Human influence versus natural climate variability

Abstract

This chapter discusses past climate change drivers and ecological responses in southeastern Mexico. Ancient human influence on ecosystems is evident from sediment cores. Past human activities are evident in fossil records but make the interpretation of the past climatic signals more difficult. Conversely the human signal provides important evidence for understanding the level of human impact on the climate system and ecosystems. Four sediment cores at different locations of the Yucatan Peninsula were analyzed for fossil pollen and geochemistry. Human-induced ecological change was evaluated compared to climate-driven environmental change. Fossil pollen gave a clear signal of landscape and precipitation change in the Preclassic and Classic periods. The geochemical ratios provided evidence of local and regional hydrological change. The Chumpich Lake registry reveals that the management of low forests was efficient and indicates good hydrological control in the landscape. However this evidence is different in other sites from Yucatan Peninsula with deficient erosion control. Probably due to the differential climate response in the Chumpich-Uxul region, the drought was not as drastic as in other places.