Explosive global population growth in the Cold War era made concern over low birthrates passe. “Sub-replacement fertility” is a technical term that means a total fertility rate of less than about 2.1 children per woman, the number needed for each generation to exactly “replace” itself numerically. It’s convenient to summarize fertility in a single number, but the total fertility rate is a complicated metric. Essentially, low fertility and population decline lead to an aging population and a larger share of old people relative to working-age people. The larger key to transforming the way we talk about population is accepting that no trend, past or future, lasts forever.

Source: Washington Post March 18, 2019 21:00 UTC