lower risk of heart disease and premature death. but some coffee crops are being threatened now by changes in the environment. mark phillips has tonight's "climate diaries." >> reporter: to many, it's the other dark liquid that powers the world-- coffee. but because of the damage being done to the planet by the primary dark liquid-- oil, along with other fossil fuels-- coffee is in trouble, and so are the farmers who grow it. is this a good harvest year or not so good? >> it is not so good. >> reporter: up here in the mountains of eastern uganda, coffee is the most important thing they grow. anthony and vincent khabala's family have been growing it on their farm, about 4,000 feet up the sloams of mount elgon, for generations. lately, though, they've been having problems they've never had before. it turnlz out, coffee is as fussy as the people who drink it. it likes the right altitude, the right temperature, and the right