Without better local management, the world’s most iconic ecosystems are at risk of collapse under climate change, says an international team of researchers in study recently published in Science.

Protecting places of global environmental importance such as the Great Barrier Reef and the Amazon rainforest from climate change will require reducing the other pressures they face, for example overfishing, fertilizer pollution or land clearing.

The team of researchers warns that localised issues, such as declining water quality from nutrient pollution or deforestation, can exacerbate the effects of climatic extremes, such as heat waves and droughts. This reduces the ability of ecosystems to cope with the impacts of climate change.

Carl Folke, centre science director and one of the co-authors, believes managing local ecosystems can help maintain and enhance their resilience in the face of global changes.

Unique World Heritage Sites
The authors examined three UNESCO World Heritage Sites: Spain’s Doñana wetlands, the Amazon rainforest and the Great Barrier Reef. While many ecosystems are crucial to their local people, these ecosystems also have a global importance—hence their designation as World Heritage Sites. For instance, the Amazon rainforest is a globally important climate regulator.

Like coral reefs, rainforests and wetlands around the world, these sites are all under increasing pressure from both climate change and local threats.

For example, rising temperatures and severe dry spells threaten the Amazon rainforest and, in combination with deforestation, could turn the ecosystem into a drier, fire-prone and species-poor woodland. Curtailing deforestation and canopy damage from logging and quickening forest regeneration could protect the forest from fire, maintain regional rainfall and thus prevent a drastic ecosystem transformation.

"A combination of bold policy interventions and voluntary agreements has slowed deforestation in the Brazilian Amazon to one fourth of its historical rate. The stage is now set to build on this success by ramping up efforts to tame logging and inhibit fire," says co-author Daniel Nepstad, executive director of Earth Innovation Institute.

An unfolding disaster
"All three examples play a critical role in maintaining global biodiversity. If these systems collapse, it could mean the irreversible extinction of species," says the study’s lead author Marten Scheffer. He is Chair of the Department of Aquatic Ecology and Water Quality Management at the Netherlands' Wageningen University.

In the Great Barrier Reef the global threats are ocean acidification and coral bleaching, both induced by carbon dioxide emissions. Local threats such as overfishing, nutrient runoff and unprecedented amounts of dredging will reduce the reef’s resilience to acidification and bleaching.

"It’s an unfolding disaster. The reef needs less pollution from agricultural runoff and port dredging, less carbon dioxide emissions from fossil fuels, and less fishing pressure. Ironically, Australia is still planning to develop new coal mines and expand coal ports, despite global efforts to transition quickly towards renewable energy," says co-author Terry Hughes, director of the Australian Research Council Centre of Excellence for Coral Reef Studies.

"As a wealthy country, Australia has the capability and responsibility to improve its management of the reef," adds Hughes.

No excuse - act locally
The authors suggest their evidence places responsibility on governments and society to manage local threats to iconic ecosystems, and such efforts will complement the growing momentum to control global greenhouse gases. Yet, in the three cases they examined, they found local governance trends are worrisome.

According to co-author Scott Barrett, the problem is one of incentives.

"These ecosystems are of value to the whole world, not only to the countries that have jurisdiction over them. It may be necessary for other countries to bring pressure to bear on these ‘host’ countries or to offer them assistance, to ensure that these iconic ecosystems are protected for the benefit of all of humanity," says Barrett, who is a professor at Columbia University’s School of International and Public Affairs.

Above all, the paper raises awareness of the great opportunities for enhanced local action.

"Local management options are well understood and not too expensive. So there is really no excuse for countries to let this slip away, especially when it comes to ecosystems that are of vital importance for maintaining global biodiversity," says Scheffer.