Quantifying responses to abrupt climate change in the Andes, South America: Empirical data and model synergies

In South America, more than 80% of the population is reliant on water supplies from mountainous areas for drinking water and agriculture. The main source of this water discharge is stored in mountain glaciers, which are known to be retreating at an unprecedented rate due to climate change. The severity of this problem is highlighted by the fact that once the glacier at the top of Mt Kilimanjaro in Africa has melted, all of the world's tropical glaciers will be located in the Andes (Kaser, 1999), mainly in Bolivia or Peru. Thus, mountain glaciers are important water sources in the dry, seasonal upland environments, but are also a very sensitive measure of present day and future climate change. These glaciers in turn feed upland Andean lakes and mires making them very sensitive repositories of climate change, and associated changes in the environment, including land-use. .

Therefore, Andean lakes and mires in the Peruvian Andes provide an opportunity to explore the history of climate change and its impact on the environment, and to provide an important palaeo-analogue for future scenarios. A number of archaeological, palaeoclimatic and palaeoenvironmental studies in the Andes have already highlighted the possible connection between past climate fluctuations, and significant cultural expansion and collapse, and associated changes in economic and socio-political structures, mainly over the last 2000 years. However, the relationship remains unclear, and there is a need for much higher spatial and temporal resolution studies before these data are useful in future scenarios, especially with respect to issue surrounding water availability and management.

Highland Andean environments are thus the ideal natural laboratory to test the sensitivity of various climate and environmental proxies, and the nature and timing of human responses to climate change. In addition, the upland Andean systems have been an important agricultural base for human communities for 1000's of years making them particularly important for the future where food security and demand for viable agricultural land are key.

Aim: This project aims to integrate isotope and palaeoecological data with quantitative modelling to determine the impact of pre-Columbian climate and environmental change on land use and human occupation for the Peruvian Andes.

In the last 15 years techniques for obtaining empirical climate and environmental reconstruction data has become increasingly available. We are now in a position to be able to collect time-integrated materials (lake cores, peat, mire and cave deposits) that can be dated accurately, and contain a range of environmental and climatic markers and fingerprints. However, until now these proxies have largely been investigated in isolation or occasionally as a combination of components. This studentship application will bring together data from organic geochemistry (lipid, faecal and bile biomarkers), palaeoecology (non-pollen palynomorphs from animals), inorganic geochemistry (heavy and light stable isotopes) and ancient DNA from upland Andean lake and mire systems to explore the connections between human occupation and agriculture in response to past climate changes. Two new sites will be cored in upland lakes from Peru (Chillón and Urubamba Valleys) and analysed for multi-proxy signals above and added to singular records from existing core material available on the NOAA palaeoclimate database (https://www.ncdc.noaa.gov/). These environmental and climatic markers will be used in conjunction with the latest climate models to offer predictions regarding key climate and environment indicators. A predictive geographical-based model (built in ArcGIS ModelBuilder) will then be used to combine all the data together to produce time-sliced geographical outputs of environmental and climate sensitivity which will be useful for coping with future climate change.