Time To Re-examine Use Of Tree Ring Growth Estimates In Climate Models

Rings on a tree. (Credit: Public Domain)

Tree ring growth is a standard means of estimating past climate conditions for many researchers. However, interpretation of tree ring growth is based on different assumptions depending on which climate reconstruction approach is used.

In a release from the University of Otago, researchers compared results using different tree ring climate prediction models to actual climate data and found that incorporating more uncertainty into the ring growth analysis interpretation would likely improve modeling results.

Researchers employed a unified statistical modeling approach utilizing a Bayesian inference that accounts for both climatic and non-climatic variability. The modeling approach was tested against climate data from 121 Scots Pine trees in Northern Sweden from 1496 to 1912.

While other tree-ring-growth-based climate modeling approaches agreed with the unified statistical approach in terms of whether the climate was warming or cooling, the actual temperatures predicted by other similar models varied depending on the underlying assumptions. For example, some models assume it’s possible to perfectly extract climatic influences on tree ring growth from non-climatic influences. Others contain assumptions for convenience, also influencing results and making them diverge.

Top image: Rings on a tree. (Credit: Public Domain)