In the aftermath of Hurricane Katrina, desperate citizens of New Orleans seeking water, food and shelter began streaming by the thousands out of the city on foot over the US Route 90 bridge across the Mississippi River and into to the city of Gretna, Louisiana. The city had no electricity, no water, no medical services and little in the way of a functioning government. It had been this way for three days when the refugees began streaming in, and unless conditions improved almost immediately, the people of Gretna were looking at severe privation. So they closed the city. Put a line of armed police across the Interstate Bridge and turned the refugees back. Sorry. Can’t help you.

The story has haunted me for nearly ten years. Not just because it is one of the gnarliest ethical problems I have ever come across. But also because in the aftermath of the crash of the Industrial Age — perhaps well before the crash, during the current preliminary stresses — every one of us is going to face the kind of decision Gretna had to make. We will be asked to give help to distressed neighbors when giving that help will endanger our own survival. How will we answer?

Right now, Greece is trying to answer. With its people struggling to survive under a government that is broke and threatening to fly apart, its shores and islands are besieged by a tidal wave of refugees from North Africa. Italy and Spain are similarly afflicted. In many cases they have to rescue the refugees from disable, swamped and/or capsized boats just to get them to dry land, after which no one has any idea what to do with them, at whose expense.

How long will it be, do we think, before the scant armed forces of these Euro-strapped countries will be used not to rescue, but to form a line, like they did across the Interstate at Gretna? Very sorry. Can’t help you. And before we condemn the very idea as a crime against humanity, is it not incumbent upon us to define a workable alternative?

The problem is spreading like a California wildfire. As The Atlantic reported just yesterday (look at the pictures, you will not forget them) the world may never have seen so many refugees as are in flight right now:

“The United Nations announced last year that forced displacement had topped 50 million globally, and early tracking indicates that number may increase yet again this year. Multiple crises worldwide are driving the record migrations, which include Africans and Middle Easterners entering Europe, Rohingya Muslims fleeing Burma, Central Americans traveling to the U.S., civilians escaping violence in Syria, Yemen, Burundi, Somalia, Iraq, and more—all undertaking risky journeys to find better lives.”

The under-appreciated fact is that most of these movements have as their root cause, climate change: chronic drought leading to hunger and thirst, leading to revolution and civil war and chaos.

All of which, hideous as it is, seems comfortably far away. It is, surely, their end of the boat that is sinking. This is America.

Where the states of California, Nevada and Arizona. among others, are toast in the summer sun, their snow packs long gone, their lakes and streams withering away, their crops crisping in the merciless heat. How long will it be before lines of desperate people begin trudging along Interstate 5 into Oregon (nobody in their right mind is going to trudge south, or straight east). And how long before Oregon says, out of the direst of necessities, “Sorry, can’t help you.”

And how long do we suppose it will be before one day, with the power out and the water off and the phones down and the food running out, our neighbor comes to our gate and says, “I’m hungry and I’m thirsty and I need your help.” Okay, that’s one question and it’s fairly easy to handle. Now the next question: what if, in a line behind him, there are a couple dozen more neighbors?

What do we decide, and how do we make the decision?

By comparison, Sophie’s Choice was pretty straightforward.