These are:

• Get away from any farm-by-farm test which asks, ‘Would you have done this without carbon finance or not?’ The counter-argument—that a carbon-sequestering project wouldn’t have proceeded without carbon finance—can't be proved.

• Identify carbon-conservation practices that add to farm productivity, and can sequester carbon in quantities that can earn carbon offset credits.

The practice in question must meet “additionality” criteria: the rule which says that to qualify for carbon credits, a practice must be additional to what the farmer would have practised anyway.

That implies that the practice must be seen by farmers to be risky, or financially impractical.

• Establish the baseline take-up of a certain carbon-conservation practice among farmers in a specific area: for example, that less than 1pc of grain growers in Central Queensland have introduced minimum-till over the past decade (a made-up figure).

Project that trend five or 10 years into the future to establish a baseline.

Get ABARE involved; get it to confirm uptake rates.

• From that point, pay carbon benefits on an agreed system to anyone who adopts the carbon-conservation practice.

• Review uptake of the practice in five years, and create a new baseline according to the new trend line.

Farmers who invested in the new practice when the first baseline was established are “grandfathered”, and earn a stream of carbon revenues for another 10 years.

• “Industry by industry, crop by crop, come up with baselines.

But don’t fiddle around with them, or require farm-by-farm audits. The transaction costs in managing a scheme like that, and the risks, are enormous,“ Dr Newcombe said.