involves reduced use of fossil fuels. It is assumed that if a tonne of fossil fuel is not used, its emissions are avoided forever.  However that unburned fossil fuel may still be mined and burned later. In fact, a tonne of new emissions avoided today will almost certainly mean higher emissions in the future because the price of fossil fuel will be lower than renewable energy and these inexpensive resources will still exist. Unless their use is banned, which is unlikely, they will be available. The idea that avoided fossil fuel emissions today are avoided forever is therefore based on a fiction. Either the Permanence Principle applies to avoided emissions – the seller guarantees that the coal or oil will not be burnt for 100 years – or the requirement should be removed from soil carbon sequestration.
Throughout 25 workshops with Australian farmers on the subject of offsets trading, conducted by Carbon Farmers of Australia during 2010 and 2011, not one farmer was willing to commit to 100 year contracts. Therefore, to deliver the co-benefits that soil carbon offers, soil carbon offsets cannot be evaluated by the same criteria as used for avoided emissions.
Soil carbon offsets represent real abatement: they are purpose built to play a unique role in the global strategy to manage Climate Change for least impact. They also represent a significant value proposition for buyers in terms of the co-benefits they generate.
 “Once savings of fossil fuels have been made, those savings are permanent even if fossil-fuel use patterns revert back to those before savings had been made.” Kirschbaum, M.U.F.: 2006, ‘Temporary carbon sequestration cannot prevent climate change’, Mitigation and Adaptation Strategies for Global Change 11(5-6), 1151-1164.
 “Many LUCF activities alter C fluxes to and from the atmosphere several decades into the future, whereas fossil-fuel emissions avoidance has immediate effects.” Fearnside, P.M., Lashof, D.A. and Moura-Costa, P.: 2000, ‘Accounting for time in mitigating global warming through land-use change and forestry’, Mitigation and Adaptation Strategies for Global Change 5(3), 239-270.
 Herzog, Howard, Ken Caldeira, and John Reilly. "An issue of permanence: Assessing the effectiveness of temporary carbon storage." Climatic Change Aug. 2003 Vol 59, Iss. 3. 29 Oct. 2008 “Conventional wisdom associates avoided emissions with reduced use of fossil fuels (e.g., from improving energy efficiencies, increasing conservation, shifting to non-fossil energy sources, etc). It is argued that if a ton of fossil fuel is not used, its emissions are avoided forever. However… the idea that a ton of fossil emissions avoided today is avoided forever is not necessarily an accurate characterization of the problem because that unburned fossil fuel may still be mined and burned later. In fact, economic considerations lead one to conclude that a ton of avoided emissions today will, absent an absolute quantity constraint on emissions in all regions through time, mean higher emissions in the future. The simple reasoning is that the price path of fossil fuel will be lower in the future because these inexpensive resources still exist and therefore the future use of fossil fuels and carbon emissions would increase. Thus, there will be leakage into the future from avoided emissions that is analogous to the leakage of carbon from sequestration reservoirs. The temporal leakage from a carbon policy is analogous to well recognized spatial leakage that occurs when only part of the world undertakes a carbon policy. In other words, the idea that avoided fossil fuel emissions today are avoided forever is in error.”