Human history mirrors the history of climate change. Human origins, for example, can be traced to five million years ago when the climate of East Africa became progressively hotter and drier. This caused the lush tropical jungles to disappear and be replaced by arid plains and savannahs. Our pre-human ancestors learned to exploit those new ecosystems by gathering the seed-bearing grasses, nuts, and tubers that thrived in these semi-arid conditions. Also, by foraging in the heat of the day, proto-humans could minimize unwelcome contact with nocturnal predators.Looking at history in light of climate change is not only scientififically interesting, it is also a great way to tell the story of humanity’s past. Hannibal’s crossing of the Alps to invade Roman Italy in the winter of 218 CE, for example, was made possible by the warm temperatures that prevailed in Europe during the Roman Warm Period (300 BCE-400 CE). The Viking Age of Expansion (750-1100 CE) can be traced to a
Scandinavian population explosion made possible by the Medieval Warm Period (750 –1300 CE). Conversely, the famine that led to the Russian Time of Troubles (1600-1613 CE) was caused by a dramatic global cooling event that followed the explosion of the super-volcano Huaynaputina in Peru. In the same vein, the outcome of the Battle of Waterloo that led to Napoleon’s final defeat turned on the unusually cool, wet summer of 1815 in Europe caused by the explosion of the Tambora volcano in Indonesia.

The fourteen chronologically organized chapters of this book tell how many historical events—the agricultural revolution and the beginnings of cities (2,400 BCE), the rise and fall of the Western Roman Empire (300 BCE to 400 CE), the cultural renaissance in Europe during the Medieval Warm Period (750 – 1300 CE), the development of the modern atmospheric and geologic sciences due to the 1883 CE explosion of Krakatoa in Indonesia—were influenced by climate change. Finally, recognizing how climate
change has affected human societies in the past can provide useful insight as to how we can deal with climate change in the future.