Climate-related response of dust flux to the central equatorial Pacific over the past 150 kyr
Global dust flux comparison. Oxygen isotope composition of the Greenland NGRIP ice core in blue (North Greenland Ice Core Project members, 2004) (a). Greenland dust flux record from NGRIP in dark green (Ruth et al., 2007) (b). Dust fluxes from the central equatorial Pacific (this study) with colors as in Figure 3 (c). Dust fluxes from the Antarctic EDC ice core in light green (Lambert et al., 2012) (e). Deuterium isotopic ratio of the Antarctic EDC ice core in light blue (Jouzel et al., 2007) (f). Selected Greenland and Heinrich stadial events labeled following Rasmussen et al., 2014. All time series on the AICC2012 age model of (Veres et al., 2013).
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This work was also presented at the 2015 Fall Meeting of the American Geophysical Union and was awarded an AGU Outstanding Student Paper Award.
Abstract:
High resolution paleoclimate records from low latitudes are critical for understanding the role of the tropics in transmitting and generating feedbacks for high-latitude climate change on glacial-interglacial and millennial timescales. Here we present three new records of 230Thxs,0-normalized 232Th-derived dust fluxes from the central equatorial Pacific spanning the last 150 kyr at millennial-resolution. All three dust flux records share the “sawtooth” pattern characteristic of glacial-interglacial cycles in ice volume, confirming a coherent response to global climate forcing on long timescales. These records permit a detailed examination of millennial variability in tropical dust fluxes related to abrupt perturbations in oceanic and atmospheric circulation. Increases in dust flux in association with at least six of the longest Greenland stadials provide evidence that abrupt, high-latitude climate oscillations influenced the atmospheric aerosol load in the equatorial Pacific, with implications for both direct and indirect effects on the tropical energy balance. Our latitudinal transect of cores captures shifts in the position of the Intertropical Convergence Zone (ITCZ) in response to variations in the interhemispheric thermal gradient associated with cooling in Greenland and bipolar seesaw warming in Antarctica. These observations demonstrate that changes in the energy and hydrologic balance of the tropics were repeated features of the penultimate deglaciation, last glacial inception and last glacial cycle, and highlight the role of the tropical atmosphere as a dynamic and responsive component of Earth’s climate system.