# Scenarios

## Business as usual

The business as usual (BAU) scenario does not contain any elements of climate policy. It does not follow a climate budget approach (cf. [Paris Agreement](https://etsap-tiam.readthedocs.io/en/latest/scenarios/paris-agreement.html)), or a CO2 price. The scenario primarily serves as a reference to climate policy in the scenario comparison in order to show the effects of climate policy.

## Paris Agreement

The Paris Agreement aims to limit global warming to well below 2 °C, preferably 1.5 °C compared to pre industrial levels [1]. To model this limitation a CO2 budget must be derived. This was done by the IPCC (c.f. Table 1) [2].

Table 1: Remaing CO2 Budget based on 1.5 °C and 2.°C scenarios 
|                                  | <  1. 5°C | < 2.0 °C |
|----------------------------------|-----------|----------|
| For a 66 % Change                |           |          |
| Carbon Budget (GTCO2) as of 2018 | 420,00    | 1.170,00 |
| For a 50 % Change                |           |          |
| Carbon Budget (GTCO2) as of 2018 | 580,00    | 1.500,00 |
| For a 33 % Change                |           |          |
| Carbon Budget (GTCO2) as of 2018 | 840,00    | 2.030,00 |


### References
[1]	United Nations, Framework Convention on Climate Change (COP21) Paris Agreement: Available online:. [Online]. Available: https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement (accessed: 22.01.23).

[2]	IPCC, “Mitigation Pathways Compatible with 1.5°C in the Context in the Context of Sustainable Development,” 2018.