This was the question posed by meteorologist, Edward Lorenz, in a 1972 talk he gave to the 139th meeting of the American Association for the Advancement of Science. Lorenz began his research into weather patterns in the early 1960s and was one of the 'inventors' of Chaos Theory and is sometimes referred to as the 'father' of Chaos Theory. Lorenz's talk is in his book, The Essence of Chaos. Lorenz's 'Butterfly Effect' and the term 'Butterfly Effect' was later mentioned and popularized in Gleick's book, Chaos: Making of a New Science where he depicts graphs identifying Lorenz's 'Strange Attractor', a collection of states, which resembled a butterfly's wing, as well as a describing Lorenz's findings in his book.

Climate change cultists beware, Lorenz's research led him to the conclusion that long term weather patterns can't be predicted, and that the periodic ice ages (climate change) the earth goes through may simply be a product of Chaos rather than controlled by external factors.

Chaos theory:

chaos theory, in mechanics and mathematics, the study of apparently random or unpredictable behavior in systems governed by deterministic laws. A more accurate term, deterministic chaos, suggests a paradox because it connects two notions that are familiar and commonly regarded as incompatible.

Don't worry my head hurts too…Finding patterns and predictability in the unpredictable. Seems like a fun job…