had severe worldwide climate consequences. Effects Abrupt climate change has likely been the cause of wide-ranging and severe effects: Mass extinctions in the past, most notably the Permian–Triassic extinction event (often referred colloquially to as the Great Dying) and the Carboniferous Rainforest Collapse, have been suggested as a consequence of abrupt climate change. Loss of biodiversity: without interference from abrupt climate change and other extinction events, the biodiversity of Earth would continue to grow. Changes in ocean circulation such as: Increasing frequency of El Niño events Potential disruption to the thermohaline circulation, such as that which may have occurred during the Younger Dryas event. Changes to the North Atlantic oscillation Changes in Atlantic Meridional Overturning Circulation (AMOC) which could contribute to more severe weather events. Climate feedback effects One source of abrupt climate change effects is a feedback process, in which a warming event causes a change that adds to further warming. The same can apply to cooling. Examples of such feedback processes are: Ice–albedo feedback in which the advance or retreat of ice cover alters the albedo ("whiteness") of the earth and its ability to absorb the sun's energy. Soil carbon feedback is the release of carbon from soils in response to global warming. The dying and the burning of forests by global warming. Volcanism Isostatic rebound in response to glacier retreat (unloading) and increased local salinity have been attributed to increased volcanic activity at the onset of the abrupt Bølling-Allerød warming. They 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. Past events Several periods of abrupt climate change have been identified in the paleoclimatic record. Notable examples include: About 25 climate shifts, called Dansgaard-Oeschger cycles, which have been identified in the ice core record during the glacial period over the past 100,000 years. The Younger Dryas event, notably its sudden end. It is the most recent of the Dansgaard-Oeschger cycles and began 12,900 years ago and moved back into a warm-and-wet climate regime about 11,600 years ago. It has been suggested that "the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the North Atlantic climate system."