KEY POINTS:
The success of any emissions trading scheme will depend on how reliably we can quantify greenhouse gas emissions and removals. Put simply, you can't manage emissions unless you can measure them.
Carbon accounting is complicated by the fact that New Zealand does not yet have a national inventory accurate enough for full Kyoto reporting, especially when it comes to indigenous forests, pasture land and soils. Nor does it have a map of land cover at 1990, the Kyoto benchmark year.
The problem is not confined to carbon emissions. New Zealand is the only developed country where pastoral animals contribute as much to greenhouse gas emissions as people.
Acquiring reliable data for emissions from pastoral farming means having an understanding of numerous variables, including an animals metabolic rate and energy requirements, the composition of its diet and feed intake, its age, breeding status and performance.
The most difficult problem of all is how these things interact to determine emissions. This can be achieved only from an understanding of underlying processes at the farm level, and then aggregated for a national inventory and archive.
New Zealand-specific figures and the means by which they are derived must stand up to international scrutiny and the audit requirements set in place by the international "cap and trade" marketplace.
Uncertainties internationally in assembling inventories of greenhouse gases are larger than many realise, and what figures do exist are generated from theoretical models. For example, guidelines for nitrous oxide inventory estimates were, until 2007, based entirely on methodologies using models.
Research based on direct measurement reported in 2007 from the company NzOnet (Landcare Research) uncovered results that showed that these models were not appropriate for use in New Zealand. For example, in contrast to an internationally estimated emission factor of 2 per cent from cattle urine, New Zealand measurements averaged 1 per cent. The same value was obtained for sheep.
These New Zealand-specific figures from the research reduced the inventory of nitrous oxide emissions from grazing animals by approximately 40 per cent.
NzOnet also found that New Zealand's diverse topography is a key consideration in determining emissions for pastureland. Livestock that graze steeper, drier hill country are likely to have lower nitrous oxide emissions compared with flat land.
There are other important problems. A grazing animal is not unlike a tree. Both sequester carbon for their lifetimes. For the animals, the carbon captured in grass and extracted from the air gets transformed to flesh and milk.
There is evidence that underground storage of carbon from the roots of grass and faeces mixed into the soil constitute a net carbon sink rather than a source, as is usually assumed.
When it comes to methane, it is not clear why methane emitted by farm animals counts as a net source of a greenhouse gas. The emissions from animals, whether from the lungs or the gut, are all produced from the food the animal took in. Animals do not add to the stock of atmospheric carbon and methane, they simply return it.
This is in contrast to human-caused carbon dioxide, which takes fossil carbon out of storage in the ground and pumps it into the atmosphere.
New Zealand appears to be the only country considering action over their bovine populations even though many countries have far more cattle. The biggest sources of human-caused methane are the rice paddies of Asian nations, which are not required to implement the Kyoto protocol.
The trade in carbon credits will depend on accurate accounting and reliable auditing so that there is not widespread corruption.
Already there have been many claims of fraud and misrepresentation over carbon offsets and trades.
In light of dodgy greenhouse gas inventories, this is not surprising. Compare carbon trading with electricity. In an electricity market, data on the amount bought and sold is accurate to +/- 0.2 per cent every 30 minutes. With carbon trading, very little can be measured accurately.
According to energy expert Bryan Leyland: "Carbon trading is the only commodity trading where it is impossible to establish with reasonable accuracy how much is being bought and sold, where the commodity that is traded is invisible and can perform no useful purpose for the purchaser, and where both parties benefit if the quantities traded have been exaggerated."
It is, therefore, an open invitation to fraud. For a workable scheme, what is needed is some good data. Right now we are working on just hunches.
* Chris de Freitas is an associate professor in the School of Geography, Geology and Environmental Science at the University of Auckland.
