Tropical Glacier and Ice Core Evidence of Climate Change on Annual to Millennial Time Scales

Abstract

Abstract. This paper examines the potential of the stable isotopic ratios, 18 0/ 16 0 (8180ice) and 2H/ 1 H (8Dice), preserved in mid to low latitude glaciers as a tool for paleoclimate reconstruction. Ice cores are particularly valuable as they contain additional data, such as dust concentrations, aerosol chemistry, and accumulation rates, that can be combined with the isotopic information to assist with inferences about the regional climate conditions prevailing at the time of deposition. We use a collection of multi-proxy ice core histories to explore the 8 18 0-c1imate relationship over the last 25,000 years that includes both Late Glacial Stage (LGS) and Holocene climate conditions. These results suggest that on centennial to millennial time scales atmospheric temperature is the principal control on the 8180ice of the snowfall that sustains these high mountain ice fields.Decadally averaged 8180ice records from three Andean and three Tibetan ice cores are composited to produce a low latitude 8180ice history for the last millennium. Comparison of this ice core composite with the Northern Hemisphere proxy record (1000-2000 A.D.) reconstructed by Mann et al. (1999) and measured temperatures (1856-2000) reported by Jones et al. (1999) suggests the ice cores have captured the decadal scale variability in the global temperature trends. These ice cores show a 20th century isotopic enrichment that suggests a large scale warming is underway at low latitudes. The rate of this isotopically inferred warming is amplified at higher elevations over the Tibetan Plateau while amplification in the Andes is latitude dependent with enrichment (warming) increasing equatorward. In concert with this apparent warming, in situ observations reveal that tropical glaciers are currently disappearing. A brief overview of the loss of these tropical data archives over the last 30 years is presented along with evaluation of recent changes in mean 8180ice composition. The isotopic composition of precipitation should be viewed not only as a powerful proxy indicator of climate change, but also as an additional parameter to aid our understanding of the linkages between changes in the hydrologic cycle and global climate.

Alkenone‐based reconstruction of late‐Holocene surface temperature and salinity changes in Lake Qinghai, China

“…The inset is a satellite image of Lake Qinghai, where our sediment site is indicated. [Thompson et al, 2003;Yao and Thompson, 1992], (c) alkenone-based temperature record from Lake Qinghai, using the Chu et al…”

“…It is one of the places that will exhibit an unambiguous climate response to anticipated greenhouse warming [Hansen et al, 1988]. Ice core records from this region have already witnessed a unanimous warming trend in the 20th century [Thompson et al, 1993[Thompson et al, , 2003. Precipitation in this region is strongly influenced by Asian monsoons that are driven by the thermally induced pressure gradient between ocean and land.…”

“…[3] Holocene temperature and hydrological oscillations in this region have been reconstructed from ice cores, tree rings and lake sediments [Ji et al, 2005;Thompson et al, 2003;Yang et al, 2002]. However, most proxies previously used to study the climate of the Qinghai-Tibetan region are either qualitative in nature or confounded by multiple climatic factors.…”

Late Holocene environmental change and human impact inferred from three soil monoliths and the Laguna Zurita multi-proxi record in the southeastern Ecuadorian Andes

“…A.D. 1140 to 1250, coeval with the 'Medieval Warm Period', and a cooler period between ca. A.D. 1300 and 1850, correlated with the 'Little Ice Age' in the northern hemisphere (Thompson et al 2003). Palaeolimnological records from Lake Titicaca (Bolivia) show a wet period from ca.…”

“…Examples of these are from Lake Ayauch in the southeastern part of Ecuadorian Amazonia (Bush and Colinvaux 1988), from Rio Napo (Yasuni National Park) in the northwestern Amazon basin of Ecuador (Colinvaux et al 1988a;Weng et al 2002), from Lake Yambo at the Inter-Andean plateau of Ecuador (Colinvaux et al 1988b), from Lake Surucucho in the central Ecuadorian Andes (Colinvaux 1997), from the Colombian Cauca Valley (Berrio et al 2002), from Laguna de Chochos in the eastern Peruvian Andes (Bush et al 2005), from the Junin area in the central Peruvian Andes (Hansen et al 1984(Hansen et al , 1994, from Quelccaya ice-core in the central Peruvian Andes (Thompson et al 1984(Thompson et al , 1986(Thompson et al , 2003, from Lake Titicaca and the surrounding BolivianPeruvian Altiplano (Binford et al 1997) and from the Cuzco region in Peru (Chepstow-Lusty et al 2003). Locations of greater interest for this study are shown in Fig.…”