Save the climateClimate policy – effective & fair
Home Deutsche Startseite
Models, tools and documentation

Tools for Paris-compatible NDC reference values

Excel tools, web apps and methodological papers for distributing global CO₂ budgets and deriving plausible national emission pathways.

Short introduction

Core question: distribution of a global CO2 budget

CO2 remains in the climate system for a long time. Therefore, remaining global CO2 budgets correspond to specific limits of global warming. Key statements from the IPCC's Sixth Assessment Report on remaining CO2 budgets are summarised here.

However, the specific global budget used as a reference must ultimately be decided politically on the basis of the current state of scientific knowledge. Such a global budget raises the question of how it can be distributed among countries in a fair and economically reasonable way. Such a distribution should provide important guidance for the Paris Agreement's ambition mechanism and for the regular updating and strengthening of Nationally Determined Contributions (NDCs).

Two models and corresponding tools are presented here. Both involve distributing a global budget and determining national paths:

  • the Regensburg Model (RM) and
  • the Extended Smooth Pathway Model (ESPM)

Tools based on the Regensburg Model Scenario Types are also offered for the determination of emission paths that are compatible with a predefined budget.

Basic idea behind the Regensburg Model Scenario Types RM 1 - 6 (here is a short description)

With the help of the Regensburg Model Scenario Types, global or national emission paths can be determined that meet a given budget. The scenario types differ mainly in their assumptions about the trajectory of annual changes in emissions (here are exemplary courses). This approach is particularly useful when it comes to making political decisions about emission paths.

Web app: https://paths.climate-calculator.info

Publication: Zenodo, Mathematical Description of the Regensburg Model Scenario Types RM 1 – 6 Download

Basic idea behind the Regensburg Model (RM)

  1. Global paths: Global emission paths are determined that are compatible with a global CO2 budget to be specified. For this purpose, the RM tool provides the Regensburg Model Scenario Types RM 1 - 6 (see above).
  2. National paths: National emission paths are derived from these global paths with the Regensburg Formula, which leads to the convergence of per capita emissions (see mathematical description: Download; exemplary course of per capita emissions here).

Web app: https://RM.climate-calculator.info

Publications:
  • Journal "Climate Policy", 2016, The Regensburg Model: reference values for the (I)NDCs based on converging per capita emissions Download
  • Zenodo, Calculation of Paris-compatible Emission Targets for the Six Largest Emitters with the Regensburg Model Download
  • Zenodo, Paris-compatible National CO2 Budgets for the Six Major Emitters Based on the Regensburg Model with Converging Per Capita Emissions Download

Basic idea behind the Extended Smooth Pathway Model (ESPM; brief background Download)

  1. National budgets: A predefined global CO2 budget is distributed to countries. The ESPM tool offers a weighted distribution key that takes into account population and emissions in a base year (here: 2019).
  2. National paths: The ESPM tool offers the Regensburg Model Scenario Types RM 1 - 6 (see above) to derive plausible national paths that adhere to a national budget.

Web apps

Publications:

  • Wirtschaftsdienst, 2/2021, Berechnung Paris-kompatibler Emissionspfade mit dem ESPM am Beispiel der EU, Download
    • Extended update published on Zenodo (with exemplary reference values for the EU and Germany) Download
  • Zeitschrift für Umweltpolitik & Umweltrecht (ZfU), 9/2021, Calculation of Paris-compatible emission targets for the six largest emitters
    • Extended update published on Zenodo Download
  • Zenodo,  A Feasibility Stress Test of Collectively Paris-Compatible National CO₂ Targets

↑ Back to top

Download tools

Calculation of national emission paths and targets for all countries in the world that are compatible with a specified global CO2 budget 2020 - 2100

The table can be moved horizontally on small screens.

 

Regensburg Model (RM)
Extended Smooth
Pathway Model (ESPM)
download Excel tool from Zenodo platform
preview of the tool in the browser
instruction for the tool
Download
Download
method national paths are derived from a global path using the Regensburg Formula national paths are derived that adhere to a given national budget
allocation approach converging per capita emissions (example) weighted distribution key for a global budget with "emissions" and "population" as factors to be weighted
selectable parameter to map climate justice
convergence level weighting population
emission paths The Regensburg Model Scenario Types (RM 1 - 6) are used to derive paths that are compatible with a specified budget.
► see mathematical description of the RM Scenario Types: Download; exemplary courses
scenario types RM 1 - 6 are used to determine global emission paths scenario types RM 1 - 6 are used to determine national emission paths
data base
EDGAR: With this database, the EU provides the emissions of all countries in the world due to the use of fossil fuels (excluding international shipping and aviation; ISA) and cement production.
For the handling of land-use change emissions (LUC) in the tools, see this paper: Download
exemplary results Here you will find an overview of the available ESPM tools and results.
relationship between
ESPM and RM		 Depending on the chosen global path and the chosen convergence level, there is an implicit weighting of the population in the resulting national budgets across all countries in the RM (see proof in the mathematical description). The use of this implicit weighting as an explicit weighting in the ESPM leads to very similar results as in the RM. The results in the RM can therefore also be generated in the ESPM if the weighting of the population is specified accordingly. The implicit weighting can be calculated in the RM tool and is given above in the exemplary results in the RM for all countries in the world.
last publication
Calculation of Paris-compatible emission for the six largest emitters

focus targets: Download - published on Zenodo
focus budgets: Download - published on Zenodo

Download - published on Zenodo
web apps

national-budgets.climate-calculator.info

Determination of emission paths that adhere to a given budget using the Regensburg Model Scenario Types

The table can be moved horizontally on small screens.

 
ESPM approach: Set budget and determine emission paths
 
determine global paths
determine global or national paths
download Excel tool from Zenodo platform
preview of the tool in the browser
instruction for the tool
Download
Download
background

The challenge of determining plausible emission paths is particularly evident at the global level. Therefore we have decoupled determining smooth global paths in a separate tool.

With this simple tool, global or national emission paths can be derived that meet a specified budget.

This tool is particularly suitable if

  • a global or national budget is already known and the first interest is in compatible emission paths,
  • the focus is on getting to know the RM Scenario Types Download or
  • a database other than EDGAR is to be used.
additional feature Contains the illustrative IPCC SR1.5 paths P1 - P4 (LED, S1, S2, S5).  
data base
  • Global Carbon Project
  • IPCC SR1.5

The tool does not contain any data (with the exception of global emissions, the EU and Germany). The required data for all countries in the world can be provided with the following tools:
exemplary results   Here you will find an overview of the available ESPM tools.
method The tools use the Regensburg Model Scenario Types (RM 1 - 6) to determine emission paths that are compatible with a given budget. These scenario types differ in the assumption about the trajectory of annual changes in emissions (see mathematical description: Download; exemplary courses).
last publication   Berechnung Paris-kompatibler Emissionspfade mit dem ESPM am Beispiel der EU Download; published on Zenodo
web apps

only RM-6 (linear paths):
https://global-paths.climate-calculator.info

  

Easy access to results of the models based on framework data specified by you

↑ Back to top

Implicit and explicit weighting of the population

Tools for analysing the weighting of population and emissions in the allocation of a global CO₂ budget.

↑ Back to top

Comparison of similar approaches

Resource Sharing Models

Resource sharing models directly address the allocation of a remaining global budget. This article will therefore give an overview of the properties of resource sharing models that, in principle, use current emissions and population as a distribution key. The following models are compared: Regensburg Model (Regensburg Formula), Contraction & Convergence (C&C), Smooth Pathway Models (Smooth Pathway Formula from Raupach and Extended Smooth Pathway Model), Chakravarty et al. (cap per capita emissions), Höhne et al. (common but differentiated convergence; CDC).

↑ Back to top

Notes on macros in Excel tools

Some Excel tools contain macros. You can remove the macros by saving the downloaded xlsm file as an xlsx file. The key macro "Goal Seek" has the function of determining the free parameters in the scenario types in such a way that the specified budget is adhered to. You then have to do this individually for each scenario type in the sheet "goal seek" using the target value search (goal seek) integrated in Excel.

We have published the code of the macro "Goal Seek" and the corresponding bas file on Zenodo: https://doi.org/10.5281/zenodo.7494168.

↑ Back to top

Mathematical papers

Publications overview

Open the overview of our publications.

↑ Back to top