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Reference values to the NDCs resp. NDCs calculators:
Regensburg Model and Extended Smooth Pathway Model

Short introduction

Distribution of a global CO2 budget

CO2 affect the climate for a long time. Therefore, remaining global CO2 budgets correspond to certain limits of global warming (more information here).

Which concrete global budget we want to orientate by 2100, however, 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 amongst the countries in a fair and economically reasonable way. Such a distribution should be an important guidance of the ratchet up mechanism (ambition mechanism) of the Paris Agreement with Nationally Determined Contributions (NDCs).

Here two models are presented to calculate national paths and budgets that are compatible with a given global budget 2018 - 2100:

the Regensburg Model and
the Extended Smooth Pathway Model.

In addition, resource sharing models are compared and a tool for determining global paths is offered.

Basic idea behind the Regensburg Model (RM)

Global paths: Global emission paths are determined that are compatible with a global CO2 budget to be specified. For this purpose, the 'Tool_RM' provides six scenario types (RM 1 - 6), which differ in their assumptions about the property of the annual reductions.
National paths: National emission paths are derived from this global paths in the convergence period with the Regensburg Formula, which leads to the convergence of per capita emissions.

Basic idea behind the Extended Smooth Pathway Model (ESPM; inspired by Raupach et al.)

National budgets: A predefined global CO2 budget is distributed to countries. The 'Tool_ESPM' offers the use of a weighted distribution key that includes the 'population' and the 'emissions' in a base year (here: 2019).
National paths: The 'Tool_ESPM' offers the Regensburg Model scenario types RM 1 - 6 to derive plausible national paths from a national budget.

Download tools and papers

Excel tools for calculating national reference vlaues that are compatible with a given global CO2 budget 2018 - 2100

	Regensburg Model (RM)	Extended Smooth Pathway Model (ESPM)
Tool
Version of the tool	26.0	29.0
Preview ot the tool in the browser	here	here
Instruction for the tool
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	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
Paths: The RM Scenario Types 1 - 6 are used to derive paths that are compatible with a specified budget. ► See mathematical description of the RM Scenario Types:	scenario types RM 1 - 6 are used to determine global emission paths	scenario types RM 1 - 6 are used to determine national emission paths
Paper	Journal "Climate Policy" published online on 14 June 2016: The Regensburg Model: reference values for the (I)NDCs based on converging per capita emissions	working paper: Application of the ESPM to the EU objectives (in German)

Exemplary results according to the RM and the ESPM with different global budgets

Exemplary results according to the RM and the ESPM			global CO2 budget 2018 - 2100
			420 Gt	570 Gt	680 Gt

			Regensburg Model
Lists of national emission budgets and reference values for all countries according to the RM

			Extended Smooth Pathway Model
Lists of national emission budgets for all countries and reference values for the largest emitters according to the ESPM	weighting population	50%
		15%

Notes on the 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 in the RM. The use of this implicit weighting as an explicit weighting in the ESPM leads to very similar results as in the RM, as the overview of the results according to ESPM and RM shows for the largest emitters:
Overview results ESPM and RM for the largest emitters and different global budgets:

Determine global paths that meet a given global budget
In determining plausible global emission paths, the challenge before which we aside is particularly evident. Therfore we have decoupled determining smooth global paths in a separate tool.
Comparison similar approaches (Resource Sharing Models):
The following models are compared: Regensburg Formula, Contraction & Convergence (C&C), Smooth Pathway Models, Chakravarty et al. (cap per capita emissions), Höhne et al. (common but differentiated convergence; CDC)
- working paper: Comparison Resource Sharing Models
- Comparison Resource Sharing Models.xlsm (Preview of the tool in the browser here)
Remark on the tools
The Excel tools include macros. On request, the tools can be provided without macros and the macros as text or bas files for self-integration.
Mathematical Papers
- Resource Sharing Models - A Mathematical Description
  This paper shines the spotlight on the mathematical formulae of resource sharing models. It contributes to greater transparency and comparability through a uniform mathematical representation, by showing generalisations and mergers as well as similarities and differences between currently used models. It also contains mathematical proofs for specified properties of the models.
  In Chapter 2 we consider models with a limited convergence period, at the end of which global emissions are allocated to countries according to population only (C&C, LIMITS, Regensburg Formula, CDC). The Smooth Pathway Models in Chapter 3 calculates national paths starting from allocated remaining national budgets. The Emission Probability Model in Chapter 4 determines country specific emission density functions and caps the emissions of individuals.
- Mathematical Description of the Regensburg Model Scenario Types (RM 1 - 6)
  The Regensburg Model Scenario Types are used to derive plausible emission paths that meet a certain budget.

More downloads of this website

Own publications and discussion papers here
Tausendundeine Möglichkeit Treibhausgase einzusparen hier
Ziel - Mittel - Weg (Instrumentenvergleich auf einer Seite) hier