Important global ecosystems like the Amazon rainforest and Great Barrier Reef are in danger of breaking down because of a combination of local pressures and climate change, but better local management could help make these areas more resilient, say the authors of a paper published by Science this week.
Ecosystems may show only a slight response to changing climate until they hit a tipping point, when even small changes could bring about a collapse. The paper’s authors contend that improving local conditions could forestall the impacts of climate change, perhaps more effectively than global efforts to curb the greenhouse gas emissions driving the warming.
While local governments have made some progress in protecting important ecosystems, the areas are still under increasing threats from development, land-clearing, overfishing and fertilizer pollution. The authors say that local stewardship of the areas “is at risk of failing.”
“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,” said Barrett, who is also a professor at Columbia University’s School of International and Public Affairs.
The authors examined three UNESCO World Heritage Sites: Spain’s Doñana wetlands, the Amazon rainforest and the Great Barrier Reef. While many ecosystems are important to their local people, these ecosystems have a global importance—hence their designation as World Heritage Sites. For instance, the Amazon rainforest is a globally important climate regulator.
The international team of researchers warns that localized 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.
“We show that managing local pressures can expand the ‘safe operating space’ for these ecosystems. Poor local management makes an ecosystem less tolerant to climate change and erodes its capacity to keep functioning effectively,” says the study’s lead author Marten Scheffer, chair of the Department of Aquatic Ecology and Water Quality Management at the Netherlands’ Wageningen University.
“All three examples play a critical role in maintaining global biodiversity. If these systems collapse, it could mean the irreversible extinction of species,” Scheffer said. “Local management options are well understood and not too expensive. So there is really no excuse for countries to let this slip away.”
The Doñana wetlands in southern Spain are Europe’s most important wintering site for waterfowl, hosting over half a million birds, and home to numerous unique invertebrate and plant species. Nutrient runoff from the use of agricultural fertilizers and urban wastewater is degrading water quality in the wetlands, causing toxic algal blooms, which endanger the ecosystem’s biodiversity. A warming climate could encourage more severe blooms, causing losses of native plants and animals, say the researchers.
“Local managers could lessen this risk and therefore boost the wetlands’ climate resilience by reducing nutrient runoff,” says co-author Andy Green, a professor at the Doñana Biological Station. He added that nutrient control measures could include reducing fertilizer use, improving water treatment plants and closing illegal wells that are decreasing inputs of clean water to the wetlands.
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. While the Brazilian government has dramatically curtailed deforestation, further efforts to slow the damage from logging and quickening forest regeneration could protect the forest from fire, maintain regional rainfall and thus prevent a drastic ecosystem transformation.
The Great Barrier Reef is threatened by 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.
The authors argue that there may be more effective incentives associated with local action than with any global effort to mitigate global warming. “Mitigation requires global collective action and is vulnerable to free riding,” they said, “whereas adaptation can be done unilaterally, with benefits accruing almost exclusively to the country doing the adaptation. However, iconic ecosystems also provide a global public good.”
“Creating a Safe Operating Space for Iconic Ecosystems” will appear in Science on March 20, 2015.