Global change: the high-amplitude changes 13-10 ka ago—novel aspects

Abstract

Within the period 13-10 ka, the Earth experienced high-amplitude fluctuations in climate and to a lesser degree, also in sea level. These high-amplitude changes occurred within the period of superposition of two exponential curves in the eustatic rise in sea level. This intermediate period seems to represent the Earth's geodynamic response to the general deceleration due to the sea level rise. The deceleration caused water-masses to move polewards. At a critical point, the symmetry axes of the Earth's core and mantle were displaced with respect to each other along a meridional path recorded in a trans-polar shift of the axis of the geomagnetic dipole field. At about the same time, the Earth came into a new mode with large-scale interchanges of angular momentum between the “solid” Earth and the hydrosphere. These speeding-ups and slowing-downs of the hydrosphere caused increases and decreases in the ocean current system. The Gulf Stream affecting climate and sea level in Europe, the Labrador Current controlling climate and ice marginal changes in the Hudson Strait region. The Humboldt Current controlling climate and precipitation in South America, the coastal upwelling and the marine productivity and in that way also affecting the atmospheric CO 2 content. These ocean current changes are the main controlling factors of the high-amplitude changes within the intermediate period from about 13.5 to 9.5 ka.