Abstract
Although Great Basin paleoclimate history has been examined for more than a century, the orbital-scale paleoclimate forcings remain poorly understood. Here we show – by a detailed phasing analysis of a well-dated stalagmite δ18O time series – that Great Basin paleoclimate is linearly related to, but lagged, the 23,000 yr precession cycle in northern hemisphere summer insolation by an average of 3240 years (−900 to 6600 yr range) over the last two glacial cycles. We interpret these lags as indicating that Great Basin climate is sensitive to and indirectly forced by changes in the cryosphere, as evidenced by fast and strong linkages to global ice volume and Arctic paleoclimate indicators. Mid-latitude atmospheric circulation was likely impacted by a northward shifted storm track and higher pressure over the region arising from decreased sea ice and snow cover. Because anthropogenic warming is expected to reduce northern hemisphere snow and ice cover, continued increase in atmospheric greenhouse gases is likely to result in warming and drying over coming centuries that will amplify a warming trend that began ~2400 years ago.
Highlights
Great Basin paleoclimate history has been examined for more than a century, the orbital-scale paleoclimate forcings remain poorly understood
Several features of the Leviathan chronology suggest that it is a reliable proxy for Great Basin climate variations: it is securely dated with 65 high-precision U-series ages; the stalagmites grew in near-surface vadose zone caves
We show that the onset of the last interglacial lagged insolation: Termination II (TII), as defined by the mid-point δ18Oivc value of −12.03‰, dates to 131,100 yr B2k (Fig. 1 and Table 1) but dates to 133,200 in NHSI
Summary
Great Basin paleoclimate history has been examined for more than a century, the orbital-scale paleoclimate forcings remain poorly understood. We show – by a detailed phasing analysis of a well-dated stalagmite δ18O time series – that Great Basin paleoclimate is linearly related to, but lagged, the 23,000 yr precession cycle in northern hemisphere summer insolation by an average of 3240 years (−900 to 6600 yr range) over the last two glacial cycles. We interpret these lags as indicating that Great Basin climate is sensitive to and indirectly forced by changes in the cryosphere, as evidenced by fast and strong linkages to global ice volume and Arctic paleoclimate indicators. We investigate the orbital-scale phasing relationships between Nevada paleoclimate and insolation forcing over the past 175,000 years, and highlight several key features of the δ18O time series that support a fast climate response to precessional-scale forcing in the Great Basin of western North America
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