Evaluating the ability of human communities and environmental systems to adapt and recover to Late Holocene climate change in the Peruvian Andes.

During the Late Holocene (last 4250 years), palaeoclimatic reconstructions from Peruvian archives (ice, marine, speleothems and lakes) have provided high-resolution records of precipitation and temperature changes, which reflect the varying influences of the ITCZ, SASM and ENSO. In the highland zone (Andes), the records indicate three distinct periods of short-term climate change: rising precipitation until AD 800, lower precipitation and higher temperatures from AD 800-1350 (Medieval Climate Anomaly), and finally increased variability from AD 1350 to the present day due to enhanced ENSO frequency. The records of human history in the Peruvian Andes suggest that these periods coincided with demographic changes (e.g. population rise, out-migration, increased mortality), development/failure of agricultural water management infrastructure (e.g. irrigation canals), and transformation of the landscape and environment (e.g. agricultural terrace construction, soil erosion). These climate and socio-economic records therefore tentatively suggest that highland communities and their food systems were at risk and may have been highly vulnerable in the past, but that the level of vulnerability may have varied through time due to changing environmental, social and economic factors. Our project will seek to characterise the importance of each these factors across time and space, and therefore evaluate the ability of these communities and systems to adapt and recover. We will address the following research questions: What was the magnitude, frequency and characteristics of each climatic event? What was the social, economic and environmental exposure that may have increased the risk to each event? How did communities and food systems anticipate, cope, resist and recover, or even fail, with each event?
The approach will be unique in the Peruvian Andes by coupling agent-based modelling with high-resolution palaeoenvironmental data. The student will use the former to analyse the relationships between environmental, social and economic factors, especially changes in demography, agricultural infrastructure, and land-use and climate variability. They will underpin the model with empirical data of land-use, fire history, landscape disturbance and climate change placed within a precise geochronological framework. They will achieve this using a mixed method approach. (1) Integration of secondary data from archaeological sites with major changes in regional socio-economic development and cultural history to enable palaeo-agent-based modelling to evaluate the ability of communities and systems (physical and biological) to adapt and recover. They will develop models in the Netlogo programming environment to assess the implications of the combination of climate changes and resource strategies for the distribution and structure of humans in the landscape. The student will use existing palaeoclimate reanalyses, in conjunction with information derived from the palaeoenvironmental records to provide climatic boundary conditions, overlain on high-resolution topography and land cover. (2) To underpin (1), the student will collect continuous, undisturbed sediment core samples from peatlands in three climatically distinct zones - Cordillera Blanca (northern), Cordillera Viuda (central), and Cordillera Huanzo (southern). Core samples have already been collected and pilot laboratory analysis demonstrates sufficiently high temporal resolution to detect millennial-centennial scale events. Laboratory analysis of the geochemical and sedimentary properties using ITRAX muXRF, X-ray particle size analysis and mineral magnetics as indicators of landscape erosion, and sub-fossil pollen grains and non-pollen palynomorphs as indicators of vegetation succession and land-use. Age modelling based on a high-resolution radiocarbon chronology using Oxcal/Bacon to enable spatial and temporal correlation of events. This will be challenging but groundbreaking research.