Another momentous step?

Following the ICAO deal to offset the global growth in aviation emissions and the Paris Agreement passing the 55 / 55 criteria for entry into force, a third major announcement has followed in as many weeks; the agreement of an addendum to the Montreal Protocol (agreed in 1987 to progressively eliminate the use of chlorinated fluorocarbons or CFCs, coming into force in 1989) which will bring the HFC family of gases into that process, leading to their eventual elimination from day to day use.

Hydrofluorocarbons or ‘HFCs’ have been increasingly used this century as an alternative to ozone damaging CFCs in refrigeration systems. Though HFCs provide an effective alternative to CFCs, they are also powerful greenhouse gases. A snapshot of current greenhouse gas emissions to atmosphere highlights the HFC issue; today they represent approximately 1 Gt on a CO₂ equivalent basis, or about 2% of the total GHG problem.

While 2% is not insignificant, being just above the impact that aviation currently has on the climate issue, it is the longer term impact that the growth in use of these products has that is the main cause for concern. India alone could build upwards of 400 million refrigerators over the coming 20 years. But following seven years of negotiations, the 197 Montreal Protocol parties reached a compromise, under which developed countries will start to phase down HFCs by 2019. Developing countries will follow with a partial freeze of HFCs consumption levels in 2024, with some countries freezing consumption in 2028. By the late 2040s, all countries are expected to consume no more than 15-20 per cent of their respective baselines. A small group of countries is treated more leniently owing to the very high local temperatures experienced during much of the year.

This is an important agreement, but I certainly didn’t expect to see the claim that came from UNEP (United Nations Environmental Programme) that the Kigali Amendment to the Montreal Protocol (as this was agreed at the 28^th Meeting of the Parties to the Montreal Protocol at their meeting in Kigali, Rwanda) was the equivalent of shaving 0.5°C from the anticipated warming of the climate system. Secretary of State John Kerry rounded this up slightly and referred to the result as a 1°F achievement. The claim was reminiscent of the pre-Paris statement by the UNFCCC that the INDCs submitted had already reduced warming to 2.7°C, a story that carried right through the December COP and gave great confidence to the negotiators. Such a number could be arrived at with some big assumptions about the future but most commentators put the level of warming after the INDCs (and assuming they are delivered) at something around 3.8°C (which was at least less than 4+°C).

The source of the 0.5°C figure is a series of academic papers, such as a 2013 paper from Scripps Institution of Oceanography (The role of HFCs in mitigating 21st century climate change, Y. Xu1, D. Zaelke, G. J. M. Velders, and V. Ramanathan). This paper notes that most HFCs now in use have relatively short lifetimes in the atmosphere in comparison with long-lived GHGs, such as CO2 and N2O (nitrous oxide) and are therefore referred to as short-lived climate pollutants (SLCPs). The global average lifetime, weighted by the production of the various HFCs now in commercial use, is about 15 years, with a range of 1 to 50 years. But the chemicals have very high global warming potentials (e.g. over 4000 for HFC-143a).

Therefore, HFCs have a significant impact on radiative forcing in the years immediately after release into the atmosphere, but their impact on peak warming when that occurs depends more on the level of HFC emissions at that time rather than the emissions now or in the near term. As such, the warming that they induce is nearer term and tends to mean that we will reach a certain temperature earlier than we might have, even if the eventual peak warming remains the same. Peak warming is dictated primarily by cumulative CO2 emissions, with the approximate relationship of 2°C for every trillion tonnes of carbon (or 3.7 trillion tonnes CO2) emitted.

Nevertheless, some significant warming numbers arise, although they are very dependent on the HFC demand projections and scenarios that are developed. Mitigation of the potential growth of HFCs is shown to play a significant role in limiting the warming to below 2°C this century and could contribute additional avoided warming of as much as 0.5°C by 2100. Using the lower limits of BAU increase of HFC, 0.35°C warming is shown to be avoided.

Most importantly though, this paper emphasizes that HFC mitigation should not be viewed as an “alternative” strategy for avoiding the 2°C peak warming, but rather as a critical component of a strategy that also requires mitigation of CO2 and the other SLCPs. The focus of the study presented was on near-term warming over the next several decades to end of the century. For the longer-term (century and beyond), mitigation of CO2 would be essential for a significant reduction in the warming.

A further feature of the Kigali Amendment was an agreement to provide adequate financing for HFCs reduction, the cost of which is estimated at billions of dollars globally. The exact amount of additional funding will be agreed at the next Meeting of the Parties in Montreal, in 2017. Grants for research and development of affordable alternatives to hydrofluorocarbons will be the most immediate priority. But this financing requirement may still cause problems, particularly if the US Senate requires oversight of the amendment, given it ratified the Montreal Protocol in the first place. With the ink barely dry on the Kigali documents, The Guardian was already reporting that in the view of some legal experts the US Senate will have to vote on the issue.