NEW YORK (CNNMoney.com) -- Before you put much hope in forecasts for a 2008 rebound in the battered housing market, consider this: A year ago at this time many top economists were looking for that recovery to begin in 2007.

Instead, the year saw historic declines in nearly every measure of housing strength and home building, and left a trail of predictions from some of the nation's top economists that look - at best - foolish.

Former Federal Reserve Chairman Alan Greenspan and his successor Ben Bernanke, after reviewing home sales and mortgage rates in fall 2006, were hopeful that the market had bottomed out.

"It may be too soon to say that it's over. It may not be too soon to say that the worst is over," said Greenspan in an October 2006 speech in Richmond, according to press reports.

In a November 2006 speech, Bernanke said he saw some "encouraging" signs in recent housing reports.

"Although residential construction continues to sag, some indications suggest that the rate of home purchase may be stabilizing, perhaps in response to modest declines in mortgage interest rates over the past few months and lower prices in some markets," Bernanke said.

But those signs of life were short-lived.

By Feb. 7, HSBC (HBC) was warning that rising losses on mortgage-backed securities would cause it to take a $10.5 billion charge. The phrase "subprime mortgage" was on its way to becoming the key global business term of 2007. And few would use the word "encouraging" in relation to housing again.

Rising mortgage delinquencies and defaults led to a meltdown in the mortgage market, cutting off credit to many homeowners and potential buyers and sparking record levels of foreclosures. That only added to a record glut of both new and existing homes on the market. Historic declines in both the pace and price of home sales soon followed.

Lisa Panasiti, a spokeswoman for Greenspan, said the former chairman was referring in his 2006 remarks to real estate's drag on gross domestic product, and that housing's hit on GDP has since eased.

Many other economists freely admit their year-ago forecasts missed the mark. And while many of those economists are again hoping the year ahead will bring a modest recovery, they are far from certain.

"A lot can go wrong here," said David Wyss, chief economist at Standard & Poor's.

"I thought we'd have problems, but I thought it'd be a smoother adjustment," Wyss said about the problems that developed in mortgage-backed securities. "The financial side was much worse than I thought it was going to be."

A year ago Wyss was forecasting a 7 percent drop in home prices from peak levels. Instead prices fell nearly 10 percent from the July 2006 record.

"Everyone thought I was nuts. Now it turns out I was an optimist," he said.

Wyss' current forecast is that prices will fall another percent or two, but he added that there's a risk of a worse fall-off. His hopes for the start of a turnaround in housing in late 2008 depend on the broader economy not slipping into a recession and foreign investment in mortgage-backed securities continuing to flow. Both of those are risky assumptions, he concedes.

"As foreigners get scared and stop sending money to us, that could send bond yields and mortgage rates up. That's the biggest worry," said Wyss.

The National Association of Realtors made a forecast a year ago that was far more optimistic than those by Wyss and many other economists. The Realtors expected only a 1 percent drop in the pace of existing home sales, and a 1 percent gain in median prices. Instead, 2007 will likely end with a 12.5 percent plunge in the pace of sales, and nearly a 2 percent drop in prices, the first such decline on record.

The group's current forecast for 2008 calls for a 0.5 percent increase in the pace of sales, and a 0.3 percent rebound in prices. But Lawrence Yun, chief economist for the trade group, said that making forecasts is even tougher this year than it was a year ago.

Yun forecasts essentially flat prices in 2008. Yet, he also believes there's at least a one in four chance that prices will fall more than they did this year, and about the same chance that prices could rebound by 3 percent or more.

"I would not be surprised if home sales improves in 2008," he said. "At the same time I can also foresee a circumstance where buyers continue to pull back, the inventory sitting on the market continues to build and it causes prices to go down further."

Yun hopes that housing may get a lift if proposals are enacted to allow government-sponsored mortgage finance firms Fannie Mae (FNM) and Freddie Mac (FRE, Fortune 500) to back mortgages of more than $417,000 in high-priced markets. He also puts stock in proposed reform of the Federal Housing Administration that would help borrowers get loans.

Yun's biggest fear is that Fannie and Freddie's financial problems will worsen substantially in 2008. While he said he doesn't believe that will happen, a financial crisis at one or both firms could shake the housing market enough to cause a recession.

"As long as global providers of capital feel comfortable with Fannie and Freddie, I don't foresee a major crisis," he said. "But if Fannie or Freddie were to be wobbly, that could send mortgage rates to 7 to 8 percent and really choke off demand."

Robert Shiller, a Yale economist who had argued for years that a bubble was forming in real estate prices, points out that one group was on target about where prices would go - investors in a real estate futures market that he helped set up on the Chicago Mercantile Exchange.

Starting in May 2006, the CME set up futures contracts for 10 metropolitan real estate markets, allowing investors to bet whether prices would go up or down and by how much.

By the end of 2006 those futures were pointing to real estate price declines between 5 percent and 7 percent in those markets, Shiller said. That ended up in line with the 6.7 percent annual decline in the October reading of S&P/Case-Shiller home price index, which was the largest drop recorded in that 20-year-old price measure.

"I'm not normally an advocate of market efficiency, but there's something to be said when you're putting money on the line with your prediction, rather than just talking," he said.

Those futures today are far more bearish about future housing prices than most current economists - foreseeing an additional 4 percent to 14 percent drop in prices over the next year.

"I don't have any reason to doubt those forecasts," said Shiller, who does not make forecasts of his own because of his work on his price index and with the markets.

Other economists who had warned of a housing bubble still saw their late 2006 forecasts underestimate the problems that lay ahead.

"A year ago I thought a drop in prices was inevitable, but I didn't know if it would be a bubble bursting or the air leaking out of the balloon," said Dean Baker, co-director of the Center for Economic and Policy Research. "At this point we're seeing a quick meltdown."

Baker's forecast for the drop in existing home sales to 5.6 million homes was essentially spot on. But he underestimated the drop in new housing starts: He forecast 1.7 million and they are on pace to come in at between 1.3 million to 1.4 million.

The problems in subprime mortgages were foreseeable, Baker said. He added that those problems are likely to spread to prime mortgages given to people with strong credit histories. And that could mean that Freddie Mac and Fannie Mae, which have relatively little exposure to subprime mortgages, could need a bailout despite stock sales that executives say have raised the capital they need to weather the storm.

"People still haven't caught up with the fact that this is a larger issue for the mortgage market as a whole rather than just subprime," said Baker.