Orbital control of western North America atmospheric circulation and climate over two glacial cycles

Abstract

The now arid Great Basin of western North America hosted expansive late Quaternary pluvial lakes, yet the climate forcings that sustained large ice age hydrologic variations remain controversial. Here we present a 175,000 year oxygen isotope record from precisely-dated speleothems that documents a previously unrecognized and highly sensitive link between Great Basin climate and orbital forcing. Our data match the phasing and amplitudes of 65°N summer insolation, including the classic saw-tooth pattern of global ice volume and on-time terminations. Together with the observation of cold conditions during the marine isotope substage 5d glacial inception, our data document a strong precessional-scale Milankovitch forcing of southwestern paleoclimate. Because the expansion of pluvial lakes was associated with cold glacial conditions, the reappearance of large lakes in the Great Basin is unlikely until ca. 55,000 years into the future as climate remains in a mild non-glacial state over the next half eccentricity cycle.

Timing and nature of the penultimate deglaciation in a high alpine stalagmite from Switzerland

“…This age estimate is in good agreement with less-precisely-dated stalagmites from Dongge Cave, China, , and appears to be broadly consistent with speleothem records from Soreq Cave (Israel) and Sofular Cave (Turkey) (Badertscher et al, 2011;Grant et al, 2012). However, speleothem records from Corchia Cave and Tana Che Urla Cave (Italy), Nevada Caves (N. America), suggest significantly older ages of 132.6 ± 1.8 and 132.0 ± 0.6 kyr BP for the midpoint of T-II (Drysdale et al, 2009;Shakun et al, 2011;Regatierri et al, 2014;Lachniet et al, 2014). Additional speleothem records covering T-II were obtained from Hoti Cave (Oman; Fleitmann et al, 2003), Mukallah Cave (Yemen; Fleitmann et al, 2011) Spannagel Cave (Austria;Holzk€ amper et al, 2005), Oregon Caves National Monument (USA;Esrek et al, 2009), several caves in the Negev (Israel; Vaks et al, 2010) and Villars Cave (France; Wainer et al, 2011), but their chronologies suffer from considerable age uncertainties and/ or reversals, and are thus not well-suited to shed further light on the timing of T-II.…”

“…8D and E). Furthermore, the d 18 O profiles of all stalagmites are remarkably similar during the entire penultimate deglaciation, as the Nevada Cave composite d 18 O record is also governed by temperature changes in the Great Basin (Shakun et al, 2011;Lachniet et al, 2014). In contrast to Schafsloch and Nevada Caves, variations in d 18 O in the Corchia and Tan ache Urla Cave records are related to fluctuations in the amount of precipitation (the so-called "amount effect") driven by changes in sea surface temperatures (SST) in the Atlantic and Mediterranean (Drysdale et al, 2009;Regattieri et al, 2014).…”

The Holocene history of the North American Monsoon: ‘known knowns’ and ‘known unknowns’ in understanding its spatial and temporal complexity

“…Asmerom et al, 2010). Similar conditions apparently occurred during the full glacial (Benson et al, 1990;Bradbury et al, 2001;Polyak et al, 2004;Lachniet et al, 2014). This southward displacement of the jet stream has been supported by some climate modelling (see below).…”

“…Asmerom et al, 2007Asmerom et al, , 2010Asmerom et al, , 2013Lachniet et al, 2014) with high-resolution Useries chronologies. At these more mid latitude locations, temperature affects the isotopic signature as well as precipitation source area and amount, but the focus has been on source area, particularly variations in the amount of winter precipitation originating in the Pacific which has a lower δ…”

Response to Comments on “Reconciliation of the Devils Hole climate record with orbital forcing”

“…18 O time series leads local dripstone records by~8 thousand years (ky), of which the latter are in agreement with orbital forcing (14)(15)(16) 230 Th ages in stratigraphic order, which had been analyzed using the most up-to-date techniques (19,20). Age-model indices (21) were~100% in all cases.…”