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Ice Cores Determine Timings Of Past Climate Changes

04.01.2016
04.01.2016 15:18 Age: 2 yrs

Two deep ice cores drilled at the East Antarctic dome summits 'Dome Fuji' and 'Dome C' were volcanically synchronized over the past 216 kyr to improve our knowledge of the timing and duration of the Marine Isotope Stage 5 climate period (80-130 kya)

Click to enlarge. Figure 1. This is a picture of the distribution of the volcanic matching points in the Age-Depth plot. Courtesy: Fujita S. et al.

Click to enlarge. Figure 2. Locations of where the ice cores were obtained in Antarctica. Dome Fuji is located in the Atlantic Ocean and Indian Ocean sector, and Dome C is located in the Indian Ocean Sector. Courtesy: Fujita S./NIPR.

 

From the Research Organization of Information and Systems

Ice core records are rich archives of the climate history during glacial-interglacial cycles over timescales of up to ~800 kyr before the current age. In ice core studies, the accurate and precise dating of the core samples is a central issue that must be investigated to better constrain the timing, sequence, and duration of past climatic events.

To help solve this issue, two deep ice cores were drilled at the remote dome summits Dome Fuji (DF) and EPICA Dome C (EDC) in Antarctica (Figure 1) and were subsequently synchronized in time by matching identical volcanic events. Precise synchronization was possible because large volcanic eruptions on the earth can be commonly identified in ice cores due to the presence of high concentrations of sulfuric acid. A total of 1401 volcanic matching points were identified within the past 216 kyr (Figure 2). These matching points were then used to precisely compare the two chronologies between these ice cores. The ages between the matching points in the cores were within 2 kyr, except during the last interglacial period referred to as "Marine Isotope Stage (MIS) 5", which occurred from 80-130 kya. The DF core produced ages that were older than the EDC core, with peak values in the age difference of 4.5 kyr at MIS 5d (ca. 120 kya) and 3.1kyr at MIS 5b (ca. 90 kya).

The causes of the age differences at MIS 5 were proposed to occur from (i) an overestimation of the surface mass balance at around MIS 5d-6 in the glaciological model, and (ii) an error in one of the age constraints by ~3 kyr at MIS 5b. Additionally, we found that changes in the water stable isotope signatures in the ice at DF tended to occur before the same changes at EDC, with the time between changes being more pronounced during cold periods. The results suggested that signals that were indicative of abrupt climate change tended to propagate first at DF and later at EDC. The results of the research have been published in the journal Climate of the Past.

Dr. Shuji Fujita of the National Institute of Polar Research, Tokyo, is one of the two lead authors on the paper and has commented: "Our work contributes establishing a common time scale of ice cores and will be extremely important in studies of temporal and spatial propagation of abrupt climate change in the Antarctic."

Abstract

Two deep ice cores, Dome Fuji (DF) and EPICA Dome C (EDC), drilled at remote dome summits in Antarctica, were volcanically synchronized to improve our understanding of their chronologies. Within the past 216 kyr, 1401 volcanic tie points have been identified. DFO2006 is the chronology for the DF core that strictly follows O2/ N22/ N2 age constraints by ~ 3 kyr at MIS 5b. Overall, we improved our knowledge of the timing and duration of climatic stages at MIS 5. This new understanding will be incorporated into the production of the next common age scale. Additionally, we found that the deuterium signals of ice, δDice, at DF tends to lead the one at EDC, with the DF lead being more pronounced during cold periods. The lead of DF is by +710 years (maximum) at MIS 5d, −230 years (minimum) at MIS 7a and +60 to +126 years on average.

Citation

Volcanic synchronization of Dome Fuji and Dome C Antarctic deep ice cores over the past 216 kyr by S. Fujita, F. Parrenin, M. Severi, H. Motoyama, and E. W. Wolff published in Climate of thePast, DOI doi:10.5194/cp-11-1395-2015.

Read the abstract and get the paper here.

Source

Research Organization of Information and Systems news release issued via EurekAlert! here.