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The 4.2 ka event, ENSO, and coral reef development
Ist Teil von
Climate of the past, 2019-01, Vol.15 (1), p.105-119
Ort / Verlag
Katlenburg-Lindau: Copernicus GmbH
Erscheinungsjahr
2019
Link zum Volltext
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
Variability of sea-surface temperature related to shifts in the mode of the El
Niño–Southern Oscillation (ENSO) has been implicated as a possible forcing mechanism
for the global-scale changes in tropical and subtropical precipitation known as the 4.2 ka event. We
review records of coral reef development and paleoceanography from the tropical eastern
Pacific (TEP) to evaluate the potential impact of the 4.2 ka event on coral reefs. Our
goal is to identify the regional climatic and oceanographic drivers of a 2500-year
shutdown of vertical reef accretion in the TEP after 4.2 ka. The 2500-year hiatus
represents ∼40 % of the Holocene history of reefs in the TEP and appears to
have been tied to increased variability of ENSO. When ENSO variability abated
approximately 1.7–1.6 ka, coral populations recovered and vertical accretion of reef
framework resumed apace. There is some evidence that the 4.2 ka event suppressed coral
growth and reef accretion elsewhere in the Pacific Ocean as well. Although the ultimate
causality behind the global 4.2 ka event remains elusive, correlations between shifts in
ENSO variability and the impacts of the 4.2 ka event suggest that ENSO could have played
a role in climatic changes at that time, at least in the tropical and subtropical
Pacific. We outline a framework for testing hypotheses of where and under what conditions
ENSO may be expected to have impacted coral reef environments around 4.2 ka. Although
most studies of the 4.2 ka event have focused on terrestrial environments, we suggest
that understanding the event in marine systems may prove to be the key to deciphering its
ultimate cause.