Putting the brakes on climate change – it’s about more than just CO2

Climate change mitigation is about more than just CO2. Mitigating a suite of additional pollutants is important for limiting climate change: in particular, taking action on what are known as "short-lived climate-forcing pollutants" (SLCPs). Although it is common to report the effect of non-CO2 climate warmers in terms of "CO2 equivalence" they aren't simply "equivalent" – their effects on climate and ecosystem are distinct. In the case of SLCPs, one important difference is in the time horizon: SLCPs have the largest impact on near-term climate whereas CO2 has the largest impact on long-term climate. This article explores the reasons for these differences and examines why it is important to consider them when designing effective climate mitigation policies. It argues that clear communication on the different time horizons relevant for CO2 vs. SLCP mitigation is important for clarifying climate policy discussions and ethical decisions regarding the relative importance of near-term vs. long-term effects. It also argues that using a 100-year time horizon as primary basis for evaluating climate effects undervalues the positive near-term effects that can be achieved via SLCP mitigation –including for health, food security and sustainable development – and thus fails to take full advantage of near-term interests to motivate action.