Fifty-year investigation of the causal relation between geomagnetic reversal and mass extinction

Geomagnetic field originates from the geodynamo inside Earth's core. It passes through the mantle, crust, biosphere, neutral atmosphere, ionosphere, and then extends into the interplanetary space, and forms a magnetosphere due to interaction with the solar wind. Geomagnetic field can protect the biosphere through two ways: preventing extraterrestrial high energy particles from penetrating inside and confining volatile materials, such as water and atmospheric oxygen, with magnetospheric processes. Geomagnetic field has been thought to play a very important role for retaining the habitability over the Earth's history; however, a reduction of geomagnetic field could impose some catastrophic consequences on the biosphere, even causes mass extinction. Here we review the investigation of the causal relation between geomagnetic reversal and mass extinction over the past 50 years, and comment on the significance of those earlier works focusing on the one-to-one relation by standing on a historical ground. We also introduce the advances of the newly proposed many-to-one relation. It has been suggested that Earth's interior and space environment should be regarded as one system, and some geological events should be understood through a perspective of Earth system science and comparative planetology.