The Horn of Africa is a biodiversity hot spot, and likely comprised refugia in the distant and recent past. For millennia, rainfall capture in the Horn has fueled the development of complex economies and civilizations, from homegrown highland polities to others as distant as the Indian Ocean coast and the Nile delta. Climates and environments of the Horn are therefore of immense significance to the human past, present, and future. Despite this, our understanding of the past changes in highland climates and environments, and the circulation patterns that would have affected them, is only in a preliminary stage. This makes it difficult for archaeologists to rigorously assess the relations between past environments and human demography, technology, and behavior. In this chapter, we seek to combine insights from archaeology, ethnobotany, botany, ecology and paleoenvironmental sciences to raise awareness of the complex factors shaping climate, environment, and ultimately human behavior within and beyond the Horn. We hope these perspectives lay a foundation for productive future interdisciplinary collaboration, eventually leading to the construction and comparison of many local paleoenvironmental sequences, the ability to analyze changes operating at different chronological and geographical scales, and a better understanding of their causes and consequences.