Chris writes: “There is tremendous interest at the moment in how emissions in non-CO2 gases can be reduced as a contribution towards constraining global warming. Peak levels of warming remain of particular concern, including whether we will remain below the often discussed threshold of two-degrees. Whilst any action on greenhouse gas emissions is of interest, what this paper finds is as follows. Reduction of short-lived gases as a mechanism to reduce peaks levels of global warming is most effective when CO2 emissions themselves are reducing significantly. Lowering methane emissions for instance (which has an atmospheric lifetime of around just 12 years) a long time before CO2-reductions are implemented is unnecessary - waiting until a time when CO2 emissions are also reducing will have the same effect on peak warming.
The argument implicit in this paper is that over the next few decades, in terms of reducing peak warming, the emphasis really should remain on tackling the longer-lived gases, and predominantly carbon dioxide, which by definition have a more cumulative effect on climate. Reductions in short-lived gases will be extremely useful too in restricting maximum warming, but working out how to reduce them can maybe wait temporarily, leaving mitigation policy to focus on carbon dioxide.”
You can read the paper on the Nature Climate Change website here.