Spatial distribution of Pleistocene/Holocene warming amplitudes in Northern Eurasia inferred from geothermal data
Résumé
We analyze 48 geothermal estimates of Pleistocene/Holocene warming amplitude from various locations in Greenland, Europe, Arctic regions of Western Siberia, and Yakutia. The spatial distribution of these estimates exhibits two remarkable features. (i) In Europe and part of Asia the amplitude of warming increases towards northwest and displays clear asymmetry with respect to the North Pole. The region of maximal warming is close to the North Atlantic. A simple parametric dependence of the amplitude on the distance to the warming center explains 91% of the amplitude variation. The Pleistocene/Holocene warming center is located northeast of Iceland. We claim that the Holocene warming is primarily related to the formation (or resumption) of the modern system of currents in the North Atlantic. (ii) In Arctic Asia, north of the 68-th parallel, the amplitude sharply decreases from South to North, reaching zero and even negative values. Too small amplitudes could be attributed to a joint warming influence of Late Pleistocene ice sheets and warm-water lakes formed in Late Pleistocene by the damming of the Ob, Yenisei and Lena Rivers. Using a simple model of the temperature regime underneath the ice sheet we show that, depending on the relationship between the heat flow and the vertical ice advection velocity, the base of the glacier can either warm up or cool down.
Origine : Accord explicite pour ce dépôt
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