The divergence phenomenon in tree-ring-reconstructed temperatures: global problem or Northern Hemisphere anomaly?

Estimates of current global warming are based on comparing directly observed temperatures with past temperatures reconstructed from climate proxies such as tree rings and corals. Recent studies have shown that tree-rings from some high-latitude Northern Hemisphere sites are becoming less sensitive to temperature variability, raising concerns about the quality of historical temperature reconstructions. Our project will undertake the first examination of Southern Hemisphere tree-ring chronologies for this divergence phenomenon. We will update existing chronologies in Tasmania, New Zealand and South America and apply novel tools for high-resolution tree growth and climate monitoring to determine the scale, extent, and drivers of divergence.