Abstract: Fingerprint research seeks to improve understanding of the nature and causes of climate change. The basic strategy is to search in observed climate records for the patterns of climate change (the “fingerprints”) predicted by a computer model. Fingerprint studies exploit the fact that different factors affecting climate have different characteristic signatures. These unique attributes are clearer in detailed patterns of climate change than in records like the average temperature of Earth’s surface. Fingerprinting is a powerful tool for separating human and natural climate-change signals. Results from this research provided scientific support for the historic 1995 findings of a “discernible human influence” on global climate. Fingerprinting also contributed to work recognized by the 2021 Nobel Prize in Physics. My presentation will look back at efforts to understand the causes of climate change with fingerprint methods. It will also address some of the key scientific challenges ahead, particularly in terms of communicating climate change science and assessing human contributions to the changing likelihood of extreme events.

Ben Santer is an atmospheric scientist. He retired from Lawrence Livermore National Laboratory in 2021. He is now a Fowler Distinguished Scholar in Residence at Woods Hole Oceanographic Institution and a Visiting Researcher at UCLA’s Joint Institute for Regional Earth System Science & Engineering. He studies natural and human “fingerprints” in observed climate records. His early research contributed to the historic 1995 conclusion of the Intergovernmental Panel on Climate Change: “the balance of evidence suggests a discernible human influence on global climate”. He served as lead author of a key chapter of that report. Since 1995, Ben has identified human fingerprints in atmospheric temperature and water vapor, ocean heat content, sea surface temperature in hurricane formation regions, and many other climate variables. In his spare time, Ben is an avid rock-climber and mountaineer.