The survival of coral reefs requires a radical rethink of what conservation means, as well as embracing some of the changes they are undergoing, according to a paper by leading coral reef scientists.
“Helping coral reefs to safely navigate the Anthropocene is a profound challenge for multiscale governance,” the scientists say in a paper published today in the journal Nature.
They argue reef conservation must no longer be seen as an attempt to restore reefs of the past, or conserve their existing values, but rather to identify the parts of reefs that are essential to their continued existence, and protect those.
The paper comes amid increased urgency from conservationists and reef managers around the world, sparked by the worst global bleaching event in recorded history. It caused mass die-offs in every major coral reef region of the world. On the Great Barrier Reef alone, it is estimated that about half the coral was killed in 2016 and 2017.
In the paper, the scientists argue saving the world’s reefs requires the acceptance that the reefs of the future will look very different to those of today, and humans may need to help them adapt – perhaps by intervening to increase the proportion of coral species that are tolerant to rising temperatures.
“In the coming centuries, reefs will run the gauntlet of climate change, and rising temperatures will transform them into new configurations, unlike anything observed previously by humans,” the paper says.
But the overall message was one of hope, said lead author of the paper Terry Hughes from James Cook University in Australia.
“There’s no shortage of people saying reefs will be dead by 2030 or whatever,” Hughes said. “They are going to be different systems with a different mix of species but if we throw the kitchen sink at it and especially deal with climate change then we will have functioning reefs that will sustain and repair themselves and be of some use to people,” he said.
The group of scientists, which includes both biologists and social scientists, argue the approach to reef conservation must change in several ways.
As coral reefs change, the authors say scientists and conservationists must focus on aspects of reef ecosystems that are the most important to their continued existence. They say biodiversity is no longer the most important value to protect, since some species are more important to the ecosystem than others.
They also suggest that helping reefs adapt may become an important strategy. “Ecosystem composition change is already occurring naturally, as corals respond and adapt to climate change, and could be promoted further through efforts to actively manipulate ecosystem configurations,” they write.
Besides embracing the fact that reefs will never be the same, they argue research and conservation must shift from the most direct impacts on reefs, and instead identify and target the root causes.
For example, rather than focusing just on the role herbivorous fish play in suppressing seaweed, thereby allowing reefs to recover, conservation efforts should focus on what drives the overfishing of those fish – such as poverty and market demands. “We tend to propose bandaids rather than dealing with the root cause of the issue,” Hughes said.
Underlying the finding that reefs will continue to survive is the assumption that agreements made at Paris to keep global warming to “well below 2C” are successful.
The researchers reviewed published experiments that examined the response of coral to rising temperatures, and found none that looked at the carbon dioxide levels they say reefs are likely to experience over the next century. Instead, those studies universally examined much more extreme scenarios, equivalent to several degrees of global warming.
“Most of the coral reef literature assumes business-as-usual emissions to the end of the century, which would result in global warming of 4, 5 or 6C,” says Hughes. “We will never get there – not because people will become more and more concerned about coral reefs – but because Florida will go under water and that will get people’s attention.”
Similarly, the authors said experiments examining the impacts of acidification looked at exaggerated scenarios, and the researchers said there were some suggestions acidification may not have a large impact on the growth of coral.
The understanding that coral reefs will never be the same is already affecting management practices around the world.
In Australia, the Guardian revealed last week that advisers to the government’s plan to protect the Great Barrier Reef have said it must stop trying to “improve” and restore the natural heritage values, and instead should aim to “maintain the ecological function” of the reef, while accepting its overall health would inevitably decline.
Similarly, sources have told the Guardian that discussions are occurring within Unesco, over how to protect natural heritage values, given that climate change means many heritage sites will inevitably be altered.
Not all coral reef biologists are supportive of efforts to manipulate reef ecosystems.
Justin Marshall from the University of Queensland said the new paper made many good points, but that he did not think attempts to pick and choose parts of reefs to save would be successful. “We’re consistently crap at playing God – or playing Darwin,” Marshall said, adding that ecosystems were too complex to predict the outcomes of particular interventions.