At the risk of sounding rather arrogant, I find myself getting more and more frustrated by people justifying their position on the basis of a flawed understanding of the scientific evidence. One that seems particularly prevalent at the moment is the idea that cuts in CO2 emissions will have no effect for many decades. This has been used to argue that we should focus on developing resilience, and that reducing methane emissions is important if we want to stabilise the climate faster.
There are two problems I have with this narrative. Firstly, even if it would take many decades to feel the effects of CO2 emission reductions, that doesn’t mean that we shouldn’t be reducing these emissions now. CO2 accumulates in the atmosphere and how much we eventually warm depends on how much we eventually emit. If we don’t focus on CO2 emissions now, then either we’ll emit more than we otherwise could have (and will have to deal with the additional warming and resulting impacts) or we’ll have to make even more drastic emission cuts in the future. If the impact of these cuts would also not be felt for many decades, why would drastic emissions cuts in the future be more justified than doing so now?
The second problem I have is that it’s not actually correct. Recent work has demonstrated that peak warming from a pulse of CO2 emission occurs after about a decade. In fact, the paper that illustrates this, explicitly discusses the misconception that it would take many decades. So, if peak warming from a pulse of CO2 emission would take about a decade, the impact of emission cuts would also manifest on a similar timescale. In other words, the effects would be felt relatively quickly.
What’s important to recognise is that how much we warm in future depends mostly on how much we emit in the future. Since CO2 accumulates in the atmosphere, limiting how much we eventually warm depends primarily on limiting how much CO2 we emit. This doesn’t mean that we should not also focus on developing resilience and also aim to reduce emissions of short-lived greenhouse gases (like methane). However, we shouldn’t do so because we think CO2 emission cuts will have no short-term impact. Not only does this ignore that ultimately we need to limit the total amount of CO2 that we emit, it’s also wrong.