The global financial crisis has cast the world's economic system into panic. In response to this unprecedented fiscal emergency, governments are rushing to support collapsing banks, ruined financial institutions, devastated investor confidence and the consequent worldwide liquidity crash – when money is no longer available to borrow and invest, the economic system can no longer function.

The primary cause of this financial crisis is the free-market capitalist system practiced and exported globally by the United States. This essentially American economic ideology – practiced with particular enthusiasm during the last eight years – has been intent on reducing government control by deregulating everything financial. And the country's solution to its every fiscal problem has been to stimulate economic growth by lowering interest rates and increasing borrowing.

The consequences have led to dollar figures that are truly staggering. Between 1990 and 2000, US national debt rose from $3 trillion to $5.75 trillion. On September 23, 2008, it was $9,536,317,678,235 – $9.5 trillion. It is now approaching $11 trillion. In addition, American credit card debt on that Tuesday in September, was $2.5 trillion or, more precisely, $2,587,427,300,000. Total American personal debt has risen from $680 billion in 1974 to $14 trillion today (Fareed Zakaria, Newsweek, Oct. 20/08).

The subprime fiasco ended the illusion that constant borrowing and overspending could proceed indefinitely. Overextended American consumers discovered they could no longer support the heavy burden of debt caused by using extremely low interest rates to mortgage houses for either purchase or as collateral for other purchases. Foreclosures began and house values began to fall. Then the lost collateral could no longer guarantee the debt.

Unfortunately for the financial system, about $3.2 trillion of this unsecured debt was hidden in other investment packages and distributed into the global financial system. As the housing market in the US began to collapse, no one knew where the bad debt was. Banks and investment houses around the world could neither lend nor borrow because they couldn't verify the status of their money. So the whole financial system, built on trust and confidence, began to collapse.

To halt this collapse, the US government began to assume responsibility for the bad debt of its banks, investment businesses and mortgage institutions by issuing treasury bills: $200 billion for the mortgage giants Fannie Mae and Freddie Mac, billions more for other businesses facing ruin, and then $700 billion "to purge the financial system of bad debt" (Globe & Mail, Oct.4/08).

But the global financial system spread the contagion internationally. South Korea, for example, has had to support its financial system with the equivalent of $130 billion in guarantees, France $468 billion and Britain $660 billion. In total, world governments have committed over $3 trillion to ease the financial crisis. And the amounts will likely rise as the full impact begins to undermine economies. Iceland is on the verge of national bankruptcy.

This global financial story, ominous as it is, has an even more ominous parallel in the planet's environmental condition. Just as the free-market financial system has risked collapse by borrowing beyond its means, so are we using Earth's resources beyond replacement capacity. The New Economics Foundation, an international think tank on environmental issues, calculates that from October 6 until December 31 we will be in "ecological overdraft" – "the point at which human consumption exceeds the ability of the Earth to sustain it in any year and goes into the red" (The Vancouver Sun, Oct. 6/08). For those 86 days, we will be living on resources borrowed from the future.

"Ecological Debt Day this year," the NEF reports, "is three days earlier than in 2006, which itself was three days earlier than 2005" – a date that has "moved steadily backwards since humanity began living beyond its environmental means in the 1980s" (Ibid.). We can understand this more clearly by saying that we are using more vegetation than ecosystems can regrow, catching more fish than oceans can replace, emitting more carbon dioxide than air can recycle, extracting more nutrients than soils can replenish, discharging more pollutants than biosystems can neutralize.

Indeed, if the United States were successful in exporting its brand of free-market economics and consumption to everyone in the world, we would need 5.3 Earths to live sustainably. Coincidentally, our human "ecological overdraft" is nearly 24% (86 of 365 days), which is almost exactly the debt-to-income ratio of American consumers.

But the parallel between economics and environment ends with these numbers because issuing more treasury bills, as the US Federal Reserve has done, will not grow more vegetation, replenish exhausted soils or replace depleted fish stocks. While Americans and the world's financial experts are confident that the free-market economic system is resilient enough to eventually rebound, we have no such assurance that collapsing ecosystems can recover with the same resilience. Indeed, almost every indication is that our present relationship with the planet's ecosystems is moving toward an end-game – "One Earth, One Chance".

Clearly, our global economic system needs some important refinements if we are to avoid another financial crisis. But the free-market capitalism which is threatening our monetary system is also taxing Earth's ecologies beyond sustainability. If the prospective changes to our economic system are to make human commerce more stable and reliable, then the changes must also end our habit of living in "ecological overdraft". Any economic system that fails to recognize environmental limits will ultimately fail – catastrophically.