Timing is everything, even in apocalyptic doom-mongering. When my book America Alone came out in 2006, the conventional wisdom was that its argument about Europe's demographic death spiral was "alarmist" (The Economist). Seven years on, it's so non-alarmist that even the Washington Post is running stories about the Continent's "plummeting" birth rates. The Post's focus was on a small corner of the Portuguese interior, wherein their reporter met Maria Jesus Rodrigues, 87, who recently moved into the old folks' home from her nearby village. The youngest resident is 57. Not in the old folks' home, but in the village. That's to say, the entire parish qualifies for membership in the AARP, which regards you as a potentially "retired person" from the age of 50.

"Retirement" is an invention of the 20th century, and will not long outlive it. When everyone's a senior, nobody is — because, if there are no young people around to pave the roads, police the streets, weed your garden, fix your roof, give you a bed bath, and change your feeding tube, you're going to have to do it yourself. In The Children of Men, P. D. James's dystopian novel of a world turned mysteriously barren, the roads are potholed and broken, and the buildings crumbling, for want of a sufficiently able-bodied population to maintain them. By 2021, the year Lady James's story is set in, much of inland Portugal will be approaching the same condition — not through biological affliction, but through a kind of silent mass consensus that this is no longer a world worth bringing children into.

"A country without children is a nation without a future," warned Aníbal Cavaco Silva, Portugal's president, in 2007, since when the fertility rate has nosedived. Why would you have a kid in Portugal? The country's youth-unemployment rate is over 40 percent. In Spain it's 57 percent, and in Greece just shy of 63 percent.

I don't know the rest of the country terribly well, but I love Lisbon, and I love returning there. There is something about the jacarandas in bloom that always reminds me of a brief youthful fling long ago. Because I was young, and she was young and lovely, I find it sad to think of Portugal as a geriatric ward with insufficient "carers" to change the bedpans. Today, Lisbon remains an architecturally splendid city — a beautiful museum, as one Commonwealth foreign minister described it to me after a flying visit. But the buildings are defaced from top to toe with graffiti, which the stylish Portuguese ladies bustling through the upmarket boutiques no longer even notice. Even as a beautiful museum, Lisbon is already decaying. "The writing on the wall" is from Belshazzar's feast, but who knows his Bible in post-Christian Europe? So, even when the writing is all over every wall, nobody sees it.

Once upon a time, Portugal was an empire that reached as far as Brazil. Now the empire is a backwater, and soon it will be a graveyard, and then an untended graveyard. I wrote in these pages four years ago that this was the first demographic recession, a valse macabre between economic sclerosis and population decline. Eurostat, the European Commission's official statistics agency, is now singing the same mournful dirge: In May, they released a report titled "Towards a 'Baby Recession' in Europe?" By 2011, the fertility rate had fallen in two dozen countries, and in none is it at replacement rate.

The Eurostat report makes much of the difference between fertility rates varying from 2.05 in Ireland to 1.2 in Romania. But the easiest way to get the picture is to take a map of the Continent and draw a diagonal line from northeast to southwest. In northern and western Europe, obstetrics is still just about a viable profession; in eastern and southern Europe, the maternity wards are out of business. One can speculate about the reasons for this difference: The Left argues that it's because of a more generous social safety net in the northwest than in the Mediterranean states and the recovering Soviet satellites. On the other hand, it's obvious that Denmark, Belgium, France, and Britain's healthier fertility rates owe something to the fecund Muslim populations they've attracted. A united Germany has a foot in both camps, being both prosperous with generous maternity benefits and a large Muslim population, and well down the demographic death spiral.

Setting Islam to one side, there is a horrible enfeebling fatalism on both sides of that demographic line. As I wrote in my "alarmist" book seven years ago, the future belongs to those who show up for it, and the nations that built the modern world — which is to say the last half-millennium of human history — have collectively checked in to one of those Swiss euthanasia clinics. In 1905, Theodore Roosevelt spoke to the National Congress of Mothers about the citizen who consciously forgoes "the blessings of children": "Why," he declared, "such a creature merits contempt as hearty as any visited upon the soldier who runs away in battle, or upon the man who refuses to work for the support of those dependent upon him, and who though able-bodied is yet content to eat in idleness the bread which others provide."

Today, millions of able-bodied citizens are content to eat in idleness the bread provided by others, and it is a long time since Europeans were called on to fight any battle. But a society that has nothing to die for has nothing to live for. Only the Portuguese can change the destination they're headed to: have a kid, have two or three, and vote for the possibility of a future.