Some climate damage is now unavoidable even if we clean up our act
With the world looking likely to exceed 1.5°C of warming, the plan is now to reduce our carbon emissions after overshooting the target. What lasting damage will this have?
Thermometers, at least traditionally, don’t remember. Mercury expands in response to heat energy, and the red line rises. The temperature falls, the mercury contracts, the line descends. Yesterday’s measurement has no bearing on today’s.
But even if thermometers can’t measure it, rising temperatures leave a lasting mark. Forests die, ice sheets melt and species go extinct. Now that the world is within touching distance of 1.5°C of warming, we are getting hints of the climate chaos we can expect over the coming century. So how bad will it be, and is the damage reversible?
This isn’t just an abstract question. Last month, the United Nations finally acknowledged that holding warming to 1.5°C above pre-industrial levels would only be possible if Earth overshoots that threshold, then cools back down by 2100. “Overshoot, peak, decline” is the new mantra for decision-makers. Let’s put aside, for the moment, the rather large question of how global cooling on this scale could be delivered. What lasting damage do we risk by overshooting? It is a question scientists are racing to answer.
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There is some good news. Important land carbon sinks like the Amazon rainforest seem to be able to bounce back from short-term climate shocks. We may even be able to resuscitate the AMOC, a vital ocean current, after a climate-induced collapse – although it won’t be easy.
When it comes to sea-level rise, we have locked ourselves in for a lot of future pain
But the bad news is that some climate impacts are locked in, even if we clean up our act immediately. As we report, Thwaites glacier in Antarctica looks to be beyond saving, even if ocean-driven melting were halted overnight. In short, when it comes to sea-level rise, we have locked ourselves in for a lot of future pain.
That isn’t a reason for despair. Once we pass 1.5°C of warming, we should double down on cutting emissions, not give up. But we should be aware that, even if we do successfully deliver global cooling, we won’t emerge from the overshoot years unscathed. What we do today matters for tomorrow.
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