Holocene sea-surface temperature variability in the Chilean fjord region

Abstract

Here we provide three new Holocene (11–0calka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50–53°S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs except for the past ~0.6calka BP. However, they do not exhibit an early Holocene temperature optimum as registered further north off Chile and in Antarctica. This may have resulted from a combination of factors including decreased inflow of warmer open marine waters due to lower sea-level stands, enhanced advection of colder and fresher inner fjord waters, and stronger westerly winds. During the mid-Holocene, pronounced short-term variations of up to 2.5°C and a cooling centered at ~5calka BP, which coincides with the first Neoglacial glacier advance in the Southern Andes, are recorded. The latest Holocene is characterized by two pronounced cold events centered at ~0.6 and 0.25calka BP, i.e., during the Little Ice Age. These cold events have lower amplitudes in the offshore records, suggesting an amplification of the SST signal in the inner fjords.