The state of Washington just released new population estimates for 2004. The verdict: the state’s population grew by 1.1 percent over the previous year, adding 69,500 new residents. And state forecasters are predicting that, with the economy picking up steam in recent months, next year’s population growth will be even faster.
There are two ways to look at this news. First, in historic terms, it’s not that high a percentage growth rate. Since 1900, Washington state has averaged 2.4 percent annual growth, which was more than twice as fast as last year’s rate. That long-term pace has been torrid enough to double the state’s population every 29 years, on average.
But another way to look at it is this: a 1.1 percent increase, though slower than we’ve experienced in the recent past, is still runaway growth. At that pace, the population of Washington state will double, to 12.3 million, by the time today’s preschoolers reach retirement age. Sustained over the long term, this pace of growth would massively increase the human population of our place—making it virtually unrecognizable within a generation or two.
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The disjunction between our perceptions about the pace of change (fairly slow) and the reality (very rapid) underline a very human failing: we’re just plain bad at understanding exponential growth. Because of this failing, we continually underestimate the power of slow, steady changes: a percent or two a year of anything adds up surprisingly quickly.
When asked what was the most powerful force in the universe, Albert Einstein is rumored to have responded “compound interest.” I’m not sure that the quote is accurate, but the sentiment is certainly appropriate to this case.