title: Irregular tropical glacier retreat over the Holocene epoch driven by progressive warming.
abstract: The causes and timing of tropical glacier fluctuations during the Holocene epoch (10,000 years ago to present) are poorly understood. Yet constraining their sensitivity to changes in climate is important, as these glaciers are both sensitive indicators of climate change and serve as water reservoirs for highland regions. Studies have so far documented extra-tropical glacier fluctuations, but in the tropics, glacier-climate relationships are insufficiently understood. Here we present a (10)Be chronology for the past 11,000 years (11 kyr), using 57 moraines from the Bolivian Telata glacier (in the Cordillera Real mountain range). This chronology indicates that Telata glacier retreated irregularly. A rapid and strong melting from the maximum extent occurred from 10.8 ± 0.9 to 8.5 ± 0.4 kyr ago, followed by a slower retreat until the Little Ice Age, about 200 years ago. A dramatic increase in the rate of retreat occurred over the twentieth century. A glacier-climate model indicates that, relative to modern climate, annual mean temperature for the Telata glacier region was -3.3 ± 0.8 °C cooler at 11 kyr ago and remained -2.1 ± 0.8 °C cooler until the end of the Little Ice Age. We suggest that long-term warming of the eastern tropical Pacific and increased atmospheric temperature in response to enhanced austral summer insolation were the main drivers for the long-term Holocene retreat of glaciers in the southern tropics.
authors.affiliation: Université Paris 1 Panthéon-Sorbonne-CNRS Laboratoire de Géographie Physique, 92195 Meudon, France. jomelli@cnrs-bellevue.fr
authors.forename: Vincent
authors.initials: V
authors.lastname: Jomelli
authors.forename: Myriam
authors.initials: M
authors.lastname: Khodri
authors.forename: Vincent
authors.initials: V
authors.lastname: Favier
authors.forename: Daniel
authors.initials: D
authors.lastname: Brunstein
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Ledru
authors.forename: Patrick
authors.initials: P
authors.lastname: Wagnon
authors.forename: Pierre-Henri
authors.initials: PH
authors.lastname: Blard
authors.forename: Jean-Emmanuel
authors.initials: JE
authors.lastname: Sicart
authors.forename: Régis
authors.initials: R
authors.lastname: Braucher
authors.forename: Delphine
authors.initials: D
authors.lastname: Grancher
authors.forename: Didier Louis
authors.initials: DL
authors.lastname: Bourlès
authors.forename: Pascale
authors.initials: P
authors.lastname: Braconnot
authors.forename: Mathias
authors.initials: M
authors.lastname: Vuille