With the Paris Agreement, countries committed to collectively limit global warming to well below 2 °C and pursue efforts to limit warming to 1.5 °C above preindustrial levels. However, there is currently no commonly agreed effort-sharing mechanism to determine the contribution of each country. The Pledged Warming Map provides an assessment of global warming when all countries follow the ambition of a given one, reconciling the bottom-up architecture of the Paris Agreement with its top-down warming threshold.
The warming metric used in this website relies on a combination of equity concept where each country follows the least-stringent equity approach (from capability, historical responsibility or equality). This hybrid combination reflects the bottom-up pledge-and-review architecture of the Paris Agreement provides a warming assessment of countries’ NDCs. The results can inform the ratchetting-up process on the ambition of current emissions targets without hypothesizing an international agreement on a single approach of equity. The emissions trajectories can be used by experts and decision makers to derive emissions targets in line with the Paris Agreement mitigation goals.
This hybrid combination of countries’ least-stringent equity approaches is also relevant to climate cases where the court only rules for the least-ambitious end of an equity-based range.
The multiplicity of equity concepts results in a wide range of emissions allocations for countries and regions that is sometimes used as an uncertainty range by non-experts. In a recent climate case, the District Court of The Hague ruled that the Dutch government has to reduce 2020 emissions to at least the least-ambitious end of the range recommended by the IPCC-AR4 for the Annex I country group based on multiple equity allocations from 16 studies. The court did not pick an approach of equity and ruled for the minimum effort consistent with international treaties in light of commonly reviewed science.
While the multiplication of climate litigations cases against governments can contribute to the ratcheting-up process, systematic court decisions that governments must follow the least-ambitious end of an equity range would be insufficient to achieve the Paris Agreement. The trajectories presented here follow the least-stringent equity concept for each country individually but are collectively consistent with the Paris Agreement warming thresholds. Using the trajectories presented here to derive emissions target and phase-out dates enables to conform with the ambition of the Paris Agreement without selecting and applying a universal concept for all countries.
More information in the underlying peer-reviewed study.
Access here the Pledged Warming Map.