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Why the US can’t downgrade its Paris pledge for political convenience

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Will President Trump pull the US out of the Paris Agreement? Rumour suggests he will, and world leaders are reportedly engaged in last-ditch diplomacy to prevent this. It is not hard to imagine the damage that would be done to the carbon-cutting agreement by the withdrawal of the world’s second-largest carbon emitter.

US withdrawal appears a particularly unnecessary act of destruction to those who champion the flexibility built into the Paris Agreement. The Agreement is designed to weather the peaks and troughs of political commitment, over time and from country to country, while ensuring ambition ratchets inexorably upwards over time.

In this context, some are suggesting the US could simply downgrade its emissions reduction pledge, known as a Nationally Determined Contribution (NDC). Some such proponents may be wishing to offer the US a sweetener to stop it withdrawing altogether, although this would be at the expense of a greatly diminished conception of the Paris Agreement. Others may of course be perfectly happy to see the Paris Agreement watered-down.

Whatever the rationale for the argument, this reading of the Paris Agreement is mistaken.

To my mind, the Paris Agreement does not allow for back-sliding on ambition – not straightforwardly in any case; not as a Trump administration might be minded to pursue. This follows from an understanding of the Agreement as a whole, as well as from the language of the relevant article.

The importance of the ratchet

Article 31 of the 1969 Vienna Convention provides that treaties should be interpreted “in the light of [their] object and purpose”. To consider the Paris Agreement as a whole: it is impossible to overstate the centrality of the ratchet mechanism to the object of Paris. It is the ratchet that provides the means of bridging the gap between the pledges that we have now and the pledges that we will need in future to meet the Agreement’s temperature goals. It is the ratchet – established clearly by key provisions such as Article 3 and Article 4(3) – that underpins the Agreement’s most important objectives: providing a clear sense of direction and building momentum over time.

All of this cannot be short-circuited by an arguable interpretation of a single provision; Article 4(11).

Article 4(11) reads:

“A party may at any time adjust its existing NDC with a view to enhancing its level of ambition …“

The following arguments might be made in favour of an interpretation permitting back-sliding.


It may be argued that there are no penalties or sanctions that can be brought against a party for adjusting its carbon-cutting pledge downwards. But does this mean it is ‘non-binding’?

Talk of ‘bindingness’ in international law is something of a red herring. International law is ultimately voluntary and it binds parties only to the extent that the parties judge the benefits of compliance to outweigh the fallout of a breach. However, this calculation involves much more than the presence or absence of firm sanctions: breaching international law involves reputational damage as well as undermining of strength of international law more broadly, to the detriment of that country and others. Breaching the Paris Agreement carries an additional practical drawback, of course: greater likelihood of severe and destabilising climate change.

Woolly words?

The second argument is that the wording “with a view to” is soft language; that it doesn’t carry a positive obligation to achieve something. In fact it doesn’t carry any positive obligation at all.
The former point may well be true, but the latter, crucially, is not. This phrasing carries a positive obligation to hold a certain intention when an NDC is adjusted: to be acting in the service of enhancing overall long-term ambition. This common sense interpretation, from which there is no obvious reason to depart, accords with the treatment of “with a view to” in English law. Applied here, this would suggest that increasing ambition must be at least one of the purposes being served by any adjustment to an NDC.

The effect of Article 4(11) is therefore not to explicitly prohibit back-sliding, but nor simply to permit it. It says, in effect: “some backsliding can sometimes be permitted”. This is perfectly in keeping with the negotiating drafts of Article 4(11), which proposed various delimitations of the circumstances in which such adjustments could be made.

Article 4(11) keeps the door ajar for an NDC to be adjusted ‘sideways’ or even to edge downwards (remembering how difficult it can be to definitively say whether one NDC is more ambitious than another), provided that such adjustments are being made “with a view to” enhancing ambition.

To attempt an analogy: If the rules of football were more prescriptive they might read, “Players must kick the ball with a view to scoring in the opposing team’s goal”. Under such rules, players could shoot at goal, of course. They could certainly cross the ball from the wing into the opponents’ penalty area. They could even pass the ball backwards to their own goalkeeper, if in the circumstances that seemed the best or only chance, ultimately, of building an attack and scoring a goal. But some actions would nonetheless be positively prohibited. Kicking the ball into your own team’s net could not be an action taken “with a view” to scoring at the right end.The language is not precise, but it still has its limits.

The limits of flexibility

Back to the real world. How could an NDC be watered-down “in the view of” enhancing ambition overall? We might imagine a developing country temporarily unable to implement its NDC and opting to slacken the pace of emissions reductions for a time rather than pursue a course which would prove unsustainable and damage its capacity to achieve long-term progress.

We might imagine a developed country wishing to re-prioritise which sectors it intended to focus its efforts on, with the effect that progress over the short term might be dampened slightly, but deeper longer-term reductions made more cost-effective or technologically feasible.

On the other hand, certain downward adjustments will still be prohibited. We can imagine a country downgrading its ambition in order to generate jobs in the coal industry, or in order to send a message that it is sceptical of the cause of climate change. Such adjustments would not be “with a view to” enhancing ambition, and there is a clear obligation that they be so.

The practical question for many who value the Paris Agreement has become: What would be worse – an Agreement without the US, or an Agreement whose ratchet mechanism was watered down by an (in my view) unduly permissive interpretation of Article 4(11)?

It is hoped, of course, that the US will stay within Paris without downgrading its NDC. But if a weakened NDC is the price for keeping the US within the Agreement, the best response will be to understand that for what it is: a breach of the Paris Agreement.


This blog is an updated version of an article first published by Carbon Brief, under the title Can the US legally weaken its Paris Agreement climate pledge?. Lavanya Rajamani, professor of international environmental law, has since also published an analysis of this question, which is recommended and can be read here.

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A.C. Eggman