  If cosmological constant is positive, a black hole is naturally described by
the Schwarzschild-de Sitter solution with two horizons. We use the global
method to extract the topological information and the selection rule for the
Gibbons-Hawking temperature for the thermal vacua. These are related to the
Euler number of the Euclidean section whose topology is more complicated than
expected. We also point out the failure of the usual local method of conical
singularity approach in dealing with multi-horizon scenarios.
