AIROBI, Kenya (AP) -- From ancient ruins in Thailand to a 12th-century settlement off Africa's eastern coast, prized sites around the world have withstood centuries of wars, looting and natural disasters. But experts say they might not survive a more recent menace: a swiftly warming planet.

"Our world is changing, there is no going back," Tom Downing of the Stockholm Environment Institute said Tuesday at the U.N. climate conference, where he released a report on threats to archaeological sites, coastal areas and other treasures.

Recent floods attributed to climate change have damaged the 600-year-old ruins of Sukhothai in northern Thailand, the report said, while increasing temperatures are "bleaching" the Belize barrier reef and a rising sea level is sending damaging salt into the wetlands of Donana National Park in Spain.