Many people fear that the Earth's population is growing at a terrifying clip. By the year 2050 the number of people is expected to increase more than 37 percent, to 9.5 billion. There is concern that mankind will run out of natural resources, jobs, food, housing, social services, infrastructure, even physical space. In 25 countries with more than a million residents, the opposite is true: Their populations are shrinking dramatically—threatening not only economic growth, but national prestige. According to a new forecast by the Population Reference Bureau, a Washington-based research group, some countries will see their numbers drop as much as 25 percent by the year 2050. This can cause problems: Declining population means a smaller workforce and lower tax rolls. In nearly every case youth is the most-depleted age group, depriving countries of future economic benefits. The cause is often brain drain, whereby the most educated or skilled citizens sense limited opportunities at home and choose to emigrate. Certain regions will see the greatest proportional decline. The biggest drops are projected for East Asia and Eastern Europe, where only the Czech Republic failed to make the list in a region stretching from the Baltic to the Balkans and eastward to Georgia.