We use paleoclimate proxies, biological and geological archives that record past climatic conditions, to study natural climate variability and to put current and future climatic changes in a long-term context. Climate history of the past ~1,000 years is of particular interest, because it allows us to look at policy-relevant (decadal to centennial) time-scales and to link climate history to the best-documented period of human history. Tree rings are the most widely used climate proxy to study recent climate history and a century of dendrochronological research has resulted in a broad network of tree-ring chronologies that allows us to study the drivers of continental- to hemispheric-scale climate dynamical patterns over multiple centuries. Here, I will present two studies in which we used tree-ring data to reconstruct long-term variability in: 1) the position of the North Atlantic Jet stream, and 2) the Northern Hemisphere Hadley Circulation Extent. I will discuss what our reconstructions tell us about past variability in these climate patterns, how they are linked to ecosystem and human history, and why this information is important for future climate research.
