Global climate negotiations often focus on where we end up, for example, the 1.5°C target set by the Paris agreement. But there’s a crucial detail hiding in plain sight: how quickly we reduce warming on the way to that target can dramatically reduce the incidence of climate impacts on the global poor. Our new analysis puts numbers on that intuition by tracking the effect of climate change on a most personal outcome: human lives. Sustained cuts to methane emissions starting today saves many more lives compared to delaying action — and those lives are disproportionately in the places most vulnerable to climate change.

The same 2100 temperature, very different human outcomes

We compare six mitigation pathways — avoiding methane (CH₄) and carbon dioxide (CO₂) emissions, each implemented rapidly, slowly, or with a delayed start — designed so they all reach the same global temperature outcome in 2100. This matters because it isolates something policy debates often gloss over: timing. If two strategies hit the same end-of-century target, it’s tempting to treat them as roughly equivalent, particularly if one of them delays costly mitigation. Figure 1 shows warming under business as usual, and two of these scenarios: rapid methane mitigation and delayed CO₂ mitigation.