2 - The relative importance of the different forcings on the environment in Ethiopia during the Holocene

Summary

Keywords

Ethiopia; Main Ethiopian Rift; Late Quaternary; Holocene environment; climate; volcanism; tectonics; human impact; crater lakes; palaeosoils; sediments; pollen; diatoms; radiocarbon dates; drought; rainfall variability; ENSO; deforestation; Little Ice Age

Abstarct

The environment within the Ethiopian region has been sensitive to different natural and anthropogenic factors on various timescales and during different times of the Quaternary. During the Holocene (the last 10, 000 years), the intensity of tectonics and volcanism in the Main Ethiopian Rift Valley has reduced, and their effects have been localized to marginal zones. However, climate change and variability on different timescales have been affecting the region within and outside the Rift Valley. During the twentieth century, the accelerated human impact has combined with highly variable rainfall, both on the inter-annual and inter-decadal timescales, to play a major role in limiting the availability of resources.

INTRODUCTION

Ethiopia is located in a geodynamically active zone and geographically sensitive area, Consequently, volcano-tectonism, as well as climate change and variability on different spatial and temporal scales, have affected its environment. Super-imposed on these, increasing human impact is modifying the land cover, land surface and hydrology. This chapter presents a review of the relative importance of the different environmental forcings during the Holocene (the last 10,000 years) in Ethiopia. This is a time when the major regional features of the environment, as we see them now, have been shaped.