Resolving troubling discord in Boreal versus Austral late Holocene temperature history

According to temperature reconstructions based on natural climate proxy archives (ice cores, lake sediments, tree rings etc.), Northern and Southern Hemisphere (NH, SH) temperature histories differ in important features over the past millennia.

This stands in contrast to the broad hemispheric agreement found in corresponding climate model simulations.I hypothesize that a new tree-ring proxy, based on quantitative wood anatomy, can be used to improve temperature reconstructions in both hemispheres, and by this reduce differences between reconstructions and simulations.

Preliminary studies show such results at regional scales in Eurasia, and Hemispheric scale networks based on quantitative wood anatomy are thus expected to confirm my hypothesis.

These advances will be novel and highly relevant to communities engaged in climate modelling, climate reconstructions, and human history research.To test my hypothesis, the project is divided into the following aims:1.Create Boreal and Austral networks of quantitative wood anatomy data from tree rings from already sampled, as well as newly sampled trees growing in extra-tropical regions.2.Use the new proxy data to examine volcanic-related responses specifically in the SH, where model simulations and existing proxy reconstructions clearly disagree.3.Investigate if intra- and inter-hemispheric patterns of long-term temperature changes are more coherent among the new proxy records, and less different from corresponding model simulations.I am convinced that the results of this project will substantially improve upon the quality of both NH and SH temperature reconstructions, but if improved NH and SH reconstructions remain distinct from corresponding simulations, this may constitute an important basis for revisiting system physics implemented in current climate models.

The outcome of these investigations will thus likely challenge conventional wisdom in at least one, and possibly several research communities.