The ongoing global economic recession is the prime external economic driver for Starbucks. As I already mentioned, this factor dented the profitability of Starbucks. This has convinced buyers to shift to cheaper alternatives. As they did not quit buying coffee, Starbucks should seek an opportunity here.
The company has to deal with rising labor and operational costs. The inflationary environment and falling profitability is causing a lot of stress.
Some other economic factors which can affect Starbucks are:
Local currency exchange rates
Local economic environment in different markets
Taxation level