Earthquakes and climate change

I recently gave a talk for HSU’s Osher Lifelong Learning Institute (OLLI) about humancaused earthquakes. The talk focused mainly on earthquakes related to resource extraction and the filling of large reservoirs. Afterwards someone asked about climate change and if it could cause earthquakes. The short answer is no, but, as I think more about the question, it’s worth some clarification.

First, there is no doubt that climate change is real and human activity plays the major role. I’m not going to use this space to weigh the preponderance of evidence behind that statement. The question is whether increased sea levels, warmer waters or other consequences of climate change in any way affect the nature of earthquake activity on the planet.

Step one is to consider the cause of earthquakes. My OLLI talk was about human-caused seismic activity. My first point was that natural tectonic forces cause the overwhelming majority of earthquakes and all of the really large ones. I made a rough back-of-the-envelope calculation that perhaps 3% of the earthquakes in 2021 could be ascribed to a human cause.

Tectonic earthquakes are caused by the heat within the earth that drives plate motion. “Within the earth” is the crux of the matter. Earthquakes occur at miles beneath the surface in an environment where the thermal regime is entirely controlled by heat flowing upwards from the deeper parts of our planet. When people ask if there is such a thing as earthquake weather, I say of course just name it — snow, sleet, frost, rain, wind, drought, heat wave — are all earthquake weather. Earthquakes occur in every season, every time of day and under any weather condition. A one-, two- or even ten-degree change in average surface temperatures won’t make a bit of difference to earthquake generation.

But temperature is not the