Research Center for Inland Seas, and Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan.
Proc Natl Acad Sci U S A. 2013 Jan 22;110(4):1215-20. doi: 10.1073/pnas.1213389110. Epub 2013 Jan 7.
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 CR 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% of its present value, for which we estimate >40% increase in CR flux. The climate warmed rapidly when field intensity recovered. We suggest that geomagnetic field intensity can influence global climate through the modulation of CR flux.
银河宇宙射线（CRs）诱发云形成的气候效应最近成为讨论的热点。CR 与云的关联表明，地磁场强度的变化可能通过调节 CR 通量来改变气候。然而，这一假设并没有得到稳健的地质证据的充分验证。在这里，我们展示了五个间冰期的古气候和古环境记录，其中包括两次地磁极性反转。海洋氧同位素阶段 19 和 31 分别在海平面高位期间和马修马-布容和下雅拉米洛反转期间包含异常冷却间隔。这与典型的间冰期气候形成鲜明对比，典型的间冰期气候在海平面峰值时温度达到最高。当磁场强度下降到目前强度的<40%时，发生了冷却，我们估计 CR 通量增加了>40%。当磁场强度恢复时，气候迅速变暖。我们认为，地磁场强度可以通过调节 CR 通量来影响全球气候。
