Starbucks customers across hundreds of locations in the United States started their weeks off with a surprise: Their beloved Frappuccinos and iced espresso drinks served in paper cups, not plastic.

Starbucks will replace its plastic cups at select stores in California and several other states after a KCAL News investigation showed that its current plastic cold cups ended up in landfills.

They are not being rolled out nationwide, Starbucks confirmed to the publication. The compostable cups are made from fiber-based paperboard with a bioplastic liner, making the cold beverage cups ...