There are climate scientists all over social media highlighting how staggering September 2023’s global surface temperature anomaly has been. It’s about 1.75oC above the pre-industrial reference period. This is in addition to Antarctic sea ice also “dropping off a cliff” in 2023.
This could all just be internal variability on top of an anthropogenically-driven trend. A strong El Niño is developing and there are potential reductions in anthropogenic aerosol emissions. Both of these could, for example, have contributed to the unusual increase September 2023’s unusually large increase in global surface temperature anomaly.
However, this does illustrate a concern I have always had about climate change. We do have a pretty good understanding of the climate system, both from recent observations, paleo-climatology, and very sophisticated climate models. However, we are perturbing a complex, non-linear system in a way that is reasonably unprecedented. Even though we might have a good understanding of how it’s likely to respond, it could still respond in unexpected ways.
Of course, what we’re seeing now doesn’t necessarily indicate that we’re seeing responses that are outside what we’d expect, but they are still rather surprising and not exactly comforting.
Of course, none of this really changes what should probably be done. Stopping anthropogenically-driven climate change is going to require getting anthropogenic emissions to (net) zero, and dealing with the impacts that we can’t, or probably won’t, avoid is going to require developing resilience and reducing vulnerabilities. We just shouldn’t ignore that the climate can respond to anthopogenic forcings in ways that, even if not completely imexpected, are still surprising.