# Model Documentation

### | Version 4.0

created with goxygen 0.21.1

# 39_landconversion

# Land Conversion Costs (39_landconversion)

## Description

The land conversion cost module calculates costs for the conversion from one land type to another (e.g. conversion from forest to cropland). Land conversion plays an important role for the overall model dynamics, in particular in terms of CO2 emissions from land-use change. Expansion of agricultural land is one of the major options in the model to increase agricultural production, besides yield increases (13_tc, 14_yields) and trade (21_trade).

## Interfaces

Interfaces to other modules

### Input

module inputs (A: global_static_aug18)
| Description | Unit | A
--- | --- | --- | ---
pm_interest (i) | Current interest rate in each region | \(\%/yr\) | x
vm_carbon_stock_reduction (j, land, c_pools) | Reduction in carbon stocks compared to previous time step | \(10^6 tC/time step\) | x
vm_landexpansion (j, land) | Land expansion | \(10^6 ha\) | x

### Output

module outputs
| Description | Unit
--- | --- | ---
vm_cost_landcon (j, land) | Land conversion costs | \(10^6 USD_{05MER}/yr\)

## Realizations

### (A) global_static_aug18

In the global_static_aug18 realization, per hectare land conversion costs are separated into costs for expansion of cropland, pasture and forestry (establishment costs) and costs for clearing of primary forest, secondary forest and other natural land (clearing costs). We assume a global cost factor of 8000 USD/ha (static over time) for establishment of managed land. For clearing of natural vegetation we assume a global static cost factor of 5 USD/tC (based on Kreidenweis et al. (2018)).

Land establishment costs apply on expansion of cropland, pasture and forestry. Land clearing costs apply on reduction of carbon stock in primary forest, secondary forest and other natural land. The sum of land establishment and land clearing costs in the current time step is multiplied with an annuity factor to distribute these costs over time.

\[\begin{multline*} v39\_cost\_landcon\_annuity(j2,land) = \left(vm\_landexpansion(j2,land) \cdot i39\_cost\_establish(land) + vm\_carbon\_stock\_reduction(j2,land,"vegc") \cdot i39\_cost\_clearing(land)\right) \cdot \sum_{cell(i2,j2)}\left(\frac{pm\_interest(i2)}{\left(1+pm\_interest(i2)\right)}\right) \end{multline*}\]

Land conversion costs in the current time step consist of the annuitized costs for land conversion in the current time step `v39_cost_landcon_annuity` and the land conversion costs from the past `pc39_cost_landcon_past`.

\[\begin{multline*} vm\_cost\_landcon(j2,land) = v39\_cost\_landcon\_annuity(j2,land) + pc39\_cost\_landcon\_past(j2,land) \end{multline*}\]

> Limitations Data availability for land conversion costs is very limited.

## Definitions

### Objects

module-internal objects (A: global_static_aug18)
| Description | Unit | A
--- | --- | --- | ---
i39_cost_clearing (land) | Global land clearing costs | \(USD_{05MER}/ton C\) | x
i39_cost_establish (land) | Global land establishment costs | \(USD_{05MER}/hectare\) | x
p39_cost_landcon_past (t, j, land) | Costs for landconversion from the past | \(10^6 USD_{05MER}/yr\) | x
pc39_cost_landcon_past (j, land) | Costs for landconversion from the past in the current time step | \(10^6 USD_{05MER}/yr\) | x
q39_cost_landcon_annuity (j, land) | Calculation of cellular annuity costs of landconversion | \(10^6 USD_{05MER}/yr\) | x
q39_cost_landcon (j, land) | Calculation of cellular landconversion costs | \(10^6 USD_{05MER}/yr\) | x
s39_cost_clearing | Global land clearing costs | \(USD_{05MER}/ton C\) | x
s39_cost_establish | Global land establishment costs | \(USD_{05MER}/hectare\) | x
v39_cost_landcon_annuity (j, land) | Annuity costs of landconversion in the current timestep | \(10^6 USD_{05MER}/yr\) | x

### Sets

sets in use
| description
--- | ---
c_pools | Carbon pools
i | World regions
land | Land pools
t(t_all) | Simulated time periods

## Authors

Florian Humpenöder, Jan Philipp Dietrich, Ulrich Kreidenweis

## See Also

10_land, 11_costs, 12_interest_rate, 52_carbon

## References

Kreidenweis, Ulrich, Florian Humpenöder, Laura Kehoe, Tobias Kuemmerle, Benjamin Leon Bodirsky, Hermann Lotze-Campen, and Alexander Popp. 2018. “Pasture Intensification Is Insufficient to Relieve Pressure on Conservation Priority Areas in Open Agricultural Markets.” Global Change Biology 0 (0). doi:10.1111/gcb.14272.