Finance: Warnings about America's impending financial car wreck are being sounded, loud and clear. The only question is whether those driving the car will slam on the brakes before it's too late.

No doubt alarmed at the headlong plunge into fiscal irresponsibility by both the White House and the Democrat-dominated Congress, Wall Street is starting to fret that the recklessness could touch off another financial crisis.

On Thursday, Standard & Poor's said action is needed soon if the U.S. is to keep the much-coveted AAA bond rating that lets the government borrow in global markets at the lowest rates possible.

S&P's warning came just days after Morgan Stanley asserted that the U.S., along with a number of other developed nations, is likely to default on some debt. Such defaults are "inevitable," it said, given the growing number of retirees in developed nations who will have to be taken care of by a shrinking pool of workers.

The sovereign debt crisis "is not over," said the investment bank's Arnaud Mares, and that includes in the U.S.

What worries Wall Street is a public debt-to-GDP ratio of around 53%. That's high enough as it is, but it's about to go a lot higher. By 2020, recent data suggest, the ratio will top 100% — a red line that virtually all economists agree is dangerous.

In raw numbers, we owed roughly $7.5 trillion at the start of this year. By 2020 that explodes to $23.5 trillion, according to an analysis of Congressional Budget Office data by economist Brian Riedl.

What do these numbers mean? To begin with, we spend $187 billion a year, or 1.3% of GDP, to pay our debts now. Just 10 years from now, that will surge to $1.1 trillion, or 4.8% of estimated GDP. Fiscally speaking, we'll be gasping for air.

Debt can be a good thing, but in big doses it's poison. If, as some fear, the U.S. should simply say it can't pay its debts and default — or do a de facto default by printing money to retire our debt — the consequences would be dire.

No nation would want our bonds in their portfolios. To entice them to buy, we'd have to offer a much higher risk premium — that is, higher interest rates.

That means our debt service could go even higher, squeezing out even more of our economy's spending.

The dollar would implode, and prices for foreign goods — which now make up 15% of our economy — would soar. Private investment would shrink and, along with it, private-sector GDP

Americans' standard of living, once the envy of the world, would recede into the pack of mediocre, government-run nations.

It doesn't have to be this way. All this is due to unrestrained spending. The federal government now spends about $29,000 per household. That will rise to $38,000 by 2020. If you think "the rich" will, or can, pay for it all, think again.

Unless we begin to control spending, we can kiss our American lifestyles goodbye. It's that simple.

Sadly, the White House is unwilling to see reality. Which may explain why, as our debts mount to ruinous heights, Vice President Joe Biden — President Obama's point man on the recovery — can burble, "This is a chance to do something big, man!"

Yeah, man, something big — like wreck a country.