2012: Only relatively recently in the swirling scope of history have humans begun to wonder (and worry) about the possibility and impact of drastic climate change. On the heels of a summer of drought and extreme heat and in the destructive wake of Hurricane Sandy, the Potsdam Institute for Climate Impact Research and Climate Analytics released a report for the World Bank entitled "Turn Down Heat: Why a 4°C Warmer World Must be Avoided," which warns of potential catastrophe:
A world in which warming reaches 4°C above preindustrial levels (hereafter referred to as a 4°C world), would be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on human systems, ecosystems, and associated services...
Projections for a 4°C world show a dramatic increase in the intensity and frequency of high-temperature extremes. Recent extreme heat waves such as in Russia in 2010 are likely to become the new normal summer in a 4°C world. Tropical South America, central Africa, and all tropical islands in the Pacific are likely to regularly experience heat waves of unprecedented magnitude and duration. In regions such as the Mediterranean, North Africa, the Middle East, and the Tibetan plateau, almost all summer months are likely to be warmer than the most extreme heat waves presently experienced. For example, the warmest July in the Mediterranean region could be 9°C warmer than today’s warmest July.
c. 43 CE: Pomponius Mela, the earliest known Roman geographer, conceived of a vast belt of earth made uninhabitable by extreme temperatures. Beneath this impassable "torrid zone" dwelled people completely isolated from the Africans, Asians, and Europeans of the Northern Hemisphere. Mela's De situ orbis (A Description of the World) remained a popular geographical source throughout the Middle Ages and well into the sixeenth century. Mela's account of burning wastes and peoples divided by intemperate climes may yet prove a portentous account of the world—perhaps not the world of the first century, but of one to come:
"Whatever all this is, therefore, on which we have bestowed the name of world and sky, it is a single unity and embraces itself and all things with a single ambit. It differs in parts. Where the sun rises is designated formally as east or sunrise; where it sinks, as west or sunset; where it begins its descent, south; in the opposite direction, north.
In the middle of this unity the uplifted earth also is divided from east to west into two halves, which they term hemispheres, and it is differentiated by five horizontal zones. Heat makes the middle zone unlivable, and cold does so to the outermost ones. The remaining two zones have the same annual seasons, but not at the same time. The Antichtones inhabit one, we the other.
The chorography of the former zone is unknown because of the heat of the intervening expanse, and the chorography of the latter is now to be described.
Global warming image via Shutterstock