My PhD thesis was really focused on natural climate variability, not on climate change. Climate change really wasn’t even on my radar screen as I was starting my thesis. As that work progressed, it led us in the direction of using archives of the distant climate past, known as proxy records: the tree rings, corals, ice cores. We can only go back in time about a century and a half with the instrumental climate records. I got interested in what those proxy records could tell us about long-term natural cycles.
It was the process of using those data and using them to reconstruct the past climate that produced this curve known as the hockey stick curve, which shows the abrupt warming of the past century to be without precedent as far back as we were able to go, 1000 years, in our original publication two decades ago.
We published that graph in the late 1990s, when the debate over climate change was really coming to a crescendo. While the scientific evidence was mounting, fossil fuel interests were increasingly using their tremendous financial resources and power to attack the science.