This event will be held remotely over Zoom; please go here to attend!
Title: Understanding past, present, and future changes to the water cycle: new methods for signal detection and attribution
Abstract: How is climate change affecting the Earth's hydrological cycle? And what can we expect in the future? Currently, the detection of external influences on hydrological variables is complicated by several factors: methodological uncertainties, large internal variability, errors in the computer models used to estimate natural climate variability and future climate trajectories, and fundamentally unresolved science questions. In this talk, I’ll explain how new methods can help to identify clear signals amidst the noise. I’ll begin in the past, using tree-ring reconstructions of last-millennium hydroclimate to show that humans were very likely influencing global drought risk as early as the first half of the twentieth century. Moving to the present, I’ll show how improved fingerprinting techniques reveal a detectable human influence on global and regional precipitation patterns. I’ll end with a cautionary tale for the future, showing that estimates of future warming or “equilibrium climate sensitivity” inferred from recent observations are likely biased low, because the cloud changes we've experienced are not necessarily predictive or reflective of the cloud changes expected in the future. This means that conclusions inferred from past and present data cannot be simply extended to the future, but this improved understanding can help to narrow uncertainties in future climate projections.