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Sea surface and high-latitude temperature sensitivity to radiative forcing of climate over several glacial cycles

Rohling, Eelco; Medina-Elizalde, M; Shepherd, J.G.; Siddall, M; Stanford, J D

Description

Acompilation is presented of global sea surface temperature (SST) records that span around one glacial cycle or more, and it is compared with changes in the earth's radiative balance over the last 520 000 years, as determined from greenhouse gas concentrations, albedo changes related to ice sheet area and atmospheric dust fluctuations, and insolation changes. A first scenario uses global mean values for the radiative changes, and a second scenario uses zonal means for 10° latitude bands for a...[Show more]

dc.contributor.authorRohling, Eelco
dc.contributor.authorMedina-Elizalde, M
dc.contributor.authorShepherd, J.G.
dc.contributor.authorSiddall, M
dc.contributor.authorStanford, J D
dc.date.accessioned2015-12-13T22:39:56Z
dc.identifier.issn0894-8755
dc.identifier.urihttp://hdl.handle.net/1885/78004
dc.description.abstractAcompilation is presented of global sea surface temperature (SST) records that span around one glacial cycle or more, and it is compared with changes in the earth's radiative balance over the last 520 000 years, as determined from greenhouse gas concentrations, albedo changes related to ice sheet area and atmospheric dust fluctuations, and insolation changes. A first scenario uses global mean values for the radiative changes, and a second scenario uses zonal means for 10° latitude bands for a more regionally specific perspective. On the orbital time scales studied here, a smooth increase of SST response from the equator to high latitudes is found when comparison is made to global mean radiative forcing, but a sharply "stepped" increase at 20°-30° latitude when comparingwith themore regionally specific forcings. Themean global SST sensitivities to radiative change arewithin similar limits for both scenarios, around 0.860.4°C(W m-2)-1. Combinedwith previous estimates of 1.3-1.5 times stronger temperature sensitivity over land, this yields an estimate for global climate sensitivity of 0.85 (20.4/10.5)°C (W m-2)-1, close to previous estimates. If aerosol (dust) feedback were to be considered as a fast feedback, then the estimated central value for SST sensitivity would change to;0.95°C (Wm-2)-1 and that for global climate sensitivity to;1.05°C (Wm-2)-1. The zonal-mean scenario allows an assessment of (long-term) "normalized amplification" for Greenland andAntarctic temperature sensitivities, which is the ratio of temperature sensitivity for those sites relative to the global mean sensitivity, normalized per watt per meter squared of radiative change. This ratio is found to be 0.9 (-0.2/+0.6) and 1.4 (-0.4/+1.1) for Greenland and Antarctica, respectively. Given its value close to 1 for Greenland, but that larger Arctic amplification on shorter time scales due to fast sea ice albedo processes cannot be excluded, it is suggested that current high Arctic sensitivity is mainly due to sea ice albedo feedback processes and may decrease considerably if and when the Arctic sea ice cover has been eliminated. The normalized amplification value of 1.4 for Antarctica supports previous reconstructions of polar amplification in that region. The authors propose that this amplified response resulted fromapproximately threefold glacial-interglacial changes in the area of sea ice cover around Antarctica.
dc.publisherAmerican Meteorological Society
dc.rightsAuthor/s retain copyright
dc.sourceJournal of Climate
dc.subjectKeywords: Albedo; Arctic; Glaciation; Radiative forcings; Sea surface temperature (SST); Amplification; Atmospheric radiation; Atmospheric temperature; Estimation; Glacial geology; Sea ice; Solar radiation; Temperature; Climate change; aerosol; albedo; climatology; Albedo; Arctic; Glaciation; Radiative forcing; Sea ice; Sea surface temperature; Temperature
dc.titleSea surface and high-latitude temperature sensitivity to radiative forcing of climate over several glacial cycles
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume25
dc.date.issued2012
local.identifier.absfor040605 - Palaeoclimatology
local.identifier.ariespublicationf5625xPUB6707
local.type.statusPublished Version
local.contributor.affiliationRohling, Eelco, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationMedina-Elizalde, M, University of Southampton
local.contributor.affiliationShepherd, J.G., University of Southampton
local.contributor.affiliationSiddall, M, University of Bristol
local.contributor.affiliationStanford, J D, University of Southampton
local.bibliographicCitation.issue5
local.bibliographicCitation.startpage1635
local.bibliographicCitation.lastpage1656
local.identifier.doi10.1175/2011JCLI4078.1
local.identifier.absseo960399 - Climate and Climate Change not elsewhere classified
dc.date.updated2016-02-24T09:30:44Z
local.identifier.scopusID2-s2.0-84856163442
dcterms.accessRightsOpen Access
CollectionsANU Research Publications

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