Morgan Stanley's Steven Roach says a double dip recession is now 40 percent certain.

"There are many stiff headwinds that are going to restrain the global expansion over the next few years," he says.

"I think global growth is going to be anemic and I'd put a 40 percent chance on a double dip at some point in the next couple of years," Roach told CNBC.

Roach also says it's pretty unfair of politicians to put so much blame on banks alone for the financial crisis, and forget the roles played by ratings agencies and government itself.

"The banks didn't do it alone (the crisis) ... there was a shared responsibility... yes, even from the brilliant political overseers, who now feel they have the keys to the postcrisis kingdom."

“I think that all any of us would ask as we debate the postcrisis architecture is that we recognize that the banks didn’t do it alone,” Roach said in reference to the economic summit at Davos, Switzerland.

“Shared responsibility has got to be the key here.”

Lynn Reaser, chief economist for the National Association for Business Economics, sees the likelihood of a double dip as less than 50 percent, The Canadian Press reports.

"It will become more acute if there are delays in confirming a successor," Reaser says, noting that the economic recovery remains fragile, with spending still weak, credit tight and job creation scarce.