My “why now” for climate

A thought experiment

My last post on climate explored why we should want to keep global warming within two degrees of the pre-industrial average. My “why now” could take a similarly clinical approach:

• To stay within the two-degree target, we need to limit greenhouse gas to ≈450 parts per million (PPM).
• To stay within our PPM target, we need to reduce global annual emissions from ≈55 gigatons of CO2 equivalents to net-zero by 2050.
• To hit net-zero by mid-century, we need to decarbonize every aspect of modern life as fast as we sensibly can.

But I can see that I’m already losing you.

Instead, let’s start with a thought experiment: imagine that we went net-zero tomorrow.

This would of course be cause for great celebration, but because planetary systems respond slowly, it wouldn’t be an immediate return to normal:

• Temperatures would continue to rise for years or even decades.
• Glaciers would continue to melt and sea levels would continue to rise, possibly for centuries.
• A child born today would reach middle age before seeing climate impacts begin to stabilize.

Here’s the point:

• Annual emissions only matter within the context of cumulative emissions.
• Every year of delay means more cumulative emissions.
• The higher the total, the worse peak impacts will be.
• The faster we cut emissions, the more we limit those impacts.

In other words, we can’t reverse course overnight, but we all help shape how much worse it gets and how soon things get better. Even modest steps can compound into better climate outcomes, and the faster we act, the greater the compounding benefit.

Do we have enough time?

The link between atmospheric carbon and global temperature was demonstrated before the first shots of the American Civil War, and we’ve had strong scientific argument for the link between human activity and climate change for as long as most Americans have been alive.

Despite overwhelming evidence, powerful forces in American life continue to delay structural change. Every year we wait makes the problem harder, more expensive, and more disruptive. 

One might understandably ask “do we still have enough time?”

This is the right sentiment, but the wrong question. The question we should be asking ourselves is “how much can we save?”

I find this framing helpful, as it’s similar to saving for retirement. Most of us wish that we’d started saving earlier, but we shouldn’t stop saving just because our target retirement date seems out of reach. We simply (re)commit to saving what we can, as quickly as we can.

It’s no different with climate: every step we take towards decarbonizing (where we get our electricity, how we get around, how we heat/cool our homes, etc.) reduces the peak warming that future generations will inherit; and the earlier the action, the more those actions buy us in terms of climate outcomes.

Who should lead?

Even among those who agree on the why and why now, the question of “who should lead/act?” is needlessly complicated, both by bad-faith actors seeking delay and good-faith actors seeking progress. I want to explore the question—and the debate behind it—in my next post.