![]() This oceanic teleconnection, called the bipolar seesaw, also affects atmospheric circulation by regulating the temperature gradient between the middle and high latitudes 12, which shifts the intertropical convergence zone north when AMOC rate is high (Northern Hemisphere/Southern Hemisphere warm/cold periods) and south when AMOC rate is decreased (Northern Hemisphere/ Southern Hemisphere cold/warm periods) 13. Changes to the intensity of AMOC result in out-of-phase polar temperature cycles 11 recorded by isotopic climate proxies in ice cores, identified as Dansgaard-Oeschger cycles in the Greenland ice core records and Antarctic Isotope Maxima (AIM) events in Antarctic ice core records. Millennial-scale Southern Ocean temperature oscillations are driven by a feedback between ocean-atmosphere teleconnections that is modulated by Atlantic Meridional Overturn Circulation (AMOC): 10 the mean state ocean circulation responsible for cross-equatorial heat transport from the Southern Hemisphere to the Northern Hemisphere. On millennial timescales this feedback could cause substantial velocity changes in these fast-flowing ice drainage pathways 8, ultimately affecting continent-wide ice sheet mass balance 9. Ice sheet models suggest that ice shelf decay can result in enhanced flow of grounded ice up to 1000 km upstream of the grounding lines of large outlet glaciers and ice streams 7. Ice sheet stability is regulated by ice shelves 5 and grounding line positions 6, which are vulnerable to thinning and retreat when contacted by warm ocean waters. The key link between this ocean-thermal forcing and ice sheet mass lies in the delivery of heat to the ice sheet margins, which affect ice shelves and grounding lines. ![]() Modern observations 2, 3 of retreating ice near marine-terminating ice sheet margins demonstrate the potential for rapid AIS mass fluctuations brought on by changing Southern Ocean temperature 4 (hereafter referred to as ocean-thermal forcing). One of the persistent challenges involved in both reconstructions and projections of global mean sea level is determining what sectors of the Antarctic Ice Sheet (AIS) are vulnerable to significant retreat, the timescales of such retreat, and the conditions that trigger ice loss events 1. Our findings imply that oscillating Southern Ocean temperatures drive a dynamic response in the Antarctic ice sheet on millennial timescales, regardless of the background climate state. These freeze-flush cycles represent cyclic changes in subglacial hydrologic-connectivity driven by ice sheet velocity fluctuations. Geochemical and geochronologic data provide evidence for opal formation during cold periods via cryoconcentration of subglacial brine, and calcite formation during warm periods through the addition of subglacial meltwater originating from the ice sheet interior. Here we present a >100kyr archive of periodic transitions in subglacial precipitate mineralogy that are synchronous with Late Pleistocene millennial-scale climate cycles. However, the distal location and short temporal coverage of these records leads to uncertainty in both the spatial footprint of ice loss, and whether millennial-scale ice response occurs outside of glacial terminations. Once the precipitate has been recovered, the resulting powder may be called a "flower.Ice cores and offshore sedimentary records demonstrate enhanced ice loss along Antarctic coastal margins during millennial-scale warm intervals within the last glacial termination. A common sedimentation technique is centrifugation. Sedimentation refers to any procedure that separates the precipitate from the liquid portion of the solution, which is called the supernate. If the particle size of the insoluble compound is very small or there is insufficient gravity to draw the solid to the bottom of the container, the precipitate may be evenly distributed throughout the liquid, forming a suspension. The solid that is formed is called the precipitate. A chemical that causes a solid to form in a liquid solution is called a precipitant. Here's how it works: forming a solid from a solution is called precipitation. The terminology can seem a bit confusing. ![]() They are used for purification, removing or recovering salts, for making pigments, and to identify substances in qualitative analysis. ![]() Precipitation reactions serve important functions.The solid that forms via a precipitation reaction is called the precipitate.To precipitate is to form an insoluble compound, either by decreasing the solubility of a compound or by reacting two salt solutions.In chemistry, precipitate is both a verb and a noun. ![]()
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