Most of the world's best places for coffee will be gone by 2050 - and there's an unexpected culprit

Coffee is in trouble.

According to a new study in the journal Proceedings of the National Academy of Sciences, the world's largest coffee-producing regions could shrink by as much as 88% by 2050 as a result of climate change. The study is the first of its kind to look at how bees - key coffee crop pollinators - will be impacted by a warmer planet.

Bees are the unsung heroes of our global food system, responsible for pollinating as many as two-thirds of the crops we eat. Without them, our farms would falter.

As the planet warms, both bees and coffee crops will respond by moving to more suitable climates when they can. Often, those more suitable areas are uphill, where elevation protects them from excessive heat.

But in countries like Nicaragua, Honduras, and Venezuela, that isn't an option. These regions "are less mountainous, so that coffee and bees have fewer options to move uphill," Taylor Ricketts, the director of the University of Vermont's Gund Institute for Environment and a co-author of the recent study, told Business Insider.

In these areas, coffee crops and bees will suffer as the viable land for growing the valuable crop is diminished by warmer temperatures. Based on their models, the researchers estimate these regions could see a reduction of anywhere from three-quarters to 88% of their total area over the next three decades. That's a roughly 60% greater decline than previously estimated.

This may be because past models failed to account for the importance of bees.

Many of the most valuable crops on Earth - from apples and avocados to onions and grapefruit - rely on bees and other pollinators.

"Pollinating bees are worth real money to the farmer," said Ricketts. "They are an input to the crop, just like water or labor."

Some estimates suggest that coffee crop yields rise by as much as 20% when local bee populations are flourishing. Coffee beans also tend to be more uniform when the crops are well-pollinated.

Still, not all regions will face dire consequences as the planet warms. Countries with sizable mountain ranges, like Mexico, Colombia, Costa Rica, and Guatemala may actually benefit slightly from warmer temperatures.

"In these countries, there are some areas where the situation is predicted to actually improve for both coffee and bees," Ricketts said.

Overall, the harms that will result from climate change still outweigh the benefits, according to the latest study. Even in areas where mountains offer some protection from global warming, the average diversity of bee populations is expected to dip about 15% according to the study, putting future populations at risk.

"In general, there is more bad news than good," said Ricketts.

This has big implications beyond a slightly pricier latte.

"Coffee is grown by roughly 25 million farmers in more than 60 tropical countries worldwide. In all, probably 100 million people are involved in its production, most of them rural and poor," said Ricketts. "Climate change threatens the primary livelihoods of millions of people."