Publication Date:
2021-03-29
Description:
The Toba eruption that occurred some 74 ka ago in
Sumatra, Indonesia, is among the largest volcanic events on
Earth over the last 2 million years. Tephra from this eruption
has been spread over vast areas in Asia, where it constitutes
a major time marker close to the Marine Isotope Stage 4/5
boundary. As yet, no tephra associated with Toba has been
identified in Greenland or Antarctic ice cores. Based on new
accurate dating of Toba tephra and on accurately dated European
stalagmites, the Toba event is known to occur between
the onsets of Greenland interstadials (GI) 19 and 20. Furthermore,
the existing linking of Greenland and Antarctic ice
cores by gas records and by the bipolar seesaw hypothesis
suggests that the Antarctic counterpart is situated between
Antarctic Isotope Maxima (AIM) 19 and 20.
In this work we suggest a direct synchronization of Greenland
(NGRIP) and Antarctic (EDML) ice cores at the Toba
eruption based on matching of a pattern of bipolar volcanic
spikes. Annual layer counting between volcanic spikes
in both cores allows for a unique match. We first demonstrate
this bipolar matching technique at the already synchronized
Laschamp geomagnetic excursion (41 ka BP) before
we apply it to the suggested Toba interval. The Toba synchronization
pattern covers some 2000 yr in GI-20 and AIM-
19/20 and includes nine acidity peaks that are recognized in
both ice cores.
The suggested bipolar Toba synchronization has decadal
precision. It thus allows a determination of the exact phasing
of inter-hemispheric climate in a time interval of poorly
constrained ice core records, and it allows for a discussion
of the climatic impact of the Toba eruption in a global perspective.
The bipolar linking gives no support for a long-term
global cooling caused by the Toba eruption as Antarctica experiences
a major warming shortly after the event. Furthermore,
our bipolar match provides a way to place palaeoenvironmental
records other than ice cores into a precise climatic
context.
Keywords:
Greenland; Antarctic ice cores; Toba eruption
;
551
Language:
English
Type:
article
,
publishedVersion
Format:
18
Permalink
