The Maunder Minimum; an interlaboratory comparison of Delta (super 14) C from AD 1688 to AD 1710.

Abstract

Measurements on same-age tree-ring samples from proximal Ural Mountain trees by the Ioffe Institute research group and at the University of Arizona demonstrate a variance corresponding to a standard deviation of + or -5.1 per mil for Ioffe compared to + or -2.1 per mil for Tucson. There is also a calibration difference of 4.3+ or -1.2 sigma per mil. Comparison of the same years measured in Seattle on wood from the Pacific Northwest shows an offset of 2.2+ or -0.5 sigma per mil. This is not a calibration error, but rather is expected from the well-documented evidence for divergence and upwelling of (super 14) C-depleted CO (sub 2) along the west coast of North America.