Geomagnetic reversal dating
That weakening and reversal was supposed to take on the order of several thousand years.A new study by an international team of scientists, however, demonstrates that the last magnetic reversal – 786,000 years ago – actually happened very quickly, in less than 100 years, or roughly the span of a modern human lifetime.Though a magnetic reversal is a major planet-wide event driven by convection in Earth’s iron core, there are no documented catastrophes associated with past reversals, despite much searching in the geologic and biologic record.Today, however, such a reversal could potentially wreak havoc with our electrical grid, generating currents that might take it down.(a) The summer monsoon front (brown belt) and summer monsoon directions (red arrows) are after Porter and An In this study, we examined the East-Asian monsoon response to millennial-scale climate events during the MIS 19 interglacial using high-resolution magnetic susceptibility (χ), the frequency dependence of magnetic susceptibility (χ), and grain size records from Xifeng and Lingtai in the CLP (Fig. High-resolution Matuyama–Brunhes (MB) transition records were previously obtained from the same sections of these areas16 μm) fraction and median grain size of the WM proxies in Xifeng were 14–40% and 7–12 μm, respectively, showing an inverse correlation with SM in the long wavelengths of the strength changes (Fig. These correlations are different from most of the previous studies that correlated paleosol layer S7 with MIS 19, and layer S8 with MIS 21.
Past East-Asian monsoon variations are recorded in loess-paleosol sequences on the Chinese Loess Plateau (CLP), where aeolian dust transported from deserts mainly north–northwest by the WM has been deposited since about 2.6 Ma. Paired arrowheads indicate summer (SM) and winter (WM) monsoon inverse correlations. 2j,k), whereas the average grain size was coarser, due mainly to the lowermost coarse portion below about 600 cm (Fig. The SM and WM in Lingtai also showed inverse correlations in the short episodes between 170 and 320 cm and below 650 cm (Fig. However, there were no inverse correlations in the long-wavelength changes between 340 and 540 cm in Lingtai (Supplementary Fig. In and below the MBpf zone, the WM showed oscillatory intensification with no correlation with the SM, as highlighted in green for the maxima in Fig. The SM proxies of χ and χ showed consistent variation, with both having a sharp SM peak in the S7 layer and double SM peaks in the S8 layer, designated “x1”, “x4”, and “x5”, respectively, and a short SM minimum of L8 at 228 cm in Xifeng and 281 cm in Lingtai (Fig. Changes in χ in the Chinese loess-paleosol sequences are consistent with marine oxygen isotope ratios, which are proxies of land ice volume and glacial sea-level changes.
Our correlation scheme is based on the small lock-in depth supported by laboratory experiments and field observations (see Method for details). These results suggest that the brief high sea-level/warming (low sea-level/cooling) events in the North Atlantic and Northwest Pacific mid-latitudes left traces in the climate in the CLP as SM strengthening (weakening) events.
In contrast, those of highstand MISs 18.3, 18.1, 17.5, and 17.1 were evidently below the sill because the corresponding marine layers are absent in the sequence, despite the lack of a hiatus in deposition O curve is tuned to the ice volume model in (b). Such a climate teleconnection might have occurred through atmospheric circulation (e.g., the Westerlies).
Renne said: What’s incredible is that you go from reverse polarity to a field that is normal with essentially nothing in between, which means it had to have happened very quickly, probably in less than 100 years.
We don’t know whether the next reversal will occur as suddenly as this one did, but we also don’t know that it won’t.