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Semiquantitative Estimates of Rainfall Variability During the 8.2 kyr Event in California Using Speleothem Calcium Isotope Ratios
Author(s) -
de Wet Cameron B.,
Erhardt Andrea M.,
Sharp Warren D.,
Marks Naomi E.,
Bradbury Harold J.,
Turchyn Alexandra V.,
Xu Yiruo,
Oster Jessica L.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl089154
Subject(s) - speleothem , stalagmite , cave , geology , magnitude (astronomy) , climatology , δ18o , subtropics , environmental science , stable isotope ratio , holocene , oceanography , geography , ecology , physics , archaeology , quantum mechanics , astronomy , biology
A multiproxy record from a fast‐growing stalagmite reveals variable hydroclimate on the California coast across the 8.2 kyr event and a precursor event likely caused by initial drainage of proglacial Lake Agassiz. Using speleothem δ 44 Ca, we develop the first semiquantitative estimates of paleorainfall variability for California through calibration with measurements of the modern climate and cave environment. We find that the magnitude of rainfall variability during the 8.2 kyr event approached the multiyear variability observable in the recent past (1950–2019) and the magnitude of variability during the precursor event likely exceeded this range. Additionally, we observe other instances of multidecadal variability comparable in magnitude to the precursor event during the record. Our work suggests that speleothem calcium isotope ratios are a powerful semiquantitative means to reconstruct paleorainfall, although numerous factors must be assessed in each cave system before applying this approach.