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Equatorial Pacific coral geochemical records show recent weakening of the Walker Circulation

Carilli, Jessica E.; McGregor, Helen V.; Gaudry, Jessica J.; Donner, Simon D.; Gagan, Michael K.; Stevenson, Samantha; Wong, Henri; Fink, David

Description

Equatorial Pacific ocean-atmosphere interactions affect climate globally, and a key component of the coupled system is the Walker Circulation, which is driven by sea surface temperature (SST) gradients across the equatorial Pacific. There is conflicting evidence as to whether the SST gradient and Walker Circulation have strengthened or weakened over the late twentieth century. We present new records of SST and sea surface salinity (SSS) spanning 1959–2010 based on paired measurements of Sr/Ca...[Show more]

dc.contributor.authorCarilli, Jessica E.
dc.contributor.authorMcGregor, Helen V.
dc.contributor.authorGaudry, Jessica J.
dc.contributor.authorDonner, Simon D.
dc.contributor.authorGagan, Michael K.
dc.contributor.authorStevenson, Samantha
dc.contributor.authorWong, Henri
dc.contributor.authorFink, David
dc.date.accessioned2015-03-25T01:54:26Z
dc.identifier.issn0883-8305
dc.identifier.urihttp://hdl.handle.net/1885/13043
dc.description.abstractEquatorial Pacific ocean-atmosphere interactions affect climate globally, and a key component of the coupled system is the Walker Circulation, which is driven by sea surface temperature (SST) gradients across the equatorial Pacific. There is conflicting evidence as to whether the SST gradient and Walker Circulation have strengthened or weakened over the late twentieth century. We present new records of SST and sea surface salinity (SSS) spanning 1959–2010 based on paired measurements of Sr/Ca and δ18O in a massive Porites coral from Butaritari atoll in the Gilbert Islands, Republic of Kiribati, in the central western equatorial Pacific. The records show 2–7 year variability correlated with the El Niño–Southern Oscillation (ENSO) and corresponding shifts in the extent of the Indo-Pacific Warm Pool, and decadal-scale signals related to the Pacific Decadal Oscillation and the Pacific Warm Pool Index. In addition, the Butaritari coral records reveal a small but significant increase in SST (0.39°C) from 1959 to 2010 with no accompanying change in SSS, a trend that persists even when ENSO variability is removed. In contrast, larger increases in SST and SSS are evident in coral records from the equatorial Pacific Line Islands, located east of Butaritari. Taken together, the equatorial Pacific coral records suggest an overall reduction in the east-west SST and SSS gradient over the last several decades, and a recent weakening of the Walker Circulation.
dc.description.sponsorshipThis work was supported by an Australian Nuclear Science and Technology Organization Postdoctoral Fellowship (J.C.), a Natural Sciences and Engineering Research Council of Canada Discovery Grant (S.D.), a National Science Foundation Ocean Sciences Postdoctoral Fellowship (S.S.), and ARC Discovery Project grant DP1092945 (H.V.M.), and an AINSE Fellowship grant (H.V.M.).
dc.format15 pages
dc.publisherAmerican Geophysical Union (AGU)
dc.sourcePaleoceanography
dc.subjectcoral
dc.subjectgeochemistry
dc.subjectpaleoclimate
dc.subjectoxygen isotopes
dc.subjectSr/Ca
dc.subjectENSO
dc.titleEquatorial Pacific coral geochemical records show recent weakening of the Walker Circulation
dc.typeJournal article
local.identifier.citationvolume29
dcterms.dateAccepted2014-09-29
dc.date.issued2014-11
local.identifier.absfor040104 - Climate Change Processes
local.identifier.absfor040605 - Palaeoclimatology
local.identifier.ariespublicationu4027924xPUB415
local.publisher.urlhttp://sites.agu.org/
local.type.statusPublished Version
local.contributor.affiliationMcGregor, Helen V., ANU College of Physical & Mathematical Sciences, Research School of Earth Sciences, The Australian National University
local.contributor.affiliationGagan, Michael K., ANU College of Physical & Mathematical Sciences, Research School of Earth Sciences, The Australian National University
dc.relationhttp://purl.org/au-research/grants/arc/DP1092945
local.identifier.essn1944-9186
local.bibliographicCitation.issue11
local.bibliographicCitation.startpage1031
local.bibliographicCitation.lastpage1045
local.identifier.doi10.1002/2014PA002683
local.identifier.absseo960399 - Climate and Climate Change not elsewhere classified
dc.date.updated2015-12-09T11:05:01Z
local.identifier.scopusID2-s2.0-84923210504
local.identifier.thomsonID000346489000003
dcterms.accessRightsOpen Access
dc.provenancehttp://www.sherpa.ac.uk/romeo/issn/1944-9186..."Publisher's version/PDF must be used in Institutional Repository 6 months after publication." http://publications.agu.org/files/2013/03/AGU-standard-copyright-form.pdf "Permission to Deposit an Article in an Institutional Repository AGU allows authors to deposit their journal articles if the version is the final published citable version of record, the AGU copyright statement is clearly visible on the posting, and the posting is made 6 months after official publication by the AGU."
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