Abstract
Abstract. Increasing paleoclimatic evidence suggests that the Little Ice Age (LIA) was a global climate change event. Understanding the forcings and associated climate system feedbacks of the LIA is made difficult by the scarcity of Southern Hemisphere paleoclimate records. We use a new glaciochemical record of a coastal ice core from Mt. Erebus Saddle, Antarctica, to reconstruct atmospheric and oceanic conditions in the Ross Sea sector of Antarctica over the past five centuries. The LIA is identified in stable isotope (δD) and lithophile element records, which respectively demonstrate that the region experienced 1.6 ± 1.4 °C cooler average temperatures prior to 1850 AD than during the last 150 yr and strong (>57 m s−1) prevailing katabatic winds between 1500 and 1800 AD. Al and Ti concentration increases of an order of magnitude (>120 ppb Al) are linked to enhanced aeolian transport of complex silicate minerals and represent the strongest katabatic wind events of the LIA. These events are associated with three 12–30 yr intervals of cooler temperatures at ca. 1690 AD, 1770 AD and 1840 AD. Furthermore, ice core concentrations of the biogenic sulphur species MS− suggest that biological productivity in the Ross Sea polynya was ~80% higher prior to 1875 AD than at any subsequent time. We propose that cooler Antarctic temperatures promoted stronger katabatic winds across the Ross Ice Shelf, resulting in an enlarged Ross Sea polynya during the LIA.
Highlights
The Little Ice Age (LIA) is typically considered to be a Northern Hemisphere climate phenomenon characterised by alpine glacial advances and relatively cool temperatures observed between 15th to mid-19th centuries (Grove, 1988)
At 92 m depth in the ice core (1658 AD), the technique used for isotopic analysis was changed from mass spectrometry to laser spectroscopy and inter-calibration differences between the two instruments make comparison of absolute dexcess values difficult
Examination of the monthly resolution record of the last 35 yr links lithophile elements concentrations to mineral dust transport by katabatic winds, whilst d-excess and marine element concentrations are tentatively related to incursion of marine cyclones
Summary
The Little Ice Age (LIA) is typically considered to be a Northern Hemisphere climate phenomenon characterised by alpine glacial advances and relatively cool temperatures observed between 15th to mid-19th centuries (Grove, 1988). Paleoclimate records suggest that the LIA is the most recent cooling event of a series that punctuated the Holocene (Domack and Mayewski, 1999; Masson et al, 2000). This apparent oscillatory behaviour in Holocene climate has led to speculation about what role the thermohaline circulation of the world’s oceans may have played in instigating or amplifying these climate changes (Broecker, 2000; Denton and Broecker, 2008). An important tool to understand the LIA must be the acquisition and interpretation of Southern Hemisphere paleoclimate records, but few are currently available (Jones and Mann, 2004)
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