Cold spells over Greenland during the mid-Pliocene Warm Period

The mid-Pliocene Warm Period (mPWP; 3.26-3.02 Ma) is an interval often suggested as a potential analogue of the near future climate and fate of the Greenland Ice Sheet (GIS). Here, neodymium and lead isotopes from marine sediment cores collected off the southern Greenland margin suggest pulses of intense glacial erosion of Precambrian terranes during this interval, while grain size data indicate a reduction in the strength of contour currents, both following a near obliquity cycle (similar to 41 ka) pacing. These cold spells were thus sufficiently intense to trigger recurrent ice growth over Greenland, even under the high atmospheric CO2 concentration (similar to 400 ppmV) of the interval, before the intensification of the Northern Hemisphere Glaciation (similar to 2.7 Ma). However, the mPWP was marked by a low amplitude in the axial tilt oscillation of the Earth, thus lesser variations in summer insolation at high latitudes than in the present era. Therefore, although it may offer some similarities with the future of the Earth's climate, the mid-Pliocene cannot be seen as a genuine analogue for predicting the fate of the GIS.