(i.e., δ18Osw), have been attributed to increased volcanic activity at the onset of Bølling–Allerød, are associated with the interval of intense volcanic activity, hinting at an interaction between climate and volcanism – enhanced short-term melting of glaciers, possibly via albedo changes from particle fallout on glacier surfaces. The second Weichselian Icelandic ice sheet collapse, onshore (est. net wastage 221 Gt a−1 over 750 years), similar to today's Greenland rates of mass loss, has been attributed to atmospheric Bølling–Allerød warming. Furthermore, the study authors noted: Flora Ice uncovered large parts of north Europe and temperate forests covered Europe from N 29° to 41° latitude. Pioneer vegetation, such as Salix polaris and Dryas octopetala, began to grow in regions that were previously too cold to support these plants. Later, mixed evergreen and deciduous forests prevailed in Eurasia, more deciduous toward the south, just as today. Birch, aspen, spruce, pine, larch and juniper were to be found extensively, mixed with Quercus and Corylus. Poaceae was to be found in more open regions. Fauna During this time late Pleistocene animals spread northward from refugia in the three peninsulas, Iberian Peninsula, Italy and the Balkans. Geneticists can identify the general location by studying degrees of consanguinity in the modern animals of Europe. Many animal species were able to move into regions far more northerly than they could have survived in during the preceding colder periods. Reindeer, horse, saiga, antelope, bison, woolly mammoth and woolly rhinoceros were attested, and were hunted by early man. In the alpine regions ibex and chamois were hunted. Throughout the forest were red deer. Smaller animals, such as fox, wolf, hare and squirrel also appear. Salmon was fished. When this interstadial period ended, with the onset of the Younger Dryas, many of these species were forced to migrate south or become regionally extinct. Causes In recent years research tied the Bølling–Allerød warming to the release of heat from warm waters originating from the deep North Atlantic Ocean, possibly triggered by a strengthening of the Atlantic meridional overturning circulation (AMOC) at the time. Study results which would help to explain the abruptness of the Bølling–Allerød warming, based on observations and simulations, found that 3°–5 °C Ocean warming occurred at intermediate depths in the North Atlantic over several millennia during Heinrich stadial 1 (HS1). The authors postulated that this warm salty water (WSW) layer, situated beneath the colder surface freshwater in the North