The number of fiscal expirations slated for 2013 will create a $600 billion hole that plunges the nation into “a nasty recession,” says New York University economist Nouriel Roubini.

At the end of this year, tax cuts are set to expire while automatic spending cuts kick in, a combination dubbed by Wall Street as a "fiscal cliff" that could siphon hundreds of billions out of the economy and offset any growth the economy may post.

Failure to act will throw the country right back into recession, Roubini warns.

Editor's Note: Sept. 18 Cover-Up Is a Final Turning for America

"The point is, all this is expiring at year end, and the hole will be $600 billion, or about 4 percent of GDP, and then we plunge into a nasty recession," Roubini says tells CNBC's Maria Bartiromo's One on One column in USA Today.

"Some items may be continued (if the Republicans and Democrats can agree to extend) but a realistic assessment is a fiscal drag," says Roubini.

Meanwhile, he warns that the U.S. economy is currently growing below what it should be, barely on track to hit 2 percent.

"We have positive economic growth, but it's below trend — barely 2 percent," Roubini says.

While the private sectors and households have paid down debts, the government needs to follow suit.

"Job creation is still anemic. The recovery is still anemic because the painful process of de-leveraging has not even started in the public sector. And next year there will be some fiscal drag because of the fiscal cliff that's coming up."

The Federal Reserve, meanwhile has pointed out that Congress and the White House must act to address the country's fiscal imbalance.

"If agreement is not reached on a plan for the federal budget, a sharp fiscal tightening could occur at the start of 2013," the Federal Reserve says in the minutes from its most recent monetary policy meeting.

"Several participants indicated that uncertainty about the trajectory of future fiscal policy could lead businesses to defer hiring and investment. It was noted that agreement on a longer-term plan to address the country's fiscal challenges would help to alleviate uncertainty and consequent negative effects on consumer and business sentiment."

Editor's Note: Sept. 18 Cover-Up Is a Final Turning for America