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Paleoclimate reconstructions suggest distinctive changes in the El Nino–Southern Oscillation (ENSO), the dominant mode of tropical climate variability, over the last glacial cycle and throughout the Holocene. However, to the best of our knowledge, no studies provide parallel reconstructions of warm (El Nino) and cold (La Nina) phase variability, thus precluding distinction between variations in ENSO activity and the mean state of the tropical Pacific. Here we provide the first such records, generated using molecular organic geochemical proxies in a sediment core from the Peru margin region. The opposing influences of El Nino and La Nina on coastal upwelling and phytoplankton community structure produce distinct sedimentary sterol records describing the evolution of each ENSO phase. We document changes in surface ocean productivity on the Peru margin over the past 16 ka that indicate enhanced La Nina–like conditions alone during deglaciation, but concomitant increases in both El Nino and La Nina activity during the past 2 ka. We propose that the preponderance of La Nina–like conditions prior to 11.5 ka reflects the influence of waning glacial boundary conditions. By contrast, warm and cold phase covariability during the late Holocene suggests centennial-scale changes in ENSO activity, rather than the Pacific mean state, driven by tropical insolation.

During the last deglaciation (ca. 21–10 ka), freshening of the North Atlantic surface likely caused reductions in Atlantic meridional overturning circulation (AMOC); the mechanisms related to AMOC recovery remain poorly understood. Here we present three new deglacial surface temperature and δ18Oseawater (δ18Osw) reconstructions from the western subtropical North and South Atlantic. Similarities to tropical Caribbean and western Atlantic δ18Osw records suggest that a salty surface water mass accumulated in the western Atlantic from 27°S to 33°N during periods of reduced AMOC. However, δ18Osw decreases led deep AMOC resumption by hundreds of years. We suggest that the northward export of salt previously trapped in the western Atlantic resulted in the early establishment of a shallow overturning circulation that eventually culminated in deep AMOC resumption, implying that AMOC may constitute a self-limiting system.

We use geochemical data from a sediment core in the shallowsilled and intermittently dysoxic Kau Bay in Halmahera (Indo nesia, lat 1°N, long 127.5°E) to reconstruct century-scale climate variability within the Western Pacifi c Warm Pool over the past ~3500 yr. Downcore variations in bulk sedimentary δ 15 N appear to refl ect century-scale variability in basin ventilation, attributed to changes in oceanographic conditions related to century-scale fl uctuations in El Nino Southern Oscillation (ENSO). We infer an increase in century-scale El Nino activity beginning ca. 1700 yr B.P. with peaks in El Nino activity ca. 1500 yr B.P., 1150 yr B.P., and ca. 700 yr B.P. The Kau Bay results suggest that there was diminished ENSO amplitude or frequency, or a departure from El Nino–like conditions during the Medieval Warm Period, and distinctive, but steadily decreasing, El Nino activity during and after the Little Ice Age.

Paired planktic foraminiferal δ 18 O and Mg/Ca data reveal trends of increasing temperatures (~3 °C) and salinities in the subpolar North Atlantic over the course of the Holocene, which were punctuated by abrupt events. The trends likely refl ect an insolation-forced northward retreat of the boundary between polar and North Atlantic subsurface waters. The superimposed variability does not appear to be periodic, but tends to recur within a broad millennial band. The records provide convincing evidence of open-ocean cooling (nearly 2 °C) and freshening during the 8.2 ka event, and suggest similar conditions at 9.3 ka. However, the two largest temperature oscillations in our record (~2 °C) occurred during the past 4 k.y., suggesting a recent increase in temperature variability relative to the mid-Holocene, perhaps in response to neoglaciation, which began at about this time.

We present the first detailed record of Holocene climate variation from Icelandic eolian soil deposits. Seven cold and windy episodes occurred in Iceland during the past 10 k.y., including the well-documented Little Ice Age (0.6‐0.1 ka) and the 8.2 ka event. These windy events are associated with enhanced drift-ice discharge into the North Atlantic, and several are associated with evidence for cold and windy climate in central Greenland and diminution of deep-water formation in the North Atlantic. Although the Arctic Oscillation‐North Atlantic Oscillation (AO‐NAO) has been invoked to explain other climate teleconnections in the North Atlantic, our paleorecord of windiness in Iceland is not consistent with a persistent negative phase of the AO‐NAO.

Magnesium/calcium (Mg/Ca) ratios of foraminiferal shells from a sediment core from the northern South China Sea, a semi-enclosed basin in the western tropical Pacific, document variations in sea-surface temperature (SST) during the past 145 k.y. Glacial SSTs were 4 °C colder than interglacial SSTs. During the last deglaciation, most of the warming was accomplished in a single abrupt step after continental ice-sheet decay had already begun, but warming and ice-sheet demise were nearly synchronous during the penultimate deglaciation. Abrupt SST changes of the past 15 k.y. were apparently synchronous with events in East Asian monsoon rainfall, suggesting that variations in monsoon winds and their influence on surface circulation of the western Pacific exerted a strong control on northern South China Sea SSTs. We suggest that this link persisted for the previous 130 k.y., during which time orbital-scale 2-3 °C SST changes and several small (≤2 °C) abrupt SST events occurred in the northern South China Sea. The similar timing of northern South China Sea SST, on a benthic δ 1 8 O time scale, to a well-dated speleothem record from eastern China suggests that the demise of ice sheets associated with the penultimate deglaciation did not precede Northern Hemisphere summer insolation increase. Our results suggest that surface waters had higher δ 1 8 O values during times of strong summer monsoon than during times of weak monsoon, likely reflecting a redistribution of 1 8 O-depleted rainfall from land during times of strong summer monsoons, to the western Pacific during times of weaker summer monsoons.