Average temperatures in Colombia’s coffee regions have risen nearly one degree in 30 years, and in some mountain areas the increase has been double that, says Cenicafé, the national coffee research center. Rain in this area was more than 25 percent above average in the last few years.

At the new, higher temperatures, the plants’ buds abort or their fruit ripens too quickly for optimum quality. Heat also brings pests like coffee rust, a devastating fungus that could not survive the previously cool mountain weather. The heavy rains damage the fragile Arabica blossoms, and the two-week dry spells that prompt the plant to flower and produce beans occur less often, farmers say. Arabica beans take about seven months to mature.

“Half a degree can make a big difference for coffee  it is adapted to a very specific zone,” said Néstor Riaño, a specialist in agroclimatology for Cenicafé. “If temperature rises even a bit, the growth is affected, and the plagues and diseases rise.”

While climate scientists agree that the increase in temperature is a clear signal of global warming and high ocean temperatures are generally associated with more frequent storms, scientists are uncertain whether the peculiar weather patterns in the area are directly related to warming, said Stephen E. Zebiak, director general of the International Research Institute for Climate and Society at Columbia University.

“It is hard to know whether this severe weather represents natural fluctuations or is a climate change signal, though from a risk management sense, there is good reason to consider how to cope with these extreme events,” Dr. Zebiak said.

In the hope of restoring coffee output, researchers at Cenicafé’s labs are toiling on a mission that seems as pressing a priority for Colombia as curing cancer is for medical researchers.