Ikuko Kitabaa,1, Masayuki Hyodoa, Shigehiro Katohb, David L. Dettmanc, and Hiroshi Satod. Midlatitude cooling caused by geomagnetic field minimum during polarity reversal. doi: 10.1073/pnas.1213389110
PNAS January 22, 2013 vol. 110 no. 4 1215-1220
The climatic effects of cloud formation induced by galactic cosmic rays (CRs) has recently become a topic of much discussion. The CR–cloud connection suggests that variations in geomagnetic field intensity could change climate through modulation of Cosmic Ray flux. This hypothesis, however, is not well-tested using robust geological evidence. Here we present paleoclimate and paleoenvironment records of five interglacial periods that include two geomagnetic polarity reversals. Marine oxygen isotope stages 19 and 31 contain both anomalous cooling intervals during the sea-level highstands and the Matuyama–Brunhes and Lower Jaramillo reversals, respectively. This contrasts strongly with the typical interglacial climate that has the temperature maximum at the sea-level peak. The cooling occurred when the field intensity dropped to 40% increase in Cosmic Ray flux. The climate warmed rapidly when field intensity recovered. We suggest that geomagnetic field intensity can influence global climate through the modulation of Cosmic Ray flux.
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