Model results for "A Global Environmental Crisis 42,000 Years Ago"

Abstract

Geological archives record multiple reversals of Earth’s magnetic poles but the global impacts of these events, if any, remain unclear. Uncertain radiocarbon calibration has limited investigation of the potential effects of the last major magnetic inversion, known as the Laschamps Excursion (41–42ka). Here we use ancient New Zealand kauri trees (Agathis australis) to develop a detailed record of atmospheric radiocarbon levels across the Laschamps. We precisely characterize the geomagnetic reversal and perform global chemistry-climate modelling and detailed radiocarbon-dating of paleoenvironmental records to investigate impacts. We find that geomagnetic field minima ~42ka in combination with Grand Solar Minima caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.