Overview
- A July 2025 Nature Geoscience study by Peking University and USC researchers confirms the inner core stopped and began rotating opposite to Earth’s surface after slowing since 2009.
- Analysis of seismic waves from 1990 to 2021 revealed subtle changes in wave speed and trajectory that pinpoint the reversal of the solid iron-nickel core.
- The reversal marks the start of a roughly 60–70-year oscillation cycle first hypothesized after a 1970s directional shift.
- Scientists are evaluating how the new rotation phase may alter the geodynamo and modify the strength and structure of Earth’s magnetic field.
- Researchers warn that millisecond-scale variations in day length driven by core oscillations could have cumulative effects on long-term climate patterns.