Considering the role of SLCP (short-life climate pollutants, i.e. CH4, black carbon, tropospheric ozone and HFCs) in climate mitigation strategies, a recent academic study concluded that “Parallel strategies must focus on long- and short-lived pollutants, but not at the cost of reducing pressure for action on CO2.”
The study explains that focusing on these SCLPs could inhibit actions to slow the growth of fossil CO2 emissions, resulting in a higher peak temperature overall.
SLCPs have indeed an important climate impact, but as they persist in the atmosphere for only a short time—days to weeks for black carbon, a decade for CH4, and 14 years for the most prevalent HFC, HFC-134a, immediate reductions in SLCPs will result in relatively immediate climate benefits.
In contrast, CO2 has a very long atmospheric lifetime; more than 20% will remain for thousands to tens of thousands of years (note 1)
Initiatives for reducing SCLPs alone exist – for example HFCs can be regulated through the Montreal protocol – which would be able to slow the rate of warming in the first half of this century. But if such initiatives were to avoid international pressure to reduce CO2emissions, this would only trade the benefit for reducing SCLPs reduction for a steeper rise in temperature thereafter.
According to the authors, the only way to minimize the peak warming this century is to reduce in parallel the emissions of CO2 and of SLCPs. See the figure, which shows that the curve in red (CO2 and SCLP mitigation) gives the lowest temperature increase
This conclusion contradicts previous papers written by one of the co-authors (note 2), which restricted policies to mitigate climate change to SCLP or HFC reduction policies only.
EFCTC position : EFCTC supports an HFC phase down as prescribed by the forthcoming EU F-Gas Regulation Review, but reminds that reducing CO2 emissions by maintaining or improving energy efficiency should be required objective.