Hello and welcome to the Intelligence, from the Economist. I'm Jason Palmer.

And I'm Aurea Gumbhi. Every weekday, we provide a fresh perspective on the events shaping your world.

The Atlantic Meridional Over-Turning Circulation is the most important ocean current that almost no one has heard of.

If it were to stop disastrous effects would follow on both sides of the Atlantic. And bad news, it looks as if that day might be coming.

And there's a certain amount of etiquette that every airline passenger should follow. Not that you'd know it sometimes.

But for business travellers, the suggested decorum is a little more restrictive still. After all, you might find the boss three rows back.

First up there.

So I was recently in Hazard, which is town in eastern Kentucky in the Appalachian Mountains.

Daniel Knowles is the economist's American Midwest correspondent.

The place that used to be home to a lot of America's coal industry, in fact there's still some there.

But it's also a place where the opiate crisis has been in trench for a very long time.

A man urges back. If he is not back to work, they will replace him. And I cannot have supported my family on the disability.

20, 30 years ago in doctors were really prescribing the opiates to coal miners to manage chronic pain from working down a mine.

Since I've been on this new paying medication, I have not missed one day of work.

Now I can enjoy every day that I live.

I have found life again and I'm so grateful.

Now it's become a lot worse.

For many years, the annual number of Kentuckyians that die from drug overdoses have steadily climbed.

Opioids are now the biggest drug epidemic in American history.

I walked into a place that called the Rebound Recovery Centre, which is a drug's treatment clinic,

and they have this whiteboard on the wall.

The population of Hazard is only about 5,000, but on the whiteboard they list everybody who's died,

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