Southwest Pacific Ocean alkenone unstaturation ratio from the Pliocene to the present Fedorov, A.V.; Burls, N.J.; Lawrence, K.T.; Peterson, L.C. Fedorov, A.V. Burls, N.J. Lawrence, K.T. Peterson, L.C. earth science/paleoclimate/paleoceanography (sample identification,null,null,null,null,paleoceanography,null,null,C,null) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,composite depth) earth science/paleoclimate/paleoceanography (depth at sample start,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (age,null,null,million years ago,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (alkenone unsaturation index Uk37 prime,sediment,null,dimensionless,null,paleoceanography,null,gas chromatography - flame ionization detection,N,null) earth science/paleoclimate/paleoceanography (depth at sample end,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (ODP 1125>LATITUDE -42.55>LONGITUDE -178.166) The climate of the tropics and surrounding regions is defined by pronounced zonal (east-west) and meridional (equator to mid-latitudes) gradients in sea surface temperature. These gradients control zonal and meridional atmospheric circulations, and thus the Earth's climate. Global cooling over the past five million years, since the early Pliocene epoch, was accompanied by the gradual strengthening of these temperature gradients. Here we use records from the Atlantic and Pacific oceans, including a new alkenone palaeotemperature record from the South Pacific, to reconstruct changes in zonal and meridional sea surface temperature gradients since the Pliocene, and assess their connection using a comprehensive climate model. We find that the reconstructed zonal and meridional temperature gradients vary coherently over this time frame, showing a one-to-one relationship between their changes. In our model simulations, we systematically reduce the meridional sea surface temperature gradient by modifying the latitudinal distribution of cloud albedo or atmospheric CO2concentration. The simulated zonal temperature gradient in the equatorial Pacific adjusts proportionally. These experiments and idealized modelling indicate that the meridional temperature gradient controls upper-ocean stratification in the tropics, which in turn controls the zonal gradient along the equator, as well as heat export from the tropical oceans. We conclude that this tight linkage between the two sea surface temperature gradients posits a fundamental constraint on both past and future climates. STUDY NOTES: Provided Keywords: paleoclimate, meridional temperature gradient, sea surface temperature, Pliocene, Pleistocene. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Fedorov, A.V. Investigator : Burls, N.J. Investigator : Lawrence, K.T. Investigator : Peterson, L.C. 2018-10-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/25310 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/fedorov2015/fedorov2015-odp1125.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/fedorov2015/fedorov2015-odp1125.txt English https://www.ncdc.noaa.gov/paleo/study/25310 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/fedorov2015/fedorov2015-odp1125.txt Fedorov, A.V., N.J. Burls, K.T. Lawrence, and L.C. Peterson2015Tightly linked zonal and meridional sea surface temperature gradients over the past five million yearsNature Geoscience8975-98010.1038/ngeo2577 START YEAR: 5012000 cal yr BP * END YEAR: 42000 cal yr BP -178.166 -42.55 -178.166 -42.55