NASA EXPLAINS DUST BOWL DROUGHT. NASA scientists have an explanation for one of the worst climatic events in the history of the United States, the Dust Bowl drought, which devastated the Great Plains and all but dried up an already depressed American economy in the 1930's.
The short run [in economics] is a period of time in which the quantity of at least one input is fixed and the quantities of the other inputs can be varied. The long run is a period of time in which the quantities of all inputs can be varied.
Scarcity is the overarching theme of all economics. It sounds negative, and it is one of the reasons economics is referred to as the dismal science, but it simply means that choices have to be made.