COACCH damages
Climate impacts in MIMOSA are calculated using the COACCH damage functions, developed in 2023 (see van der Wijst et al., 2023).
Usage:
params = load_params()
params["model structure"]["damage module"] = "COACCH" # This is the default damage module, so this line is optional.
model = MIMOSA(params)
The COACCH damage functions are split in two parts: temperature-dependent damages (non-SLR, as a function of global mean temperature above pre-industrial), and sea-level rise damages (SLR, as function of global mean sea-level rise in meters):
With combined damages, the temperature-dependent curve includes SLR impacts and the separate SLR damage term is zero.
Temperature-dependent damages
The temperature-dependent damages are modeled as a quadratic damage function \(D(\cdot)\) of global mean temperature:
To calculate the damages, three transformations have to be taken from the above quadratic equation:
- The COACCH damage functions were created as function of temperature relative to 1986-2005, which is 0.6°C above pre-industrial. For this reason, the temperature is shifted by 0.6°C.
- The damages are scaled by a factor \(a_{\href{./#param__economics.damages.quantile}{q},r}\), which depends on the quantile \(\href{./#param__economics.damages.quantile}{q}\) of the damage function. This represents the uncertainty in the damage function. For median damages, this factor is \(\href{./#param__regional.COACCH.NoSLR_a%20%28q%3D0.5%29}{a_{0.5,r}} = 1\). The quantile can be set using the damage quantile parameter.
- Since we assume that until 2020 the climate damages are already incorporated in the baseline GDP, we subtract the damages of the initial time period \(t=0\).
Combining these three transformations, the damages are calculated as:
The regional functional form and the coefficients above describe the separate non-SLR curve. Combined curves use their own coefficients, selected by quantile and adaptation.
All the damage coefficients are region-dependent (see Damage functions and coefficients).
Temperature-dependent damages aggregated to the world, and comparison with the literature:
Source code in mimosa/components/damages/coacch.py
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Sea-level rise damages
In MIMOSA, sea-level rise damages are modelled separately from temperature dependent damages, as they occur on a different time scale: sea-level rise is a slow process with high inertia. Therefore, these damages are calculated as a function of global mean sea-level rise (SLR) in meters (calculated in the Sea-level rise component).
The SLR damages are calculated with the DIVA impact model (see Impact sectors used in the damage functions). These damages are available either with optimal adaptation (and include adaptation costs), or without adaptation. This can be chosen with the parameter coacch_slr_withadapt. By default, the optimal adaptation case is used.
Depending on the region, the SLR damages are modelled with different functional forms following from a best-fit regression. The SLR damages are either quadratic, linear, or logistic:
The values of \(\href{./#param__regional.COACCH.SLR-Ad_b1}{b_1}\), \(\href{./#param__regional.COACCH.SLR-Ad_b2}{b_2}\), and \(\href{./#param__regional.COACCH.SLR-Ad_b3}{b_3}\) are region-dependent and depend on whether adaptation is included or not. These are different values than the coefficients in the temperature-dependent damages. The functional forms depend on the regression of the underlying impact data (see Damage functions and coefficients) and are shown in the table below.
The coefficient links in the equations show the default, optimal-adaptation curve. Without adaptation, the corresponding regional inputs are the functional form, \(b_1\), \(b_2\), \(b_3\) and median scale factor.
| Region | SLR (with opt. adapt.) | SLR (no adaptation) |
|---|---|---|
| CAN | Linear | Quadratic |
| USA | Linear | Quadratic |
| MEX | Linear | Quadratic |
| RCAM | Linear | Quadratic |
| BRA | Linear | Quadratic |
| RSAM | Linear | Quadratic |
| NAF | Linear | Linear |
| WAF | Linear | Linear |
| EAF | Linear | Linear |
| SAF | Linear | Quadratic |
| WEU | Logistic | Linear |
| CEU | Logistic | Quadratic |
| TUR | Linear | Quadratic |
| UKR | Linear | Quadratic |
| STAN | Linear | Quadratic |
| RUS | Linear | Quadratic |
| ME | Linear | Quadratic |
| INDIA | Linear | Linear |
| KOR | Linear | Quadratic |
| CHN | Linear | Quadratic |
| SEAS | Linear | Linear |
| INDO | Linear | Linear |
| JAP | Linear | Linear |
| OCE | Linear | Quadratic |
| RSAS | Logistic | Quadratic |
| RSAF | Linear | Linear |
To calculate the SLR damage costs, two additional transformations have to be taken:
- Similar to temperature-dependent damages, the SLR damages are scaled by a factor \(a_{\href{./#param__economics.damages.quantile}{q},r}\), which depends on the quantile \(\href{./#param__economics.damages.quantile}{q}\) of the damage function. This represents the uncertainty in the damage function. For median damages, this factor is \(\href{./#param__regional.COACCH.SLR-Ad_a%20%28q%3D0.5%29}{a_{0.5,r}} = 1\). The quantile can be set using the damage quantile parameter.
- Since we assume that until 2020 the climate damages are already incorporated in the baseline GDP, we subtract the damages of the initial time period \(t=0\).
The SLR damage costs therefore become:
Source code in mimosa/components/damages/coacch.py
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Parameters defined in this module
params["economics"]["damages"]["scale factor"]: Manual scaling factor to increase or decrease damages. Type: float. Default: 1. Min: -inf. Max: inf.params["economics"]["damages"]["quantile"]: Damage quantile (Only used for COACCH). Type: enum. Default: 0.5. Allowed values: [0.025, 0.05, 0.16, 0.25, 0.33, 0.5, 0.67, 0.75, 0.84, 0.95, 0.975].
Source code in mimosa/components/damages/coacch.py
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Damage functions and coefficients
Visualisation of damage functions and damage coefficients
Download COACCH damage function coefficients
Impact sectors used in the damage functions
| Climate change impact area | Model source | Variable used in CGE |
|---|---|---|
| Agriculture | EPIC biophysical model and GLOBIOM model | (Change in) Crop yield |
| Forestry | G4M model | (Change in) Net physical wood production per hectare |
| Fishery | DBEM envelope model and DSFM food web model | (Change in) Fish catches |
| Sea-level rise | DIVA model | - Annual land loss due to submergence - Expected annual damages to assets - Expected annual number of people flooded - Annual protection costs |
| Riverine floods | GLOFRIS model | - Expected annual damages for the industrial, commercial, and residential sectors - Expected annual number of people flooded |
| Road transportation | OSDaMage model | Expected annual damages for the road infrastructure |
| Energy supply | Schleypen et al. (2019) | Changes in wind and hydropower production |
| Energy demand | Schleypen et al. (2019) | Changes in energy demand by households and by the industrial, agricultural and service sectors for coal, oil, gas, and electricity |
| Labour productivity | Dasgupta et al. (2022) | Changes in per capita production of value added |