The Kigali Amendment on hydrofluorocarbons (HFCs) is excellent news for the climate. It tackles a powerful greenhouse gas, binds parties to take action with more teeth than the Paris Agreement, and demonstrates again our international capacity to cooperate.
However, the climate change benefits are unlikely to supplement those of the Paris Agreement and deliver the widely reported “high hopes” of an additional 0.5°C of avoided warming.
Here’s the source of the high hopes. Many have cited one study that estimates that HFCs could increase temperature change by as much as 0.5°C. So, as many have asked us here at Climate Interactive, can we now revise the temperature estimates resulting from the Paris Agreement?
No, we cannot, unfortunately. The Kigali amendment will not lead us to revise our estimate of expected temperature increase in the Climate Scoreboard – 3.5°C – down to a lower temperature (for example, to 3.0°C after a 0.5°C reduction.)
There are two main reasons:
- Lack of additionality. Actions to reduce HFCs were already included in many national contributions (INDCs) from major emitters to the Paris Agreement, so have in part already been accounted for in temperature assessments. The U.S., for example, plans to meet its INDC of 26-28% below 2005 levels by 2025 by taking federal action on HFCs. The U.S. INDC includes all greenhouse gases, including HFCs, and among the actions the U.S. is taking to meet its INDCs it details that “the United States Environmental Protection Agency is moving to reduce the use and emissions of high-GWP HFCs.” And the EU, in its biennial report to the UNFCCC has also explained that they are reducing HFC emissions as part of actions to fulfill its INDC.
- Estimate of temperature impact outside the bounds of IPCC studies. The idea that reducing HFCs could have 0.5°C of temperature impact comes from research by Xu et al. Their analysis stands apart from current IPCC estimates in that they assume a much higher contribution from HFCs to warming than the IPCC, and, thus, a much larger potential for reductions. The Xu et al. analysis assumes that, if we take no action, radiative forcing from HFCs would be over four times as much as the highest-emissions IPCC scenario (RCP 8.5, see figure 1). They estimate that net radiative forcing from HFCs by 2100 would be ~.68 w/m2 (mid point of ~.84 at the high and ~.53 at the low) whereas RCP 8.5 estimates ~.15 w/m2.
Put another way, because we have calibrated our simulation model, C-ROADS, against the IPCC RCP 8.5 scenario, there is not 0.5°C of warming to avoid with mitigation policies.
Figure 1: Diagram from the Xu et al. paper. Notes with arrows to the right added by Climate Interactive.
So here is where we stand. Without the actions from the Paris Agreement, countries would be on course for 4.5°C, but if countries fully implement their pledges so far to the Paris Agreement – and the Kigali Amendment will help — we will reduce expected warming to 3.5°C. This is still far from the Paris goal of limiting warming to 1.5°C.
Indeed, a recent article by John Vidal in the Guardian said it well: “The deal keeps the Paris agreement on track.” And Climate Analytics, who contributes to another temperature assessment of the pledges to the Paris Agreement, makes a similar point.
The Kigali Amendment is important, but is no silver bullet. Instead, it is one part of the “silver buckshot” that, little by little, will help create the climate results we all want to see.
— Andrew Jones and Ellie Johnston