With the Paris Agreement, countries agreed to limit global warming to well below 2 °C and pursue efforts to 1.5 °C. Equitable distribution across countries of emissions rights consistent with these goals is contentious and involves divergent views of distributive justice. With the absence of consensus on an equitable effort-sharing approach, current negotiations under the UNFCCC follow an uncoordinated, or ‘bottom-up’, approach where each country tends to support its favoured approach of equity. The sum of all parties’ announced contributions is not consistent with the Paris Agreement mitigation goals. Firstly, this talk reviews the challenges of quantifying equitable effort-sharing approaches to derive national emissions trajectories consistent with the 2°C and 1.5°C goals. Secondly, a novel self-differentiated, or ‘bottom-up’, attribution of equity approaches consistent with the ‘top-down’ global Paris Agreement goals is introduced. This novel ‘hybrid’ combination of equity approaches provides a temperature scale inclusive of all national positions, to assess the ambition of the Nationally Determined Contributions to the Paris Agreement.