Greenhouse gases to be covered under Paris Agreement and Montreal Protocol

Legal assistance paper

All reasonable efforts have been made to ensure the accuracy of this information at the time the advice was produced (please refer to the date produced below). However, the materials have been prepared for informational purposes only and may have been superseded by more recent developments. They do not constitute formal legal advice or create a lawyer-client relationship. You should seek legal advice to take account of your own interests. To the extent permitted any liability is excluded. Those consulting the database may wish to contact LRI for clarifications and an updated analysis.

Date produced: 15/09/2015

1) What greenhouse gases will be covered in the new climate agreement ? will they be all the gases not addressed under the Montreal Protocol or some only? What guidance and information is there on this issue ?

2) Please can you clarify the relationship between the UNFCCC and the Montreal Protocol.


The UNFCCC provided a general, inclusive definition of “greenhouse gases”,  but in practice gases controlled by the Montreal Protocol were excluded from the scope of its obligations.  The Kyoto Protocol was even more restrictive, only covering listed gases.  These included HFCs and PFCs, which are recommended as non-ozone depleting alternatives by the Montreal Protocol’s Technology and Economic Assessment Panel, but unfortunately have high global warming potential. My view is that it would be difficult to try and advocate for  regulation of HFCs and PFCs under the Montreal Protocol, since they do not have ozone-depleting properties and are thus not covered by the objectives of the Vienna Convention for the Protection of the Ozone Layer or the Montreal Protocol.

At this stage, the publicly available draft negotiating texts for the Paris Agreement suggest that its obligations will be applicable to all GHGs.  No definition of GHG is provided, and there is no express carve-out for gases controlled by the Montreal Protocol.  Of course, those gases that are already virtually eliminated by virtue of the Montreal Protocol will remain banned under that Protocol.  It is only the global-warming potential of ozone-depleting gases that are not yet (fully) banned that will be the subject of regulation under the Paris Agreement as well.  As most of the obligations are expressed at a general level, rather than at the level of industry or particular gases, it is unlikely to be the subject of express focus within the negotiations.


I understand that this query relates to the scope of the climate change agreement that will be negotiated at the COP 21, in particular, whether it covers greenhouses gases [GHGs] already governed by the Montreal Protocol.  I will answer this query in two parts, first looking at the historical relationship at a fairly technical level on the basis of what GHGs are and are not covered by each of the relevant agreements.  I will then examine the current publicly available documents as to what the likely scope of the Paris Agreement will be in this regard.

Relationship between UNFCCC and Montreal Protocol

Scope of the UNFCCC

The 2006 UNFCCC Handbook and the 2006 Handbook for the Montreal Protocol may be helpful resources for a general overview.

While the UNFCCC includes in its definitions gases that are also governed by the Montreal Convention, the scope of its substantive obligations are restricted to exclude such gases.  The definition of “greenhouse gases” in art 1 of the UNFCCC is: “those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and re-emit infrared radiation.”  Moreover the word “emissions” covers the release of all greenhouse gases and their precursors.  However, if one examines article 4, which sets out the “Commitments”, the phrase “greenhouse gases not controlled by the Montreal Protocol” is used instead.  Thus for instance, the obligation to publish and make available national inventories of anthropogenic emissions does not apply for greenhouse gases controlled by the Montreal Protocol.

On the other hand, certain aspects of the UNFCCC are expressed to cover gases also controlled by the Montreal Protocol.  Namely, greenhouse gases covered by the Montreal Protocol would be excluded unless expressly excluded with the words “not controlled by the Montreal Protocol.” The Preambular, Objectives and Principles section all refer to “greenhouse gases” without restriction. In particular, Article 2 is important as it has guided the course of the negotiations since the UNFCCC, and I set it out in full:

Article 2


The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.”

That is, the ultimate objective of the UNFCCC and related legal instruments adopted by the CoP is to stabilise all greenhouse gas concentrations, which includes GHGs controlled by the Montreal Protocol.

Scope of the Kyoto Protocol

The Kyoto Protocol was a Protocol to the UNFCCC and is thus to be interpreted in light of the UNFCCC. However, unlike the UNFCCC, which did not specify the GHGs that were covered by it, the Kyoto Protocol provided a list of GHGs in Annex A.  That list was last revised in Doha in 2012.  Both HFCs and PFCs are listed as “greenhouse gases”.  Despite this list, some aspects of the Kyoto Protocol are broader, and refer more generally to GHGs.  In fact, three different formulations are used to refer to GHGs.  The first is simply an unqualified reference to “greenhouse gas emissions”. Other obligations use the UNFCCC formulation of “greenhouse gases not controlled by the Montreal Protocol”.  However the most common formulation, and the one used for most of the concrete obligations, is to refer to those GHGs listed in Annex A.  For instance, art 3(1) requires that the Parties in Annex I reduce their “aggregate anthropogenic carbon dioxide equivalent emissions of greenhouse gases listed in Annex A” by a certain formula.  Essentially, this last is the most restrictive way of referencing GHGs.  Seven GHGs are currently listed in Annex A: CO2, CH4, N20, HFCs, PFCs and SF6, with the most recent, NF3, having been added as part of the Doha Amendments in 2012.  Thus not only was every gas covered by the Montreal Protocol excluded from most substantive obligations in the Kyoto Protocol, but so were any other gases that had (or might be discovered to have) global warming potential, but were not listed in Annex A.  There is no obligation targeting the reductions of HFCs and PFCs in the Kyoto Protocol. Rather, GHGs listed in Annex A are treated as an aggregate group, such that it would be possible for a country to meet its reduction obligations by reducing CO2 emissions without focusing on other gases.

Scope of the Montreal Protocol

The ozone-depleting gases covered by the Montreal Protocol are set out in Annexes A-E of that Protocol, as updated.  Article 1 states that these substances are covered, “whether existing alone or in a mixture”, except those that are already a component of another manufactured product.  Certain products are now also covered. Refer to the annexes for an exact list, but essentially the following substances are covered: CFCs, halons, other fully halogenated CFCs, carbon tetrachloride, methyl chloroform, hydrochlorofluorocarbons (HCFCs), hydrobromofluorocarbons (HBFCs), methyl bromide and bromochloromethane.

Under the Montreal Protocol, CFCs were phased out and replaced with HCFCs on an interim basis, which have a much lower ozone depleting value in the short-term.  In turn, with minute exceptions, these must be phased out by 1 January 2020.  These are being replaced by hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs), which have no ozone depletion potential, on the recommendation of the Technology and Economic Assessment Panel.  These alternatives are unfortunately recognised as having high global warming potential.  Although HFCs and PFCs are greenhouse gases, they are not “controlled by the Montreal Protocol” because they do not have ozone depleting effects.

Overview of the relationship

My understanding of the historic relationship between the UNFCCC and the Montreal Protocol is that the obligations in the former mainly regulated gases that did not have ozone-depleting qualities, even if they also had global warming potential; while the latter only regulated gases with ozone-depleting qualities.  The result of this over-lap was that many gases with significant global warming potential have been eliminated, due to the success of the Montreal Protocol.  On the other hand, it is regrettable that certain gases with high global warming potential are proposed under the Montreal Protocol as alternatives to ozone-depleting gases banned under the Protocol.

I note that EIA has dealt with the relationship between the UNFCCC framework and the Montreal Protocol in a 2012 position paper about HFCs.  That paper argued that:

Under the Vienna Convention, the Montreal Protocol has been tasked with responsibility for controlling ODS and dealing with any “adverse effects” arising from their elimination. Without question, the negative impact and contribution to global warming arising from using HFCs as alternatives to ODS qualifies as an “adverse effect” that is a direct result of the ODS phase-outs, and as such it is time for the Montreal Protocol to fully embrace its obligations and act decisively to regulate HFCs. The recovery of the ozone layer will be a hollow victory indeed if it is eclipsed by the multiple, far-reaching and catastrophic impacts of acute climate change. The Montreal Protocol must act.

I understand that EIA may wish to argue for this position from a political view – in light of the effectiveness of the Montreal Protocol system, it may seem a more effective forum to get HFCs (and PFCs) phased out than the UNFCCC system.

From a legal perspective, however, I disagree with the analysis in this paper to the extent that it suggests that the phase-out of HFCs falls within the current mandate of the Vienna Convention/Montreal Protocol.  In particular, it should be noted that the words “adverse effects” are not used in the way that this paper alleges.  The Preamble of the Vienna Convention notes the determination of the Parties to the Convention: “… to protect human health and the environment against adverse effects resulting from modifications of the ozone layer”.  That is, the only adverse effects falling within the scope of the Convention are those arising from modifications of the ozone layer.

The Montreal Protocol then implements the Convention and adopts the same focus:

Being Parties to the Vienna Convention for the Protection of the Ozone Layer,

Mindful of their obligation under that Convention to take appropriate measures to protect human health and the environment against adverse effects resulting or likely to result from human activities which modify or are likely to modify the ozone layer,

Recognizing that world-wide emissions of certain substances can significantly deplete and otherwise modify the ozone layer in a manner that is likely to result in adverse effects on human health and the environment,

The Preamble also recognises “the potential climatic effects of emissions”, but it is clear that the scope of the Protocol is to deal only with substances that can deplete or modify the ozone layer.

There may be strong legal and political objections to inserting HFCs or PFCs into the Montreal Protocol. It is able to be amended, but it would cut against the whole scheme of the Protocol and Vienna Convention for non-ozone depleting gases to be regulated under its mandate. Moreover, it is also not clear whether the Protocol can be amended in a way that goes beyond the original objectives of the Vienna Convention, and whether the Vienna Convention would also have to be amended. The relationship between the two is not straight-forward. The Montreal Protocol refers back to the Vienna Convention in its Preamble, and also reaffirms its aims to reduce world-wide emissions of substances that can deplete and modify the ozone layer.  If the Convention would also have to be amended, this makes the chances of success more difficult, since a 3/4 majority is required for an amendment to the Convention, as opposed to a 2/3 majority is required for an amendment to the Protocol. Co-ordinating an amendment to both the Vienna Convention and the Protocol would also be administratively difficult.

Thus, in my view, it would be better to focus on the Climate Change negotiations in advocating for the potential phase out of HFCs and PFCs.

COP 21: Paris negotiations

The question is what gases will be on the table at the Paris negotiations.  It will be possible to get a clearer picture on this once the Draft Agreement is released in October for the ADP 2.11.  I am not currently aware of a proposed “definition” text for “greenhouse gases” that directly answers this question.  However, looking back across the negotiations thus far, under the track agreed at the Warsaw COP19 in 2013, the language used in most of the negotiation documents speaks generally of greenhouse gases, providing no carve-outs.

The only current draft text is the Geneva Negotiating Text.  A “non-paper” consolidated text was issued at ADP 2.9 in June 2015, and then updated the 24 July 2015, the latter of which will likely guide the negotiations.  There are no material differences in these three documents. They all refer to greenhouse gases generally, without defining “greenhouse gases”. The definitions section is not yet complete but does not currently provide “greenhouse gases” as one of the terms for which a definition will be negotiated. The draft text frequently references “greenhouse gas emissions” or “global greenhouse gas emissions”, or “net zero greenhouse gas emissions”.  The concrete obligations in the Convention are expressed in terms of “global greenhouse gas emissions”.

This terminology takes on particular significance when seen in the context of the earlier climate change agreements.  Both the UNFCCC and the Kyoto Protocol used more restrictive terms to refer to the GHG emissions that were covered by their obligations, including the term “greenhouse gases listed in Annex A” in the case of the Kyoto Protocol.  There is no such limiting Annex in the current draft Paris Agreement.  Neither is the relationship between the new Paris Agreement and the Montreal Protocol explicitly addressed. The Montreal Protocol is referred to twice, in relation to promoting technology to reduce GHG emissions not controlled by the Montreal Protocol, and dealing sustainably with sinks and reservoirs of GHG not controlled by the Montreal Protocol.  But there is no otherwise no carve-out for the Montreal Protocol or for ozone-depleting gases controlled by the Montreal Protocol.  The words “greenhouse gases controlled by the Montreal Protocol”, which were so prevalent in the UNFCCC, do not appear in relation to any of the principal obligations.

It is legitimate to look to these texts as part of the relevant interpretative context, whether under art 31(2) or art 31(3)(c) of the Vienna Convention on the Law of Treaties.  However, they may also be specifically invoked in the end Paris Agreement.

On a straight-forward textual interpretation, and on a contextual interpretation, all greenhouse gases would be expected to be included, with two minor exceptions where a carve-out is retained for gases covered by the Montreal Protocol. At the moment the approach being taken is focused on net emissions, rather than on sector or gas-specific emissions, so there is no targeting or listing of particular gases.

The question of whether all GHGs will ultimately be covered by the Paris Agreement is ultimately a political one, and those closer to the negotiations may have a more accurate answer from a political point.  However, from a legal perspective, based on an analysis of the publicly available documents, and in light of the historical relationship between the climate change treaties and the Montreal Protocol, it seems likely that all greenhouse gases will be covered by the main obligations in the Paris Agreement, including all the gases covered by the Montreal Protocol with global warming potential, with the two exceptions noted.  In practice, however, many of these gases will already have been phased out, or be significantly phased out, by the time the Paris Agreement is signed.

In my view, it would be helpful to push for a definition of “greenhouse gases” in the Paris Agreement (which may simply adopt the definition in the UNFCCC) and for a specific clause that deals with the interaction with the Montreal Protocol.  Although the position is fairly clear under the current draft that all GHGs are included, some ambiguity is created by the historic fact that ozone-depleting gases were excluded from the scope of the climate change agreements.  It may also be helpful to clarify the interactions between the Secretariats and provide for greater co-ordination, so that, in future, replacement substances with high global warming potential are not recommended as replacements for substances banned under the Montreal Protocol.

Within the Montreal Protocol, rather than pushing for an amendment to phase-out HFCs and PFCs, it may be more productive to pick up on the Preambular language recognising the issue of global warming, and instead push for an amendment that requires that the global warming potential of any possible replacements be taken into account in recommending their use.