Millennial and orbital variations of El Niño/Southern Oscillation and high-latitude climate in the last glacial period

Abstract

The El Niño/Southern Oscillation (ENSO) phenomenon is believed to have operated continuously over the last glacial-interglacial cycle. ENSO variability has been suggested to be linked to millennial-scale oscillations in North Atlantic climate during that time, but the proposals disagree on whether increased frequency of El Niño events, the warm phase of ENSO, was linked to North Atlantic warm or cold periods. Here we present a high-resolution record of surface moisture, based on the degree of peat humification and the ratio of sedges to grass, from northern Queensland, Australia, covering the past 45,000 yr. We observe millennial-scale dry periods, indicating periods of frequent El Niño events (summer precipitation declines in El Niño years in northeastern Australia). We find that these dry periods are correlated to the Dansgaard-Oeschger events--millennial-scale warm events in the North Atlantic climate record--although no direct atmospheric connection from the North Atlantic to our site can be invoked. Additionally, we find climatic cycles at a semiprecessional timescale (approximately 11,900 yr). We suggest that climate variations in the tropical Pacific Ocean on millennial as well as orbital timescales, which determined precipitation in northeastern Australia, also exerted an influence on North Atlantic climate through atmospheric and oceanic teleconnections.

Centennial-scale vegetation and North Atlantic Oscillation changes during the Late Holocene in the southern Iberia

“…4). This ratio has previously been used as an indicator of wet and dry conditions in bog areas (e.g., Turney et al, 2004). A cyclostratigraphic analysis was performed in the BdlC-01 pollen time series.…”

“…In this study we also used xerophyte pollen to elucidate climatic shifts. In addition, the widely-used Cyperaceae -Poaceae pollen ratio (C/P ratio; Cour et al, 1999;Turney et al, 2004;Mensing et al, 2007) was used as a paleoclimate proxy to record the local vegetation response to fluctuations between wetter and drier bog conditions. Alternating high pollen percentages of Cyperaceae and Poaceae suggest that the bog frequently changed between wetter (high C/P ratio) and drier (low C/P ratio) states (Jiménez- ).…”

Short-term fluctuations in vegetation and phytoplankton during the Middle Eocene greenhouse climate: a 640-kyr record from the Messel oil shale (Germany)

“…A conspicuous increase in the significance for obliquity and precession is noticeable. The spectra in c and d were calculated with software REDFIT 3.8 high-latitude and East African climate are known for the tropical Pleistocene (Trauth et al 2003;Turney et al 2004). But, sub-Milankovitch cyclicity in the Messel oil shale is part of an ongoing detailed study.…”

Rapid interhemispheric climate links via the Australasian monsoon during the last deglaciation

“…However, marine and terrestrial records of the climatic footprint of HS1 in the Southern Hemisphere sector of the Australasian monsoon are still sparse, and not entirely consistent [19][20][21][22][23][24] . Marine records of riverine input to the Flores Sea 23 and offshore of southern Papua New Guinea 22 indicate increased runoff during Northern Hemisphere cold intervals such as HS1.…”