Overview
- This week’s geodetic study led by Christos Kotsakis shows polar uplift has roughly doubled since the late 1990s from about 0.5 mm per year to roughly 1.0 mm per year, making the solid Earth measurably less flattened.
- A NASA Jet Propulsion Laboratory analysis led by Donald Argus finds seasonal movement of roughly 6,300 billion tonnes of water moves the planet’s center of mass by several millimetres and reduces earlier estimates of annual fluctuation by about half.
- Melting ice drives mass from high latitudes into the oceans, which makes the solid surface rounder while concentrating mass toward the equator and flattening the gravity field in opposite fashion.
- A Nature study by Huifeng Zhang and Mathieu Dumberry proposes the solid inner core oscillates on a roughly 70‑year cycle and deforms viscously with surface shifts on the order of ten metres, but seismologists offer competing explanations for core motion.
- Together, high‑precision GPS, gravity satellites and long‑term seismology are converging on a clearer picture with practical consequences for centimetre‑to‑millimetre geodesy, satellite navigation and international timekeeping that will require further cross‑validation.