Geomagnetic paleointensity variation with a 100 kyr quasi-period

We analyzed records of geomagnetic field intensity (paleointensity) during the last 700 kyr in five sediment cores from a wide region of the Pacific Ocean. A global paleointensity variation with a 100 kyr quasi-period was successfully extracted using the wavelet transform. Because the variation does not correlate with that of magnetic properties of the sediments, it originated from a change in the geomagnetic field. The 100 kyr quasi-period of the geomagnetic field is close to the timescales of eccentricity, one of the Earth’s orbital elements, and of the glacial–interglacial cycle of the late Quaternary paleoclimate. In particular, there is a correlation between the variations of the geomagnetic field intensity and climate with an 18 kyr time lag. While the geodynamo has widely been thought to be a self-sustained system, our results support the possibility of an external energy supply of the variation through orbital forcing or climate change.