20TH CENTURY CLIMATE CHANGE AND ENVIRONMENTAL RESPONSE IN THE PERUVIAN ANDES

The Cordillera Vilcanota (14°S, 71°W), a glaciated range in the Peruvian Andes is being studied by a multidisciplinary team to reveal environmental and ecological response to ongoing climatic change and resultant deglaciation of high alpine zones. The Vilcanota is renowned for the Quelccaya Ice Cap from which a 1500-year chronology of interannual climatic variation was obtained by ice core retrieval in 1983. This record has revealed abrupt regional climatic changes associated with the A.D. 1500-1900 Little Ice Age and subsequent and ongoing warming. This climate history has not been matched by a comparable environmental history, however, our data being mostly confined only to the last decades of the 20th century. We have recently discovered a previously unknown series of high-resolution aerial photographs taken in 1931 centered upon our present-day field study area. Incorporation of this unique dataset, which precisely reveals ice extent and vegetation ecotones 71 years ago, is yielding the most detailed multidecadal environmental history of an Andean range yet assembled, and this within a region exhibiting especially profound environmental response to 20th century warming.

This geoecology project integrates components in climate and climate change impacts, human land use patterns, glaciology, geology, soil science, alpine ecology, disturbance ecology, mammalogy and other animal sciences, remote sensing, cartography and GIS modeling. Our methodology is to integrate the 1931 image series with other data types through a combination of photogrammetric analysis, repeat aerial photography and field observation. We are conducting focused studies across a 5,400 m pass shown as icebound in the 1931 imagery but that is now deglaciated. This has established a widening ecological corridor between watersheds isolated for centuries. Rapid colonization by both plants and animals is ongoing across this corridor. Space-time mapping allows us to locate our comprehensive ecological field observations within an annual-decadal chronosequence of ice retreat and vegetation advance, augmenting the relevance and significance of these observations while also informing on more general geoecological responses to climatic variation.