What are realistic emissions targets for the world's six largest emitters that sum up to Paris-compatible emissions? To answer this question, this paper varies key framework data on the available global CO2 budget and the sharing mechanism to calculate top-down national emissions targets using the Extended Smooth Pathway Model (ESPM). The results will also be compared with the NDCs submitted by the six largest emitters. The Paris Ambition Mechanism is based on a bottom-up approach. However, if the national targets are not Paris-compatible in sum, the question arises whether national targets represent an adequate contribution to the necessary global efforts. An open and transparent discussion of this issue can contribute to NDCs that are Paris-compatible in sum. Here are a simplified web apps to reproduce the results: Paris-compatible national CO2 budgets: https://national-budgets.climate-calculator.info Emission paths that comply with a predetermined budget: https://paths.climate-calculator.info Implicit national CO2 budget derived from the NDC: https://ib-iwp.climate-calculator.info

In a future update, the Cement Carbonation Sink (CeCS) will be taken into account by correspondingly increasing the global CO2 budget used for the allocation. According to the GCP, CeCS currently amounts to around −0.8 Gt CO2 per year.