The key to Minister Burke’s problem called “Measurement”

A buyer of offsets is buying an ‘aggregated tonne’ from a large ‘aggregated pool’ of tonnes that have been ‘equalised’ ie., flux is statistically ‘compressed’ (peaks and troughs equalised). The buyer buys from an aggregated pool of tonnes as part of an aggregated pool of buyers. The significant variations at individual tonne level are eliminated by statistical smoothing.

• This approach was first noted by Sandor and Skees who say that we need not worry about how much carbon is sequestered on an individual paddock, because, while estimates at an individual level may be flawed, the error has ‘typical statistical properties’ and that estimating many individual parcels and aggregating them into a single parcel will improve the estimate significantly. (Sandor, R. L. & Skees, J. 1999. Creating a market for carbon emissions. Choices 3rd Quarter, pp 13-17.)

• A similar note was sounded by the Australian Farm Institute: “if measurement or estimation systems are robust and unbiased… the aggregate result for the combined scheme will be relatively accurate due to the effect of combining many estimates together.” (The New Challenge for Australian Agriculture: How do you muster a paddock of carbon?)

• Wholesale aggregators are already commonly used in carbon markets and the system for aggregation exists. The Australian Greenhouse Office recognized the benefits of aggregation in forest sinks, called ‘carbon pooling’.

• The world’s leadng soil carbon scientist Dr Rattan Lal also sees the way forward in pooling: “[A protocol to trade C credits] will require development of routinely usable techniques to measure change in soil C pool at landscape level over a time span of 1 to 2 yr.” (“Soil Science and the Carbon Civilisation”, Soil Science Society of America Journal, 71 (3), Sept-Oct 2007.)

• Another leading soil carbon scientist, Dr John Kimble, called for a ‘real world’ approach to soil carbon measurement, to make a market possible. "It is often pointed out that soils have a large amount of variability, but with knowledge of soil sciences and landscapes, variability can be described and sampling protocols can be developed to deal with this," writes Dr Kimble. "One reason I feel people say that soils vary and SOC cannot be measured is that we soil scientists focus on showing variability, not on showing what we know about the variability… We too often focus on this [variability], worry about laboratory precision and field variation and do not look at the real world where most things are based on averages and estimated data. We tend to focus on finding variation and not on using our knowledge of soil science to describe what we know. All systems vary, but in soils we focus on a level of precision and accuracy that may not have any relevance to the real world because we can take so many samples and look at the variation." (Kimble, J., "Advances In Models To Measure Soil Carbon: Can Soil Carbon Really Be Measured?", in Lal, R., Cerri, C., Bernoux, M., Etchevers, J., and Cerri, E., eds., Carbon Sequestration in Soils in Latin America, Food Products Press, Birmingham, NY, 2006) Dr Kimble recently retired from the US Department of Agriculture, National Resources Conservation Service, National Soil Survey Centre, Lincoln, Nebraska.