Starbucks Corp said on Monday it will begin phasing out use of plastic straws at its restaurants by 2020, giving environmentalists a sizeable victory in their campaign to convince restaurants to abandon plastic utensils.

The Seattle-based chain said it would eliminate single-use plastic straws globally at its 28,000 locations. The straws will be replaced by new recyclable strawless lids and alternative material straws.

Its announcement came just days after its hometown of Seattle barred plastic straws and utensils at restaurants, amid a broader global push to discourage the use of plastic straws and other one-time use plastics

"For our partners and customers, this is a significant milestone to achieve our global aspiration of sustainable coffee, served to our customers in more sustainable ways," Starbucks Chief Executive Kevin Johnson said in a statement.

Last month, rival McDonald's Corp, the world's largest restaurant chain, announced plans to transition to paper straws at its UK and Ireland restaurants, beginning in September with completion in 2019.

The McDonald's decision does not extend to its other global restaurants, however. A proposal to investigate the impact of plastic straws at its 37,000 worldwide restaurants, what would have been a step towards phasing out plastic straws, was shot down by shareholders in May.

The UN Environment Programme estimates that some 8 million tons of plastic is dumped into the ocean every year - the equivalent of dumping a garbage truck full of plastic every minute - killing birds and marine life and compromising the ocean ecosystem.

Plastic straws represent a comparatively small amount of all plastic waste. However, they are more difficult to recycle than other plastic items.

Dylan de Thomas, vice president of industry collaboration at The Recycling Partnership, said that curbside recycling programs in the United States don't typically accept straws. Even for those consumers who recycle plastic items, a straw is so small it can be difficult to sort.

"It's really thin. It's really small. It's really light. So it's really challenging in our existing sortation system to be able to sort it out," he said.

In contrast, paper straws are often compostable. When disposed of in a landfill, paper straws decompose at a much faster rate than plastic ones.

For businesses, paper straws are also more expensive than their plastic counterparts. Per 250 straws at UK-based catering equipment company Drinkstuff, paper straws cost about $8.62 (£6.49), versus $1.66 (£1.25) for plastic, for instance.

In 2017 there were about 63 billion straws used in the United States per year, around 170-175 million straws per day, according to data provided by Technomic.

"Taken in isolation I don't know that anyone would argue that slightly higher straw costs are going to break the backs" of restaurant owners, said David Henkes, senior principal at Technomic food service consulting company.

"But you couple it with rising costs in a whole lot of other categories and that's where the challenge comes... It's a small increase here, and a small increase there."

Grassroots conservation groups have been among the most vocal opponents of plastic straws, though the push to paper and other biodegradable and recyclable materials has found support in some corporate boardrooms as well.

Earlier this year, the fifth-largest US carrier, Seattle-based Alaska Airlines, said it would be going strawless, beginning this month.

"There's always going to be people who still buy plastic straws," Drinkstuff head of marketing Buzz Seager said in a phone interview. "Especially if you're a little venue, prices are always going to be a bit of a barrier to it."

Yet Seager said the company has seen an increase in demand from customers for straws that are better for the environment.

"You basically just pay for the privilege of being eco-friendly," Seager said.