For months you’ve heard warnings about the Very Bad Things that could happen if Congress fails to raise the debt ceiling. U.S. government default! Market crash! Global financial crisis!

That probably feels abstract, maybe even hyperbolic. Worldwide financial meltdown? Really?

I spent recent days talking to financial market experts and former government officials about the potential fallout. I wanted to better understand the channels through which panic and losses could spread and precipitate “financial Armageddon,” as one former Federal Reserve official dubbed it. (Other phrases that came up in interviews: “nightmare scenario,” “bankruptcies that rival those in the Great Depression,” and “we might have to go back to trading beads.”)

...One useful lens for thinking through possible consequences was suggested by Richard Berner, a senior Treasury official during the 2011 debt-limit crisis: The global financial system is like an upside-down pyramid, and the tip of that pyramid is the U.S. Treasury market. “Everything else rests upon it,” he told me.

With these disclaimers, here’s a summary of what market experts relayed. Our scenario assumes the U.S. government fails to pay for not only key services such as Social Security checks and military salaries but also principal or interest on at least some U.S. Treasury securities. (It’s unclear whether the government has technical capacity to effectively prioritize payments, anyway, or if ratings agencies would care.) On to the consequences, in seven terrifying steps: [I'm just sharing the terrifying headlines; read the opinion piece for a discussion of each.]

1) Treasurys get downgraded — as does virtually every other asset on earth.
2) Interest rates rise for U.S. consumers, businesses and the government.
3) The dollar might lose value in foreign-exchange markets.
4) Stock markets plummet.
5) Companies holding Treasurys suffer hits to both revenue and balance sheets.
6) There might be a scramble to close out trades that people would otherwise hold.
7) Some of the infrastructure underpinning large parts of the financial system (called “central counterparty clearinghouses”) could essentially get overwhelmed and go down.