A 30 kyr Continuous Record of Tropical Climate Variability From a Mesoamerican Fpeleothem

Abstract:

We present one of the few records which continuously covers the last 30,000 yrs from the Mesoamerican tropics, considered to be the tropical region most exposed to climate change and subject to substantial drying in the future according to climate projections.

Our record was obtained from a speleothem which grew in the Grutas del Rey San Marcos cave in central Guatemala. Speleothems are increasingly used as terrestrial archives of past climate and environmental change because they can provide long, continuous, precisely U-series dated and high-resolution time series, and are generally unaffected by post-depositional diagenetic alteration. The stable isotope record, a proxy primarily for precipitation in the tropics, shows many of the salient features also found in Greenland ice cores, e.g. Heinrich events and the LGM. However, amplitudes, duration and timing of such anomalous periods do not always correspond to those recorded in ice cores. The Holocene shows a drying trend similar to what has been found in other climate archives. Our record will elucidate teleconnections at different time scales between the tropics and higher latitudes, which are highly relevant for the understanding of decadal to multicentennial climate variability and underlying dynamics, and to learn critical aspects of reconstructed as well as simulated pre-industrial tropical climate evolution. Information provided by our new record therefore contributes constraining our confidence in projected future regional precipitation trends and variability.