Nature to the rescue: past drivers and future potential of the Australian land-based carbon offsets market

Figures & data

Table 1. Equation for linear regression of the landscape and market models.

loge[profit at full equity] = β*loge[maximum biomass value] + β*[project dummy] + β*loge([maximum biomass value]*[project dummy]) + ϵ
loge[profit at full equity]	Natural log of the PFE value
loge[maximum biomass value]	Natural log of the M value
[project dummy]	A dummy variable equal to 1 if the value comes from a project, and zero if sampled from a random point. This will describe the estimated level of the PFE value of a project relative to the intercept of the random points model.
loge([maximum biomass value]*[project dummy])	An interaction term, to separately assess the slope of the coefficient for the subset of values relating to the abatement projects
β	A coefficient
ϵ	An error term, with residuals expected to be normally distributed and with a mean of zero

Figure 1. Agricultural Profit at Full Equity (Marinoni & Navarro Garcia, 2018) versus Maximum Biomass Layer (Roxburgh et al., 2019) for the Australian landscape and approved abatement projects, segmented by project method. Log_e scale on both axes.

Table 2. linear regression model of the association between farm profits (PFE) and site biomass potential (M) for the Australian landscape and approved abatement projects.

	Estimated coefficient	Standard error	t value	Pr(>|t|)
Intercept	−1.1	0.0492	−22.36	< 2e-16 ***
loge Maximum biomass	1.1	0.0145	75.79	< 2e-16 ***
Abatement project dummy	−1.05	0.1987	−5.26	1.48e-07 ***
loge Maximum biomass * Abatement project dummy (interaction term)	0.25	0.05	4.98	6.67e-07 ***
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ‘ 1 Residual standard error: 1.188 on 6590 degrees of freedom (4270 observations deleted due to missingness) Multiple R-squared: 0.5083, Adjusted R-squared: 0.5081 F-statistic: 2271 on 3 and 6590 DF, p-value: < 2.2e-16 Residuals: Min    1Q   Median  3Q   Max −4.3287 −0.7284  −0.0372 0.6743  5.7505

Figure 2. Map of approved abatement projects and the biomass/agricultural profit layer (M/PFE) ratio for Australia.

Table 3. Highlighted offset project groups, with description.

Area	Mean M and PFE values	Number of projects	Predominant project type
1. South-west Western Australia	19 t and $4	70	Human induced regeneration
2. Tropical savannas	52 t and $11	93	Savanna burning
3. Woodlands of Queensland and New South Wales	40 t and $16	357	Avoided deforestation (n = 66) and human induced regeneration/managed regrowth (n = 291)

Marinoni, O., & Navarro Garcia, J. (2018). Agricultural profit map for Australia for 2010–2011. v1. CSIRO.

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Roxburgh, S. H., Karunaratne, S. B., Paul, K. I., Lucas, R. M., Armston, J. D., & Sun, J. (2019). A revised above-ground maximum biomass layer for the Australian continent. Forest Ecology and Management, 432, 264–275. https://doi.org/10.1016/j.foreco.2018.09.011

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