Human and climatically induced environmental change in the Mediterranean during the Medieval Climate Anomaly and Little Ice Age: A case from central Italy

Abstract

Abstract Within the Anthropocene, human activities can play a major role in environmental change. Identifying human-caused landscape change is challenging, however, and requires combining high-resolution physical proxies with detailed historical records from the same locality. In this study we demonstrate that paleoenvironmental change is the complex result of both human activity and climatic variation. We use pollen and geochemical analyses from lake sediments in central Italy along with archival records to analyze landscape change for the last 1400 years, including the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Between ∼870 and 925 AD deforestation coincided with intensification of agriculture associated with development of monastic estates that exploited increasingly larger land holdings as well as new settlement patterns in higher-elevation defensible locations (incastellamento). Above average temperatures probably allowed high elevation settlements to persist throughout the MCA, though social trends played a large role in the conversion of uplands into an agro-pastoral landscape. Cool temperatures and increased precipitation at the beginning of the LIA, ∼1400 AD, combined with population loss to plague of >50 percent overwhelmed the technical capabilities of the population leading to abandonment of high elevation settlements and persistent flooding of the valley. The landscape rapidly reforested and the plain reverted to wetland. In 1601, during one of the coldest periods of the LIA, new hydrologic technology allowed the community to drain the wetlands and successfully mitigate the impacts of climate change. Despite increased LIA precipitation, the basin was steadily reclaimed and converted to agriculture by 1750 AD.