From the start of the COVID-19 pandemic, public health officials urged us to “flatten the curve,” to wear masks and observe social distancing to slow the rate of infection. Spreading out cases over time prevented healthcare resources from being overwhelmed and thereby improved survival rates. With a flatter, longer curve, the cumulative number of infections may have ultimately ended up the same, but the peak number of active cases—and thus the total number of deaths—was likely reduced. Although the pandemic is far from over, early efforts to flatten the curve saved lives and bought critical time to develop therapies and vaccines.

Several authors have commented on the parallels between the pandemic and climate change, noting that the buildup of greenhouse gases in the atmosphere—and the corresponding increase in global temperatures—is another curve that desperately needs flattening. The comparison is apt: in both cases, science-based policy and decisive collective action are keys to averting disaster. There’s another, more subtle lesson in efforts to flatten the pandemic curve: It’s not just the endpoint of a trajectory that matters; the path we take to get there plays a key role in shaping outcomes.

The endpoint for many climate projections is the year 2100. The amount of warming the Earth experiences by that time will be determined, in large part, by our success in curbing carbon dioxide (CO2) emissions. On a per-kilo basis, CO2 is a fairly weak greenhouse gas. But it is emitted in huge quantities by human activities, primarily the burning of fossil fuels. Since the start of the Industrial Revolution, atmospheric concentrations of CO2 have increased from less than 280 parts per million (ppm) to more than 415 ppm. During that same period, global temperatures have increased by about 1.0°C; of this, a little more…