A brief history of climate change and conflict
The most significant determinant of impact is change in temperature, which may either increase or decrease. Precipitation patterns also change in these periods, but regional differences make it harder to know what type of impacts will occur (more on this in Chapter 3). Whether the event is a type of Hot or Cold War depends on the extant climate in the area. To conceptualize this relationship, consider how changes in temperature might affect migration in the two tension zones. Cold areas that become warmer invite immigrants, while hot areas becoming hotter push emigrants out. Of course, there will be differences in motivations for migration, whether to claim fertile land, to access renewable resources like wood or water, to seek out finite resources like gold or oil, or to obtain transit routes (see Table 2.1). The four periods cover diverse instances of natural and human interaction. Comparing and contrasting the periods and cases can reveal some general typologies for climate change and conflict. The Holocene Warming Period marked a period of intense warming that began the end of the current Ice Age. In the Medieval Climate Optimum, during the Middle Ages, a warming and favorable climate allowed human institutions to recover after the Dark Ages in Europe. In the Little Ice Age, conditions became cooler in the latter half of the second millennium. These conditions sometimes reversed gains in the medieval warm period. Finally, the current Anthropogene Warming Period, like the Holocene Warming Period, marks a return to dramatic warming conditions. The point of the following case studies is not to prove a hypothesis related to Cold Wars and Hot Wars. History and these cases are much too messy to draw one-to-one comparisons. The cases do, however, show trends that suggest how Hot and Cold Wars evolved in the past, and how the lessons from them can be meaningful in the future. Each case represents an instance where climate change, along with a variety of other intervening variables, leads to conflict.