Climate change is threatening to destroy three of the world’s most important UNESCO World Heritage sites if local officials don’t step up their preservation efforts, according to an international team of researchers.

A study published in the Science journal last month found that South America’s Amazon rainforest, Australia’s Great Barrier Reef and Spain’s Donana wetlands are all at a risk of collapse without better local management.

All three ecosystems are designated UNESCO World Heritage sites because of their global importance. The researchers say local authorities must do more to prevent overfishing, pollution and land clearing, among other human activities that make them more susceptible to the effects of climate change.

"Poor local management makes an ecosystem less tolerant to climate change and erodes its capacity to keep functioning effectively," the study’s lead author, Marten Scheffer of Wageningen University in the Netherlands, said in a statement.

Although great strides have been made to reduce deforestation in the Brazilian Amazon, more needs to be done to protect the rainforest from clearcutting and rising temperatures, which could lead to devastating fires, researchers say.

Ocean acidification and coral bleaching, both blamed on carbon dioxide emissions, could spell disaster for the Great Barrier Reef. Overfishing, dredging and coastal developments are only making matters worse, the researchers say. The Australian government has been accused of not doing enough to protect the reef, despite a recent ban on dredge waste dumping. 

UNESCO has been debating whether to place the Great Barrier Reef on its list of World Heritage sites in danger, but a decision isn’t expected until June.

The Donana wetlands in southern Spain, meanwhile, have been degraded by agricultural runoff and urban waste water. The wetlands host more than half a million birds in the winter months, but the water has been tainted with toxic algal blooms.

Researchers say climate change could lead to more severe blooms, dangerous to plants and animals. They say local officials must do more to reduce fertilizer use and water pollution in the region.