Looking at the Planetary Past to Prepare for Our Climate Changed Future—An Interview with Steven Earle

In preparation for writing a recent article on climate change, I read two books by Steven Earle, Runaway Climate and A Brief History of Earth’s Climate. I was impressed by the clarity with which Dr. Earle is able to convey the complexities of climate science to lay readers. Rather than trying to summarize his books for my readers, I thought it would be better to invite Dr. Earle to do so in his own words. I contacted him through our mutual publisher, and he generously agreed to an email interview.

In addition to the two books mentioned above, Steven Earle is the author of two Earth science textbooks (Physical Geology and Environmental Geology) and conducts research into the impacts of climate change in the area around Vancouver Island. He has been involved in post-secondary Earth science education for over four decades, and that includes developing and teaching courses on environmental geology, glacial geology, and climate change. He is also active in climate change issues in his local community, including development of local low-carbon transit options, creation of active-transportation infrastructure, stewardship of land for affordable housing and local food production, and marching the streets with signs and noise makers.

RH: Thanks, Dr. Earle, for agreeing to this interview. Your book Runaway Climate deserves wide readership—though it’s largely about something most people have never heard of, the Paleocene Eocene Thermal Maximum, or PETM. How was this event in Earth history similar to what’s happening now with our current bout of climate change?

SE: The PETM was an abrupt climate event that happened at the boundary between the Paleocene and Eocene Epochs, 56 million years ago. The climate changed quickly because of runaway feedbacks, but it had to start with some kind of trigger event. What we are doing to our climate today—mostly by emitting massive amounts of greenhouse gases—might be equivalent to the triggering event that happened back then. If we are not careful, we can expect to start seeing runaway feedbacks that could soon take us into a very different and dangerous climate situation. There are multiple reasons to think that feedbacks are just as likely to take effect now as they did back then. In fact, there is more potential for runaway feedbacks now because of the massive amount of glacial ice and sea ice on Earth today, and our rapid rate of GHG emissions.

RH: What caused the PETM?