Web app Regensburg Model:
Calculation of Paris-compatible emission paths with converging per capita emissions

In the Regensburg Model, national emission paths are derived from a global emission path using the Regensburg Formula which leads to converging per capita emissions (see publications below).

In particular, the national CO2 budgets and the implicit weighting of the population (IWP) that result from the Regensburg Model provide valuable information for Paris-compatible targets.

In the Regensburg Model, six scenario types (RM 1 - 6) are offered to derive global emission paths that adhere to a predefined CO2 budget. These scenario types cover the range of plausible trajectories.

Important framework data that must be specified in the Regensburg Model (these can be freely set in the detailed Excel tool):

• Global CO2 budget 2020 - 2100 (information on this can be found here: http://ipcc-co2-budgets.climate-calculator.info)
  The app calculates the results for the following budgets:
  
  • 400 Gt,
  • 550 Gt or
  • 650 Gt.
• Separate CO2 budgets at global level 2020 - 2100 (reason: the emission data used for the countries does not include these emissions):
  • Land-use change (LUC; information on this can be found here: http://luc.climate-calculator.info)
    Assumption in the web app: -100 Gt
  • International shipping and aviation (ISA)
    Assumption in the web app: 3.2% of the global remaining budget (current share of global emissions)
• Potential for global net negative emissions and thus for a volume overshoot (information on this can be found here: http://luc.climate-calculator.info)
  Assumption in the web app: Minimum global CO2 emissions by 2100 -3.7 Gt (-10% of global emissions in 2019)
• Convergence level: global per capita emissions, where convergence is to take place. The web app uses the population figures from 2019.
  You can specify the convergence level in the web app.

When you select a country, you can see the resulting emission paths, reference values and other key figures.

In the corresponding sheets you can see the underlayed global paths and the corresponding national CO2 budgets for all countries in the world.

Global budget 400 Gt:

Global budget 550 Gt:

Global budget 650 Gt:

Notes:

• The emission paths cover CO2 emissions from fossil fuel use (excluding international shipping and aviation; ISA) and cement production. ISA and land-use change (LUC) are therefore not covered. Budgets are reserved for these two fractions at the global level (see this paper on the LUC budget).
• As a budget of zero Gt was set for LUC for the period 2020 - 2100, corresponding net negative CO2 emissions must be achieved in the LUC sector in order to offset any net positive CO2 emissions in this area.
• CO2 neutrality must be achieved before climate neutrality, as net negative CO2 emissions are required to offset, for example, unavoidable methane and nitrous oxide emissions from agriculture. These net negative CO2 emissions must be provided in addition to the net negative CO2 emissions (overshoot) shown here.
• Since the focus here is on what national CO2 budgets would result for the countries in the event of converging per capita emissions and a distribution of a global CO2 budget from 2020 on, actual emissions after 2019 are not taken into account in the emission paths.

The most important result of the Regensburg Model

An important indicator in the Regensburg Model is the implicit weighting of the population (IWP), which is the same for all countries depending on the scenario type chosen for the global path and the convergence level chosen. The IWP is basically independent of the selected global budget (remark: there may be slight deviations, as the actual convergence level - indicated in the app - may differ slightly). The respective IWP is specified for each scenario type in the app. In general, the more ambitious the global path at the beginning, the higher the IWP.

More information on IWP can be found here.

The corresponding sheet shows the national CO2 budgets resulting from the IWP for all countries in the world.

Our web app http://national-budgets.climate-calculator.info can be used to determine Paris-compatible national CO2 budgets for all countries in the world, based on an explicit weighting of the population.

Detailed Excel tool

You can download the detailed Excel tool at: https://doi.org/10.5281/zenodo.5846043.

Some publications on the Regensburg Model

► The Regensburg Model: reference values for the (I)NDCs based on converging per capita emissions, journal 'climate policy', ; published 2016
► Calculation of Paris-compatible emission targets for the six largest emitters with the Regensburg Model, ; published on Zenodo
► Distribution of a Global CO2 Budget - A Comparison of Resource Sharing Models, ; published on Zenodo

Global remaing CO2 budgets

Here are key statements by the IPCC on remaining global CO2 budgets.

Main page

www.save-the-climate.info