Did you know that even though you can (and often do) drink Green Tea hot, and even though you can have Black Tea cold (think iced tea), the way in which these teas are served does not affect their temperature?
Black Tea is innately warming. The leaves that make up black tea will warm up the body when drunk and it doesn't matter how the black tea is served. On the other hand, Green Tea leaves are naturally cooling. They cool the body, regardless of their preparation.