TIMBIO, Colombia - In the last few years, coffee yields have plummeted here and in many of Latin America's other premier coffee regions. Rising temperatures and more intense and unpredictable rains are to blame, phenomena that many scientists link partly to global warming.

Yet as stockpiles of some of the best coffee beans shrink, global demand is soaring as the rising middle classes of emerging economies like Brazil, India and China develop the coffee habit. Coffee plants require the right mix of temperature, rainfall and spells of dryness for beans to ripen properly and maintain their taste. Coffee pests thrive in the warmer, wetter weather.

Most of the small landowners in Colombia's lush mountainous Cauca region have thrived for decades by supplying shade-grown, rainforest-friendly Arabica coffee for top brands like Nespresso and Green Mountain. The shortage of the Arabica beans is being felt in New York and Paris, as customers blink at escalating prices. Purveyors fear that Colombia's Arabica supply may not rebound.