A 2021 study appearing in Nature Communications by Buentgen et al reports on the results of a double-blind experiment of 15 different groups that yielded 15 different Northern Hemisphere summer temperature reconstructions. Each group used the same network of regional tree-ring width datasets.
Hat-tip: Klimaschau 108
What’s fascinating is that ll groups, though using the same data network, came up with a different result. When it comes to deriving temperatures from tree-rings, it has much to do with individual approach and interpretation. Sure we can follow the science, but whose results?
The 15 groups (referred to as R1–R15) were challenged with the same task of developing the most reliable NH summer temperature reconstruction for the Common Era from nine high-elevation/high-latitude TRW datasets (Fig. 1):
Cropped from Figure 1, Buentgen et al
The 15 groups who contributed independently to this experiment all had experience in developing tree ring-based climate reconstructions. But as the study describes, each group employed a distinct reconstruction approach. In summary, the results ranged by as much as 1°C.
How could the groups come up with different results?
The paper’s abstract summarizes: “Differing in their mean, variance, amplitude, sensitivity, and persistence, the ensemble members demonstrate the influence of subjectivity in the reconstruction process. We therefore recommend the routine use of ensemble reconstruction approaches to provide a more consensual picture of past climate variability.”