A carbon accounting model for a carbon crisis

This is the first draft of a carbon accounting model that looks at the world’s forests, and their owners, as one of the mechanisms to increase carbon uptake as one of the strategies to mitigate current levels of carbon in the atmosphere.

We are using the double accounting method Assets, Liabilities and Equity in order to be able to put the model into the minsky software. Minsky is a system dynamics modelling software that easily allows “what if” calculations. The ulterior motive is to help policy makers understand the role of the forest in carbon mitigation. It also aims to connect carbon and money so that policy makers can explore the role of economic instruments to encourage forest owners to participate in the great carbon sequestration needed.

Million tonnes of CO2 equivalent

As you see from the above, net forest carbon absorption is nearly as large as the carbon emitted by consumption abroad. Whilst this is no easy subject, full of complications, it may help policy to have a helicopter view. Note that emissions from burning wood come mostly under industry, biogen, 11.26 million tonnes

This is just a draft, written to encourage systems thinkers and forest ecologists alike to contribute. Note to simplify we use the units of metric tons of carbon throughout.

The diagram above shows the basic concept. One hectare of forest has:

A theoretical maximum C uptake – depending on the percentage of cover. 100% cover gives maximum uptake.

An actual uptake, and reduced uptake and C content after felling.

Note that the forest floor, the soil, contains more carbon than the trees, and felling the trees results in a release of carbon for some ten years until the forest has started to grow back.

Full functionality is achieved, at least in Swedish forests after trees reach 60-70 years. They go on taking up carbon until they reach 200 years old.

In terms of releasing carbon to the air, some 15% of timber harvests is used in building, with a half-life of 30 years.

The rest has a life of about one year before being combusted. This means 85% of the harvested forest ends up as atmospheric carbon the year after.

If we see the shortfall in carbon uptake by the forest as a liability (on humanity) and the actual uptake as equity, we can start to model this in accounting terms.

List of parameters

  • Carbon in forest 110 tonnes per hectare
  • Carbon in forest soil 160 tonnes per hectare
  • Carbon sequestered in mature forest (at least) 1 tonne ha 1 year1 ha
  • Carbon lost 1 tonne ha-1 yr-1

Other input information needed:

  • The area of the property in ha
  • The % forest cover
  • The % forest planned for felling
0.4t ha-1year-1 ha1 t ha−1 year−1 haMature forest stands Carbon uptake tons per hectare /yr
?1.77 t ha−1 year−1 haMature forest soils Carbon uptake tons per hectare /yr
1t ha-14t ha-1Average C emission of felled forest under 10 years, includes soil loss

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: