The good news is that besides Arabica, there's another variety of coffee that is much easier to grow. The bad news? Most coffee lovers agree that it tastes terrible.
Essentially all of the world's coffee comes from one of two species: Arabica and Robusta. There are others, but they don't make a dent in worldwide consumption numbers. When Americans think of coffee, they think of Arabica—it's what's used in most drip coffee makers, espresso machines and sold in specialty coffee shops. It tastes smooth and bold.
It also requires "Goldilocks" conditions in order to grow, says Mauricio Galindo, head of operations at the London-based International Coffee Organization, a group that tracks the global coffee market and threats to coffee production.
"Arabicas are the ones at risk—they're very delicate trees," he says. "They depend on conditions that are not too warm, not too cold, not too wet, not too dry."
Besides needing near-perfect conditions to grow, Arabica is also highly vulnerable to a fungus known as coffee leaf rust, a disease that originated in Africa and Asia but has since spread to every coffee-growing region except for Hawaii and Australia. As its name implies, the fungus turns a coffee plant's leaves a dark brown, causing leaves to eventually fall off. An infected tree will have a lower coffee yield and may eventually die.
Left unchecked, coffee rust has the potential to completely destroy a country's crop. In the mid 1860s, the disease essentially wiped out all of Sri Lanka's coffee plantations. More than 100 years later, Sri Lanka still doesn't have any significant coffee production, according to the International Coffee Organization.
For decades, coffee farmers in South and Central America were insulated from the disease's effects because coffee plants in the Americas are grown in the cool mountains, where temperatures weren't warm enough to be suitable for the plant. But in the 1970s, the first cases of coffee rust reached Brazil, and increasing temperatures and rainfall caused by climate change have allowed the fungus to live at higher altitudes.
According to Galindo, "everything points to climate change being the main factor influencing this explosion in coffee leaf rust."
In February, Guatemalan President Otto Perez Molina declared a state of emergency in the country after an estimated 70 percent of its coffee plants had been infected with the disease. The country's estimated 2013-2014 coffee haul could be reduced by more than 40 percent, and the fungus has caused similar problems for Guatemala's neighbors.
Corrected 03/28/13: An earlier version of this story misstated the total value of the worldwide coffee trade.