Whether you like your bourbon neat, on the rocks or in an old-fashioned, the spirit is seeing a huge resurgence in popularity -- and that could be a problem. The growing trend has led to some fears of a "whiskey crisis" if distillers cannot keep up with the popularity, which could lead to higher prices and fewer bottles on shelves, according to a new report from the Associated Press.

Bourbon production is at its highest since the 1970s, but because the spirit has to age for at least two years in a newly charred oak barrel, there is concern the demand will continue to outpace supply in coming years. Bourbon is made with 51 percent corn and stored at 125 proof. Most bourbon distillers age their spirit for four years, reports AP. As of 2012, bourbon distillers produced just over 1 million barrels of new bourbon, a 120 percent increase since 1999, notes the Kentucky Distillers’ Association. There are 4.9 million barrels of bourbon currently aging in Kentucky, and the spirit has reached a new global audience, accounting for $700 million of the $1.5 billion in U.S. distilled spirits exports in 2012.

"Now, bourbon's become a worldwide drink," said Jimmy Russell, master distiller for Wild Turkey. 

Bourbon distillers are finding it difficult to keep up with demand. Maker's Mark, a brand of Beam Inc., faced severe backlash when it announced it would water down its bourbon, from 90 proof (45 percent alcohol by volume) to 84 proof (42 percent alcohol by volume) in February 2013 to better meet consumer demand. Maker's Mark quickly scrapped the plan, saying in a statement, "You spoke. We listened. And we’re sincerely sorry we let you down."