William I. Henriquez Gonzalez
PhD Candidate in Palynology
Climate reconstruction based on multi-proxy records from New Zealand and Patagonia since the last glacial-interglacial transition
Project Aim & Description
The Southern Westerly Winds (SWW) directly influence climate system dynamics at global and hemispheric scale. Shifts in intensity and latitudinal position of the SWW have been proposed as a trigger of rising CO2 in the atmosphere as well as influencing hydrological balance and fire occurrence in the Southern Hemisphere mid- latitudes (SHML) during the last glacial-interglacial cycle (Toggweiler et al, 2006, Whitlock et al., 2007, Lamy et al, 2010). Nevertheless, understanding of hemisphere-wide SWW behaviour is limited by; i) a lack of information about SWW-shifts in the past and ii) a paucity of records at temporal- and geographical-scales that enable hemispheric comparison. Southern New Zealand (SNZ) and its Subantarctic Islands (SNZSI; 45°-52°S), along with western Patagonia (WP; 41°-56°S) in southern South America (SSA), are key regions for monitoring past variations of the SWW as both areas are located within the permanent SWW-zone of influence. Here, I will develop a high-resolution multi proxy study of the SWW system by analysing pollen, charcoal and chironomids from sedimentary records from two sites in SNZSI (46° and ~52°S) and two in WP (~44° and 52°S) to reconstruct vegetation, limnologic, fire and climate history during the last ~17,500 years. This study is the first attempt at reconstructing hemispheric shifts of the SWW at multi-millennial and centennial scale trend by developing high-resolution well dated palaeoenvironmental multi proxy records from areas north and south of the maximum SWW-zone flow (~50°S). Specifically, I will evaluate and test their hypothetical role in climate change, rising atmospheric CO2 and impacting on terrestrial ecosystem across a broad latitudinal range of the SHML since the last glacial-interglacial transition.