Dr. Amy Hessl

No Analogue: What Can Tree Rings Tell Us in a Changed Climate?

In the early 1900s, an astronomer named A. E. Douglass attempted to use the annual rings of trees to reconstruct sunspot cycles. Through careful observation, he developed a method we call crossdating to date tree rings from living and dead wood to the calendar year. While Douglass failed to create a reliable history of sunspots, he recognized the potential for tree rings to build long histories of past environments, date archeological sites and, with Willard Libby, calibrate the radiocarbon scale. Over the 20th century, the field of dendrochronology contributed to major discoveries in a range of disciplines from archeology to climatology. By the turn of the 21st century, climate change became the overwhelming focus of paleoenvironmental studies and tree rings played a central role in confirming the reality of our changed climate. Ironically, with this discovery, dendrochronology also confirmed that the recent past is no longer an analogue for the future climate. With the climate debate settled, and the past seemingly not as relevant to understanding future climate, studies of past environments via tree rings and other environmental archives seemed destined for the dustbin of history. In this talk, I challenge this view and argue that long tree ring records are a rare and precious paleoenvironmental archive that continue to yield new discoveries about the history of our planet, society, and the sun. Environmental archives continue to astound and need young passionate scientists to discover, safeguard, and mine them for the yet unknown histories they contain.