We live in scary times, Paul Krugman writes in his Friday New York Times column. So scary that they put the esteemed economist in mind of 1930s Europe.

The rising inequality problem, well established by Thomas Piketty’s “Capital in the 21st Century,” has concentrated so much wealth in the hands of so few, while millions of others live in what Krugman poetically calls the "Valley of the despond."

The only other group that is doing well, besides the global elite, says Krugman, is "what we might call the global middle — largely consisting of the rising middle classes of China and India." For a crystal clear view if what is going on he suggests consulting a remarkable chart of income gains around the world produced by Branko Milanovic of the City University of New York Graduate Center.

Of course, there is a huge plus side to rising incomes for those living in those developing nations where hundreds of millions of people have been lifted out of terrible poverty. But in advanced countries, there are also worrisome signs on the horizon:

Between these twin peaks — the ever-richer global elite and the rising Chinese middle class — lies what we might call the valley of despond: Incomes have grown slowly, if at all, for people around the 20th percentile of the world income distribution. Who are these people? Basically, the advanced-country working classes. And although Mr. Milanovic’s data only go up through 2008, we can be sure that this group has done even worse since then, wracked by the effects of high unemployment, stagnating wages, and austerity policies. Furthermore, the travails of workers in rich countries are, in important ways, the flip side of the gains above and below them. Competition from emerging-economy exports has surely been a factor depressing wages in wealthier nations, although probably not the dominant force. More important, soaring incomes at the top were achieved, in large part, by squeezing those below: by cutting wages, slashing benefits, crushing unions, and diverting a rising share of national resources to financial wheeling and dealing.

Worse still is the fact that no one is really speaking up for those who are left behind. Conventional parties of the so-called left are barely audible in France, Britain and the U.S. Leaders like Obama are too afraid to "challenge elite priorities, in particular the obsession with budget deficits, for fear of being considered irresponsible," Krugman writes. "And that leaves the field open for unconventional leaders — some of them seriously scary — who are willing to address the anger and despair of ordinary citizens."

Here is where Krugman sounds the alarm about the rise of some parties in Europe that bear an unpleasant resemblance to something the world has seen and suffered through before. The circumstances are ripe: this is the second time the world has experienced a global financial crisis, immediately followed by a protracted worldwide slump. If you guessed that the first time was 1930s Europe, then you might already be worrying right along with Krugman.

In Greece, it is less-scary leftists who are on the rise. "Elsewhere, however, we see the rise of nationalist, anti-immigrant parties like France’s National Front and the U.K. Independence Party, or UKIP, in Britain — and there are even worse people waiting in the wings," Krugman writes, concluding that if our leaders don't face up to reality, the world could get very ugly, again.