GNGTS 2019 - Atti del 38° Convegno Nazionale

232 GNGTS 2019 S essione 1.4 the Southern Pole has moved at an almost constant rate, following the Antarctic shoreline, with a relevant northward component. This means that it is slowly moving outside of the ice cap. Conversely the Northern Pole has been wandering at a very slow rate between Canada and Greenland for about 400 years to suddenly accelerate in the last 30 years. Until 1990, similarly to the Southern Magnetic Pole, it was located near to land masses and very far away from the Geographic Pole, that is far from the center of mass of the ice cap. Suddenly, it started moving towards the center of the Arctic Sea, away from the land masses and towards the center of mass of the ice cap. It is also noteworthy that the links of the Arctic Sea with the Atlantic and Pacific Oceans are all characterized by relatively shallow depths, not favoring water exchange with the outer areas. The Magnetic Pole location is crucial with respect to two phenomena that could be both involved in the excessive warming. The first effect are the Birkeland Currents, and the induced flows that they cause in the upper atmosphere; the second one are the possibly induced currents in the Arctic Sea caused by the continuous intensity variations of the magnetic field. Birkeland Currents are by far the most interesting candidates. They are caused by the electrically charged particles from Solar Wind. These particles are captured in a sort of spinning vortex centered around the Magnetic Poles. They are extremely powerful, accounting for several TWs, that is almost the same order of magnitude of total human energy consumption. We are obviously thinking to atmospheric heating by Joule effect. It is clear that the upper atmosphere (above 50 km) has an extremely low density and this points toward a not particularly efficient mechanism, however light positive ions such as those that make up the Solar Wind move more efficiently in clean air, that is, above seas and this could sensibly lower the height of current circulation linked to the Birkeland Currents. Unfortunately reliable data do not exist. The other phenomenon could be the existence of induced currents within the Arctic Sea. Its shape closely resembles that of a pot of continental dimensions. Since salted water is an excellent conductor it could simply work on the same principle of an induction oven, where the Northern Magnetic field would be currently positioned in an optimal location to maximize its effects. We understand that the lack of data supporting this view is a serious drawback. However, since the magnetic pole is migrating at a very fast rate towards the russian shoreline, in the next period of about ten years, if such an hypothesis is correct, we should observe an increase of the ice cap surface. References NASA: Ice Sheets | Vital Signs - Climate Change: Vital Signs of the Planet. <https://climate.nasa.gov/vital-signs/ ice-sheets/>. NOAA: Wandering of the Geomagnetic Poles | NCEI. <https://www.ngdc.noaa.gov/geomag/GeomagneticPoles. shtml>. NSIDC: NSIDC Data on Google Earth | National Snow and Ice Data Center. <https://nsidc.org/data/google_earth >. Zharkova V. V., Shepherd S. J., Zharkov S. I. And Popova E.; 2019: Oscillations of the baseline of solar magnetic field and solar irradiance on a millennial timescale. Scientific Reports, doi:10.1038/s41598-019-45584-3.