Naslov
Ocean-land interactions determined the specific timing and structure of Termination II

Autori
Domínguez-Villar, David ; Vázquez-Navarro, Juan A. ; Krklec, Kristina ; Lojen, Sonja ; López-Sáez, José A. ; Dorado-Valiño, Miriam ; Farchild, Ian J.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Climate Change: The Karst Record IX (KR9), Programme and Abstracts / Moseley, G. et al. - Innsbruck : University of Innsbruck, 2022, 111-111

Skup
Climate Change: The Karst Record IX (KR9)

Mjesto i datum
Innsbruck, Austrija, 17.07.2022. - 20.07.2022

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Termination II ; glaciation ; tufa, Heinrich event ; climate

Sažetak
Glacial terminations commence when ice-sheets from the Northern Hemisphere reach a supercritical size and their ablation is enhanced due to the increase of insolation during the Northern Hemisphere summer. Terminations reach a no-return point when the thermohaline circulation shuts down abruptly and triggers the bipolar seesaw mechanism that causes non-linear modifications on the global climate. Because of progressive variations of the solar forcing, suitable temporal windows for the occurrence of the bipolar seesaw mechanism exceed 10 ka, which represent a limitation on understanding the precise inception time of the bipolar seesaw mechanism and its causes. Therefore, controls that affect the structure and timing of terminations are still poorly understood. We studied a tufa deposit from the Iberian Peninsula that covers Termination II (T- II) and the previous interglacial period. The studied tufa sequence provides a continuous record due to its specific hydrological and geomorphological setting and enables the possibility to study multiple proxies difficult to study in other karst records. The chronology of the tufa sequence was previously dated by U-Th and geomagnetism techniques and the oxygen isotope signal of the carbonates was synchronized to speleothem records from the Mediterranean to provide the age model of the deposit. We used the same chronology to synchronize ocean sediments from the North Atlantic to correlate major climate events in a common timescale. We identify two stages within T-II. The first stage started with the increase of boreal summer integrated solar insolation, and during this stage three millennial climate oscillations were recorded. These oscillations resulted from complex ocean- atmosphere interactions in the Nordic seas, caused by the progressive decay of Northern Hemisphere ice-sheets. The second stage commenced after a glacial outburst that caused the collapse of the Thermohaline Circulation, a massive Heinrich event (HS11), and the onset of the bipolar seesaw mechanism that eventually permitted the completion of T-II. The pace of the millennial oscillations during the first stage of T-II controlled the onset of the second stage, when the termination became a non-reversible and global phenomenon that accelerated the deglaciation. During the last two terminations, the bipolar seesaw mechanism was triggered by different detailed climate interactions, which suggests the occurrence of different modes of terminations.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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