Nb. The differential in credits arises from using CDIAC’s figures for global production total as the basis for the first graphic, and global consumption total for the second. The concept of equitable shares of a carbon budget is the logical way to reflect equity and historical responsibility (as per the principles of the UNFCCC). However the concept is not directly established by the Paris Agreement, which imposes only the procedural requirement for countries to report their nationally determined contributions. If The Philippines is to pursue the full value of its ‘credits’ to other governments, it appears it will need to do so via a claim to the International Court of Justice. Assuming The Government of the Philippines were to bring an action against Party F, alleging its NDC is inconsistent with the objective of limiting warming to 1.5 or ‘well below’ 2 degrees Celsius, on what basis would the adequacy of Party F’s NDC be assessed?
UNFCCC directly incorporates a number of relevant principles of law, the most significant of which are:
 • • the precautionary principle (UNFCCC Art. 3(3)); and equity (UNFCCC Art. 3(1)). Likewise the Paris Agreement confirms that NDCs should be prepared on the basis of equity and common but differentiated responsibilities (Paris Agreement, Premable, and Article 4).
The question for the court might therefore be framed as follows:

In light of the precautionary principle, and principles of equity, is Party F’s NDC adequate to discharge its duty to prevent climate induced harm to The Philippines (and others)? One approach would be to begin with a conceptual distribution of the remaining budget on the basis of per capita shares (on the principle that no one person has a right to consume a greater share of the atmosphere’s storage capacity than any other). Dividing, let's say, 1000 Gigatonnes CO2 by a world population of 7.4 billion realises per capita shares of 135 tonnes CO2. That would give the US (with a population of about 320 million) a combined share of approximately 43.2 GtCO2. Bangladesh, with a population of about 160million would have approximately 21.6 GtCO2. According to US researchers Paul Murtaugh and Michael Schlax, the carbon legacy of the average female in Bangladesh is 136 tonnes (just a fraction over per capita shares of a 1000 Gt budget); while for the average female in the US the figure is 18,500 tonnes. Consequently a division of the budget on a per capita basis produces an equalising effect of 'contraction and convergence'.

There are two obvious objections to this approach, one likely to be raised by developing countries, the other by developed countries.

IPCC AR5 states that between 1750 and 2011 there were about 2000 Gt of cumulative anthropogenic CO2 emissions to the atmosphere (AR5, SPM 2.1). Developing countries might reasonably argue that an even distribution of the last third of the pie (after developing countries have consumed most of the first two thirds) fails to reflect historic responsibility. The principles of historic responsibility and ‘the right to sustainable development’ require the development of a formula for the notional 50