Maria del Rosario Prieto

A Chronology of El Niño Events from Primary Documentary Sources in Northern Peru

The authors present a chronology of El Nino (EN) events based on documentary records from northern Peru. The chronology, which covers the period 1550-1900, is constructed mainly from primary sources from the city of Trujillo (Peru), the Archivo General de Indias in Seville (Spain), and the Archivo General de la Nacion in Lima (Peru), supplemented by a reassessment of documentary evidence included in previously published literature. The archive in Trujillo has never been systematically evaluated for information related to the occurrence of El Nino-Southern Oscillation (ENSO). Abundant rainfall and river discharge correlate well with EN events in the area around Trujillo, which is very dry during most other years. Thus, rain and flooding descriptors, together with reports of failure of the local fishery, are the main indicators of EN occurrence that the authors have searched for in the documents. A total of 59 EN years are identified in this work. This chronology is compared with the two main previous documentary EN chronologies and with ENSO indicators derived from proxy data other than documentary sources. Overall, the seventeenth century appears to be the least active EN period, while the 1620s, 1720s, 1810s, and 1870s are the most active decades. The results herein reveal long-term fluctuations in warm ENSO activity that compare reasonably well with low-frequency variability deduced from other proxy data.

Atmospheric Circulation Changes in the Tropical Pacific Inferred from the Voyages of the Manila Galleons in the Sixteenth–Eighteenth Centuries

Historical accounts of the voyages of the Manila galleons derived from the Archivo General de Indias (General Archive of the Indies, Seville, Spain) are used to infer past changes in the atmospheric circulation of the tropical Pacific Ocean. It is shown that the length of the voyage between Acapulco, Mexico, and the Philippine Islands during the period 1590–1750 exhibits large secular trends, such that voyages in the middle of the seventeenth century are some 40% longer than those at the beginning or at the end of the century, and that these trends are unlikely to have been caused by societal or technological factors. Analysis of a series of “virtual voyages,” constructed from modern wind data, indicates that sailing time to the Philippines depended critically on the strength of the trade winds and the position of the western Pacific monsoon trough. These results suggest that the atmospheric circulation of the western Pacific underwent large, multidecadal fluctuations during the seventeenth century.

Reconstrucción de la cobertura de la vegetación y uso del suelo hacia 1550 y sus cambios a 2007 en la ecorregión de los bosques valdivianos lluviosos de Chile (35º - 43º 30´ S)

SUMMARY The estimation of the forest and vegetation cover in the Valdivian Rainforest Eco-region (35o − 43o30´ S) of Chile in the PreEuropean period emerges as a relevant scientific question due to its implications for forest conservation and for the improvement of the understanding of the patterns and dynamics of human settlement. This study uses a transdisciplinary approach integrating information from historical documents, archaeological evidence and the relationship of present vegetation with environmental variables. From this analysis we developed the first reconstruction of the forest and vegetation in the Valdivian Rainforest Eco-region circa 1550 (1:500.000 scale map). Our results indicate that native forests covered 11.3 million ha ca. 1550 at the Spanish conqueror arrival, decreasing to 5.7 million ha in 2007 (50.4 % of the original area). This reduction is due to the conversion of native forests to pasturelands, shrublands and agriculture land and, since 1974, forest plantations of exotic species. This study shows the need to continue developing transdisciplinary research, which integrates historical, archaeological and biophysical (potential vegetation, pollen analysis and dendrochronology) data to improve the understanding of changing forest and vegetation cover under climatic fluctuations and human influences during the last 450 years.

Continental-Scale Temperature Variability during the Past Two Millennia: Supplementary Information

Past global climate changes had strong regional expression. To elucidate their spatio-temporal pattern, we reconstructed past temperatures for seven continental-scale regions during the past one to two millennia. The most coherent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend, which ended late in the nineteenth century. At multi-decadal to centennial scales, temperature variability shows distinctly different regional patterns, with more similarity within each hemisphere than between them. There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age, but all reconstructions show generally cold conditions between ad 1580 and 1880, punctuated in some regions by warm decades during the eighteenth century. The transition to these colder conditions occurred earlier in the Arctic, Europe and Asia than in North America or the Southern Hemisphere regions. Recent warming reversed the long-term cooling; during the period ad 1971–2000, the area-weighted average reconstructed temperature was higher than any other time in nearly 1,400 years.

Climate anomalies and epidemics in South America at the end of the Colonial Period

Climate is one of the most of influential natural factors on society and economy. One of the consequences of climate anomalies is the emergence of diseases and epidemics, especially in agrarian societies. The current concern with long-term climate change and its measurable consequences on health and disease gives new relevance to the question of how agrarian societies fared during sharp droughts and other climatic hardships, especially those subject to the disruptive processes of colonization. Not many studies have been done in Latin America that relate climate, epidemics and mortality from a historical perspective. This paper explores the association between climatic anomalies, epidemic events, and native demographic decline in the Alto Peru region in the highlands of Bolivia, in the late eighteenth and early nineteenth century. Studies of historic climatology indicate that adverse climate events became more frequent in the southern areas of South America during these centuries. There were extreme oscillations in precipitation, especially beginning in the 1750’s which significantly impacted the largest group of people in late colonial Alto Peru: the indigenous population, whose vulnerability increased in face of local climatic anomalies and the resulting epidemiological risk. Both the quantitative and the qualitative analysis show associations between climatic and epidemic events.

Ship logbooks help analyze pre-instrumental climate

The Climatological Database for the Worlds Oceans: 1750–1854 (CLIWOC) project, which concluded in 2004, abstracted more than 280,000 daily weather observations from ships logbooks from British, Dutch, French, and Spanish naval vessels engaged in imperial business in the eighteenth and nineteenth centuries. These data, now compiled into a database, provide valuable information for the reconstruction of oceanic wind field patterns for this key period that precedes the time in which anthropogenic influences on climate became evident. These reconstructions, in turn, provide evidence for such phenomena as the El Nino-Southern Oscillation and the North Atlantic Oscillation. Of equal importance is the finding that the CLIWOC database—the first coordinated attempt to harness the scientific potential of this resource [Garcia-Herrera et al., 2005]—represents less than 10 percent of the volume of data currently known to reside in this important but hitherto neglected source.

Early meteorological records from Latin-America and the Caribbean during the 18th and 19th centuries

This paper provides early instrumental data recovered for 20 countries of Latin-America and the Caribbean (Argentina, Bahamas, Belize, Brazil, British Guiana, Chile, Colombia, Costa Rica, Cuba, Ecuador, France (Martinique and Guadalupe), Guatemala, Jamaica, Mexico, Nicaragua, Panama, Peru, Puerto Rico, El Salvador and Suriname) during the 18th and 19th centuries. The main meteorological variables retrieved were air temperature, atmospheric pressure, and precipitation, but other variables, such as humidity, wind direction, and state of the sky were retrieved when possible. In total, more than 300,000 early instrumental data were rescued (96% with daily resolution). Especial effort was made to document all the available metadata in order to allow further post-processing. The compilation is far from being exhaustive, but the dataset will contribute to a better understanding of climate variability in the region, and to enlarging the period of overlap between instrumental data and natural/documentary proxies.

Fuentes documentales para el estudio del clima en la región sur-austral de Chile (40º - 51º S) durante los últimos siglos

Frente a la importancia que han adquirido durante los ultimos anos los estudios climaticos, sumado a la necesidad de encontrar nuevas fuentes que permitan elaborar registros cada vez mas completos e integrados sobre el clima del pasado, complementando asi lo que ya se esta haciendo a traves del estudio de anillos de arboles, testigos de hielo y sedimentos lacustres, se ha considerado que la documentacion historica, generada a partir de la llegada de los espanoles al continente sudamericano, puede entregar valiosa informacion sobre diversos fenomenos meteorologicos, permitiendo elaborar registros temporales mas extensos de dichos eventos. Es por ello que en este trabajo se describen y, en la medida de lo posible, se analizan, las principales fuentes documentales para la reconstruccion del clima en la region sur de Chile (40 - 51o S) durante los ultimos 450 anos, dando cuenta de la forma en que se generaron, el tipo de informacion que pueden entregar y los lugares donde se conservan. Los registros climaticos provienen de cronicas, relatos de viajeros, informes de las autoridades de los gobiernos locales, naturalistas y cientificos, entre otros, y que han sido conservados y publicados en archivos publicos, diarios y revistas, asi como mapas antiguos, fotografias, dibujos y otros soportes graficos mas recientes. Esta investigacion formo parte de proyectos interdisciplinarios cuyo objetivo fue estudiar la historia ambiental y los cambios climaticos ocurridos en esa region desde distintas perspectivas paleoclimaticas, tales como la dendrocronologia y la glaciologia.