World's Most Iconic Ecosystems May Collapse Under Climate Change

Researchers warn that without better local management, some of the world's most iconic ecosystems may collapse under climate change.

It is well known that corals in the Great Barrier Reef, for example, are diminishing due to ocean acidification, and that the Amazon rainforest has been suffering from drought over the last decade. But in order to combat such climate change-related threats, we need to reduce the other pressures they face - for example, overfishing, fertilizer pollution or land clearing.

That's at least according to new findings published in the journal Science.

"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," the study's lead author Marten Scheffer, chair of the Department of Aquatic Ecology and Water Quality Management at the Netherlands' Wageningen University, said in a press release.

The research team examined three UNESCO World Heritage Sites: Spain's Doñana wetlands, the Amazon rainforest and the Great Barrier Reef. While many ecosystems are indeed important to the environment and to their local people, these ecosystems in particular have a global importance.

Coral reefs have gained a lot of attention recently due to the effect of ocean acidification - the increase in acidic waters due to buildup of atmospheric carbon dioxide - that have led to extensive bleaching events. Worse still, studies have shown that ocean acidification is eating away at the structural integrity of these unique marine animals, causing coral to become more susceptible to both predators and disease.

In fact, the Great Barrier Reef's growth rate has plummeted by 40 percent since the mid-1970s.

But overfishing, nutrient runoff and unprecedented amounts of dredging are exacerbating these climate change-related threats. By eliminating these stressors, the Great Barrier Reef may have a chance in our warming world.

However, like corals reefs, rainforests and wetlands around the world are also under increasing pressure from both climate change and local threats.

Such local threats include nutrient runoff from the use of agricultural fertilizers and urban wastewater, which is degrading water quality in the Doñana wetlands in southern Spain. This, in turn, is causing toxic algal blooms that endanger the ecosystem's biodiversity.

A warming climate could encourage more severe blooms, causing losses of native plants and animals, researchers say. This ecosystem is a vital wintering site for waterfowl - hosting over half a million birds - and home to numerous unique invertebrate and plant species.

"Local managers could lessen this risk and therefore boost the wetlands' climate resilience by reducing nutrient runoff," explained co-author Andy Green, a professor at the Doñana Biological Station.

To reduce nutrient runoff, he added, managers could reduce fertilizer use, improve water treatment plants, and close illegal wells that are decreasing the flow of clean water to these wetlands.

When it comes to the Amazon rainforest, rising temperatures and severe dry spells, along with deforestation, are major threats to its survival. This deadly combination could turn the ecosystem into dry, fire-prone and species-poor woodland. The United Nations has pledged to end deforestation completely by 2030, which no doubt would help. But researchers also recommend curtailing canopy damage from logging and speeding up forest regeneration. These management efforts could protect the forest from fire and maintain regional rainfall, helping the Amazon to thrive and better resist climate change.

"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," Scheffer pointed out.

"All three examples play a critical role in maintaining global biodiversity. If these systems collapse," he added, "it could mean the irreversible extinction of species."

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