Across the globe, in the United States and Uruguay, in Italy and India, families are getting smaller. To some, this may seem like good news. In an era of human-induced climate change, it’s hard for many liberal, environmentally minded people to rally around having more children — harder still for many young Americans of all political stripes to imagine raising and supporting three children when rent can eat nearly a third of their paycheck.

But economists, demographers and government leaders are increasingly alarmed about the downward trend. According to the latest United Nations projections, the world’s population will peak in 60 years. After that, experts say, humanity will face an unprecedented decline — and, along with it, profound social and geopolitical consequences.

The average fertility rate in the United States has not been above the 2.1 replacement rate since 2007, according to World Bank data. Currently, no country in the developed world, barring Israel, has a fertility rate above replacement level, and, based on U.N. projections, by the end of the century, almost every country will have a shrinking population.

A McKinsey report exploring falling fertility rates says that the trend is “propelling major economies toward population collapse in this century,” pushing society into “uncharted waters.” Think empty schools and crowded retirement homes; dwindling Social Security; and a voting public that skews far older than generations past. Further down the line, shrinking populations could spur mass migration and new global conflict. – Washington Post