and common security threat have remained key themes of environmental security studies. However, not until Richard Ullman publishes an academic article named "Redefining Security" (1983), radical departure from the dominant security discourse haven't happened. Ullman offered the following definition of national security threat as "an action or sequence of events that (1) threatens drastically and over a relatively brief span of time to degrade the quality of life for the inhabitants of a state, or (2) threatens significantly to narrow the range of policy choices available to the government of a state, or to private, nongovernmental entities within the state". Significant other scientists onward also linked the issue of security by focusing on the role of environmental degradation in causing violent conflict. Others, while recognizing the importance of environmental problems, argued that labeling them 'environmental security' was problematic and abandoned analytical rigor for normative and emotional power. Environmental change and security Even though environmental degradation and climate change sometimes cause violent conflict within and between countries and other times not, it can weaken the national security of the state in number of profound ways. Environmental change can undermine the economic prosperity which plays big role in country's military capacity and material power. In some developed countries, and in most developing countries, natural resources and environmental services tend to be important factors for economic growth and employment rate. Income from and employment in primary sectors such as agriculture, forestry, fishing, and mining, and from environmentally dependent services like tourism, may all be adversely affected by environmental change. If natural capital base of an economy erodes, then so does the long-term capacity of its armed forces. Moreover, changes in environmental condition can exposes people to health threats, it can also undermine human capital and its well-being which are essential factors of economic development and stability of human society. Climate change also could, through extreme weather events, have a more direct impact on national security by damaging critical infrastructures such as military bases, naval yards and training grounds, thereby severely threatening essential national defense resources. Selected early literature Brown, L. 1977. "Redefining Security," WorldWatch Paper 14 (Washington, D.C.: WorldWatch Institute) Ullman, R.H. 1983. "Redefining Security," International Security 8, No. 1 (Summer 1983): 129–153. Westing, A.H. 1986. "An Expanded Concept of International Security," In Global Resources and International Conflict, ed. Arthur H. Westing. Oxford: Oxford University Press. Myers, N. 1986. "The Environmental Dimension to