| 1. |
- Jiang, Hui, et al.
(författare)
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Solar forcing of Holocene summer sea-surface temperatures in the northern North Atlantic
- 2015
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Ingår i: Geology. - 0091-7613. ; 43:3, s. 203-206
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Tidskriftsartikel (refereegranskat)abstract
- Mounting evidence from proxy records suggests that variations in solar activity have played a significant role in triggering past climate changes. However, the mechanisms for sun-climate links remain a topic of debate. Here we present a high-resolution summer sea-surface temperature (SST) record covering the past 9300 yr from a site located at the present-day boundary between polar and Atlantic surface-water masses. The record is age constrained via the identification of 15 independently dated tephra markers from terrestrial archives, circumventing marine reservoir age variability problems. Our results indicate a close link between solar activity and SSTs in the northern North Atlantic during the past 4000 yr; they suggest that the climate system in this area is more susceptible to the influence of solar variations during cool periods with less vigorous ocean circulation. Furthermore, the high-resolution SST record indicates that climate in the North Atlantic regions follows solar activity variations on multidecadal to centennial time scales.
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| 2. |
- Li, Dongling, et al.
(författare)
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East Asian Winter Monsoon Variations and Their Links to Arctic Sea Ice During the Last Millennium, Inferred From Sea Surface Temperatures in the Okinawa Trough
- 2018
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Ingår i: Paleoceanography and Paleoclimatology. - 2572-4517. ; 33:1, s. 61-75
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Tidskriftsartikel (refereegranskat)abstract
- The East Asian winter monsoon (EAWM) significantly impacts living conditions in a large part of Asia, and therefore, it is important to understand its major driving mechanisms. Winter sea surface temperature (SSTW) and circulation in the southern Okinawa Trough are today both primarily controlled by the EAWM. Here we present a new SSTW reconstruction for the last millennium based on a diatom record from sediment core MD05-2908, from the continental slope of the southern Okinawa Trough off northeastern Taiwan. Our reconstruction indicates that SSTW varied between 14.1 and 19.6°C over the past 1,000 years. Changes in SSTW in the southern Okinawa Trough correspond closely to the index of warm winters based on historical documents from the East Asian monsoon domain. This implies that our SSTW record can be used to reconstruct EAWM variability during the last millennium. Comparisons with the reconstructed winter Arctic Oscillation (AO, developed from historical snow anomaly events in Eastern Asia) and Arctic sea ice cover reveal a significant positive correlation between the EAWM and AO during the time interval from 1000–1400 Common Era (C.E.), coinciding with reduced sea ice cover. However, there is no significant correlation with increased sea ice cover during the interval from 1400 to 1700 C.E. This suggests that the reduction in Arctic sea ice may periodically have played a role in strengthening the relationship between the EAWM and the AO during the last millennium and that the current and future reduction in Arctic sea ice may have significant consequences for the EAWM.
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| 3. |
- Sha, Longbin, et al.
(författare)
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Diatom-reconstructed summer sea-surface temperatures and climatic events off North Iceland during the last deglaciation and Holocene
- 2022
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182. ; 602
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Tidskriftsartikel (refereegranskat)abstract
- Lateglacial and Holocene summer sea-surface temperature (SST) variability in the northern North Atlantic was reconstructed based on diatom records from two sediment cores from the North Icelandic shelf. The temperature changes are discussed in relation to palaeoceanographic circulation patterns and past climatic changes. Modern diatom data from surface sediments from around Iceland and Southeast and West Greenland, with known modern environmental variables, were used as the basis for the quantitative reconstruction of summer SST. The results show that summer SSTs varied during both the Lateglacial and the Holocene, but the amplitude of SST variations during the Lateglacial was greater than that during the Holocene. No pronounced warm or cool events were recorded on the North Icelandic shelf during the GI-1e to GI-1a events (Bølling-Allerød) and the GS-1 event (Younger Dryas). The changes in SST were possibly caused by major changes in the ocean circulation pattern around Iceland, and by minor variations in the interaction between the cold and warm currents in the region. Comparison of the reconstructed summer SSTs with other marine records from the North Atlantic suggests an antiphase relationship between the oceanic climatic responses off North Iceland and in the eastern North Atlantic during the Lateglacial and the earliest part of the Holocene (the Preboreal).
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| 4. |
- Sha, Longbin, et al.
(författare)
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Solar forcing as an important trigger for West Greenland sea-ice variability over the last millennium
- 2016
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 131, s. 148-156
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Tidskriftsartikel (refereegranskat)abstract
- Arctic sea ice represents an important component of the climate system, and the present reduction of sea ice in the Arctic is of major concern. Despite its importance, little is known about past changes in sea-ice cover and the underlying forcing mechanisms. Here, we use diatom assemblages from a marine sediment core collected from the West Greenland shelf to reconstruct changes in sea-ice cover over the last millennium. The proxy-based reconstruction demonstrates a generally strong link between changes in sea-ice cover and solar variability during the last millennium. Weaker (or stronger) solar forcing may result in the increase (or decrease) in sea-ice cover west of Greenland. In addition, model simulations show that variations in solar activity not only affect local sea-ice formation, but also control the sea-ice transport from the Arctic Ocean through a sea-ice-ocean-atmosphere feedback mechanism. The role of solar forcing, however, appears to have been more ambiguous during an interval around AD 1500, after the transition from the Medieval Climate Anomaly to the Little Ice Age, likely to be driven by a range of factors. (C) 2015 Elsevier Ltd. All rights reserved.
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