In polar and alpine regions that are sufficiently cold, snowfall can persist from year to year and consequently can build up in layers. With time, the weight of the snow compresses the deeper snow layers to form solid ice, resulting in a sheet of ice and snow called a glacier.

Each layer of snow, which eventually becomes a layer of ice, carries with it some information about the environment and climate that existed when the snowfall occurred. By drilling down into glaciers and removing long cores of this layered ice and snow, scientists can better understand how Earth’s climate has changed over time. Read more

Complex relationships exist between water and the security of individuals, communities, nations, and the global community as a whole. The vital role of water in daily life and economic activity underscores its importance to a secure and stable world. Water resources and the provision of water services involve political decision-making, and extreme types of conflict can escalate into violence, terrorism, or war.

Gleick (2000) provides a timeline of water conflicts throughout history, categorizing them according to the basis of the conflict and the actors involved.

• State and non-state parties fight over water supplies or access to water supplies (control dispute).
• Nations use water resources or water systems as a weapon during a military action (military tool).
• State and non-state parties use water resources or water systems for political goals (political tool).
• Non-state parties use water resources or water systems as a target or tool for violence or coercion (terrorism).
• Nations use water systems as a target for military action (military target).
• State and non-state parties argue over water resources or water systems in the context of economic development (development dispute).

Military and terrorist actions are of particular concern to security experts and those who are responsible for managing water resources and water systems.  Read more

Deserts are arid regions, generally receiving less than 25 centimeters (10 inches) of precipitation a year, or regions where the potential evaporation rate is significantly greater than the precipitation. In most cases, deserts possess a high average temperature with large differences between daytime and nighttime temperatures. Arid regions can also be defined as environments in which water is the limiting factor for biosystems . This means that survival

This desert in Valley of the Tsauchab, Namibia illustrates the vegetation, desert crust, and occasionally pooled water that characterize these arid regions. Annual rainfall in Namibia’s coastal desert is 50 millimeters (about 2 inches).
of life in these regions involves a constant struggle to obtain this limited commodity and to draw the maximum benefit from it. Read more