"Global warming is no longer a theory being disputed by political interests, but an established scientific consensus. The possible effects range from events as drastic as a hydrothermal shutdown of the Gulf Stream—meaning a much colder Europe with much-reduced agriculture—to desertification of major world crop-growing areas, to the invasion of temperate regions by diseases formerly limited to the tropics, to the loss of harbor cities all over the world. Whether the cause of global warming is human activity and “greenhouse emissions,” a result of naturally occurring cycles, or a combination of the two, this does not alter the fact that it is having swift and tremendous impacts on civilization."