Implications of the Globally Increasing Atmospheric CO₂ Concentration and Temperature for the Australian Terrestrial Carbon Budget: Integration Using a Simple-Model

Abstract

A simple continentally aggregated model of the Australian terrestrial carbon budget (CQUESTA) integrates information on CO₂ and temperature effects and is applied to evaluating whether vegetation is absorbing anthropogenic CO₂. Information from the literature is used to parameterise CQUESTA. A standard set of parameters is adopted for exploratory purposes. Historical information is used to describe the average CO₂ concentration and temperature over the southern hemisphere from 1750 AD to the present. From the present to 2050 AD the 'business-as-usual' scenario described by the Intergovernmental Panel on Climate Change (IPCC) is applied.

The standard parameterisation of the model suggests that the changing CO₂ concentration and temperature regime since 1750 AD has been causing continuous net sequestration of carbon into Australian live vegetation and soils. The present modelled rate of net sequestration is of a similar magnitude to CO₂ emissions from continental fossil fuel burning and land clearing combined. The rate of sequestration is predicted to continue to increase until 2050 AD and beyond if atmospheric CO₂ concentration and temperature continue to increase. However, there remains considerable experimental uncertainty about the correct parameterisation of the model. The findings have implications for policies on greenhouse effect gas emissions.