Precipitation changes in the South American Altiplano since 1300 AD reconstructed by tree-rings

Abstract

Abstract. Throughout the second half of the 20th century, the Central Andes has experienced significant climatic and environmental changes characterized by a persistent warming trend, an increase in elevation of the 0 • C isotherm, and sustained glacier shrinkage. These changes have occurred in conjunction with a steadily growing demand for water resources. Given the short span of instrumental hydroclimatic records in this region, longer time span records are needed to understand the nature of climate variability and to improve the predictability of precipitation, a key factor modulating the socio-economic development in the South American Altiplano and adjacent arid lowlands. In this study we present the first quasi-millennial, tree-ring based precipitation reconstruction for the South American Altiplano. This annual (November-October) precipitation reconstruction is based on the Polylepis tarapacana tree-ring width series and represents the closest dendroclimatological record to the Equator in South America. This high-resolution reconstruction covers the past 707 yr and provides a unique record characterizing the occurrence of extreme events and consistent oscillations in precipitation. It also allows an assessment of the spatial and temporal stabilities of the teleconnections between rainfall in the Altiplano and hemispheric forcings such as El Niño-Southern Oscillation. Since the 1930s to present, a persistent negative trend in precipitation has been recorded in the reconstruction, with the three driest years since 1300 AD occurring in the last 70 yr. Throughout the 707 yr, the reconstruction contains a clear ENSO-like pattern at interannual to multidecadal time scales, which determines inter-hemispheric linkages between our reconstruction and other precipitation sensitive records modulated by ENSO in North America. Our reconstruction points out that centuryscale dry periods are a recurrent feature in the Altiplano climate, and that the future potential coupling of natural and anthropogenic-induced droughts may have a severe impact on socio-economic activities in the region. Water resource managers must anticipate these changes in order to adapt to future climate change, reduce vulnerability and provide water equitably to all users.

The Medieval Climate Anomaly and the Little Ice Age in the eastern Ecuadorian Andes

“…In southern Peru, a pollen record confirmed the presence of a sustained drought between 900 AD and the early 17th century (Chepstow-Lusty et al, 2009) that allowed the Incas to expand their Andean territory due to their ability to use new drought-adapted agricultural practices up to high elevations (Kuentz et al, 2012). Recently, tree-ring climate reconstructions of the last 700 yr from the central Andes also revealed a persistent drought from the 14th to the 16th century and a return to wetter conditions at the beginning of the 17th century, which was then again followed by another long-term drought (Morales et al, 2012). ENSO variability was inferred to explain these changes in moisture conditions on the Altiplano.…”

The South American monsoon variability over the last millennium in climate models

“…Recent high-resolution records from the area of the South American monsoon system (SAMS) domain have been used to reconstruct precipitation over this region. Records include speleothems (Novello et al, , 2016Kanner et al, 2013;Apaestegui et al, 2014), pollen (Ledru et al, 2013), lake sediments (Bird et al, 2011), and tree-ring reconstructions (Morales et al, 2012). reviewed currently available proxy records for the SAMS region.…”

Observatorio Ecosocial Para El Seguimiento Del Cambio Climático en Ecosistemas De Altura en La Región De Tarapacá: Propuestas, Avances Y Proyecciones

“…Tendencias recientes indican que para el altiplano el aumento es más marcado en las temperaturas, aunque para zonas costeras incluso se han observado disminuciones en ellas (Vuille et al 2015). Por el contrario, para las precipitaciones las reconstrucciones generadas mediante anillos de crecimiento de la queñoa (Polylepis tarapacana) indican que los últimos treinta años presentan una tendencia sostenida hacia la disminución, llegando a los menores niveles en los últimos 700 años (Morales et al 2012). Por su parte, las tendencias proyectadas por modelos globales no son tan claras en cuanto a cambios en la precipitación total anual respecto de los valores actuales (cambios no significativos para 2046-2065IPCC-AR5 WG1, escenario RCP4.5, 2013), aunque con modelos en mayor detalle surgen tendencias hacia la baja en las precipitaciones incluso en los escenarios más conservadores de cambio climático (i.e.…”