Hydrologic and temperature variability at Lake Titicaca over the past 50,000 years
Abstract
The Bolivian Altiplano has been the focus of many paleoclimate studies due to the important role it plays in the South American climate system. Although the timing of climate shifts in this region is relatively well known, the magnitudes of hydrologic versus temperature changes remain poorly quantified. Here we apply hydrogen isotope analysis (δD) of terrestrial leaf waxes and the TEX86 temperature proxy in sediments from Lake Titicaca to reconstruct hydrologic and temperature variability over the past 50,000 years. Our record reveals that the Altiplano underwent a major climate shift during the last deglaciation, reflected in a ~70-80% enrichment in leaf wax δD at the onset of the Holocene. Using the global isotope-temperature relationship for meteoric water, only 25-40% of this enrichment can be explained by the 4-5°C deglacial warming shown by the TEX86 proxy, indicating that precipitation was significantly reduced (and evaporation/evapotranspiration increased) during the Holocene. Further, the timing of these hydrologic and temperature changes was asynchronous during the transition from a cold and wet glacial state to a warm and dry Holocene. The major hydrologic shift recorded by leaf wax δD occurred around ~11-12 ka, consistent with Northern Hemisphere deglacial patterns, whereas TEX86 data indicate that rapid warming began much earlier, more typical of a Southern Hemisphere deglacial pattern. Within the late glacial and Holocene mean climate states, however, there is evidence of synchronous hydrologic and temperature variability on millennial timescales. This study demonstrates that climate on the Altiplano was controlled by the interaction of local and remote forcing on a range of timescales.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMPP21A1780F
- Keywords:
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- 1041 GEOCHEMISTRY / Stable isotope geochemistry;
- 1616 GLOBAL CHANGE / Climate variability;
- 1637 GLOBAL CHANGE / Regional climate change