Abstract

Both supply and demand factors suggest that the price ascribed to a carbon flux into or out of the atmosphere might rise through time. When this is so, a single productive forestry cycle entails both early sequestration at low prices and late volatilisation at higher prices of carbon. Hence the cycle apparently has a negative carbon account, even if in every future time period its effect on atmospheric CO₂ stock seems to be non-detrimental. Costing carbon via its lagged long-term effects on global conditions (atmospheric and oceanic CO₂ and temperature) shows that a single production cycle which is overall carbon-neutral might indeed be detrimental. While the effect would be mitigated or reversed by discounting carbon flux values, in practice there is debate about whether such values should be discounted. Forest economists' habitual mode of analysis entails bias in treatment of the times within a forest cycle, and this is a cause of negative values. Combining carbon flux cycles into a normal forest structure, or a repeated replanting sequence, does produce a positive carbon account. Another option is growing a forest but not harvesting it. However, with rising carbon price and limited afforestable area, an even better alternative, apparently, is to delay any of these options, for as long as prices rise. To justify immediate planting would need other benefits of so doing to be invoked, or the case for rising prices to be rejected. Because of its long-term opportunity cost, such planting should complement emissions reduction, not be an offset that justifies emissions.