Japanese workers will again ditch their neckties and dress casually this summer to combat global warming in an iconic seasonal campaign known as Cool Biz.

Starting June 1, thermostats in public buildings will be set at 28 degrees to cut back on air conditioning and carbon dioxide emissions from power plants, the government announced Friday.

To endure the balmy offices, Japanese workers — traditionally clad in suits and ties — are urged to don Cool Biz attire and dress lightly in open-collar short-sleeve shirts.

"We hope the public will reconsider their individual lifestyles and cooperate where they can to protect the environment," Chief Cabinet Secretary Yasuhisa Shiozaki said.

Prime Minister Shinzo Abe has urged all of his Cabinet ministers to wear Okinawan shirts — a Japanese version of the Aloha shirt — on June 1 to mark the start of the campaign, which will run through the end of September.

The energy conservation campaign was introduced in summer 2005 to help Japan meet its obligations under the Kyoto Protocol on global warming, and has been going strong since.

"Even small efforts by each member of the public will produce a big result if all of us work together," Shiozaki quoted Abe as saying.

Figures show the Cool Biz campaign in 2006 cut carbon dioxide emissions by 1.14 million tons.