Lately, housing data has seemed to get better and better. But esteemed economist Robert Shiller worries that data may be a bit misleading.

In a live interview on Futures Now, esteemed economist Robert Shiller, co-founder of the Case Shiller Index, expressed concerns about US housing even though new data suggests the recovery is well underway.

"Yes, there have been a lot of ," Shiller conceded in a live interview on CNBC, but it's only been that way for 6 months.

And after doing extensive research on housing booms and busts throughout history, Shiller said 6 months isn't long enough for him to feel confident housing is on solid ground. "We've seen reversals of uptrends like this in the past," he explained. "There are still risks."

In fact, those risks, Shiller said, bear an eerie resemblance to those which Japan confronted – during the so-called lost decade, when Japan's economy all but collapsed.

"Japan is the classic example," he said. "Their housing market peaked in 1991 and for the next 20 years it either went down or, at the very least, it didn't go up."

Schiller worries that jobs or the lack thereof introduces a wild card that could trigger an American lost decade in housing. "Employment has been slow to recover," he said. "This isn't what was predicted."

Historically, high unemployment isn't compatible with gains in housing prices because it creates financial anxiety. In turn, that makes people reluctant to make large purchases – especially a purchase as large as a house

"Real estate still faces risks," Shiller concluded.

That's not to say Shiller thinks the scenario outlined above is a foregone conclusion – he doesn't. He simply thinks it's too soon to say the recovery will be long-lasting.

Shiller's comments come just as the latest economic data showed home construction surged 12.1 percent in December, its fastest pace in over four years.

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