“We had the warmest temperature in Villefranche-sur-Mer, 28.2 degrees and this leads to mass mortality,” says the Intergovernmental Panel on Climate Change (IPCC) contributor Professor Jean-Pierre Gattuso in this episode of Ocean Calls.
The scientist describes a marine heatwave that hit the picturesque French Riviera this summer.
“Approximately 20 per cent of the coastal zone between the surface and ten-metre depth is lost.”
“In 2015 we had 80 per cent mortality of the coral reefs in the southern Red Sea, and they haven't recovered yet, seven years after,” says Prof Carlos Duarte, a marine ecologist at the King Abdullah University in Saudi Arabia, our second guest on this episode.
In 2020, the two scientists co-authored a paper ‘Rebuilding Marine Life’ in the journal Nature, in which they listed five main actions to take in order to restore the abundance of marine life lost to human activity and climate change.
First, the actions needed to protect species. Second, spaces - the so-called Marine Protected Areas, then removing pressures on the ocean and addressing climate change “with a high level of ambition”.
“Then it's also to harvest wisely and to remove pollution,” Duarte highlights.
A helping hand from humans
Coral reefs are one of the richest ecosystems on Earth. Home to a quarter of all marine life, they also protect communities on land and offer an invaluable source of food.
Mangroves and seagrasses, just like trees, absorb carbon dioxide from the atmosphere and sequester it helping us fight climate change. But all of these ecosystems are in grave danger. According to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), 66 per cent of our oceans are impacted by human activities.
Duarte believes that in order to recover, nature needs humans to be actively involved.
“If we just protect the spaces, but we allow the recovery to happen without assistance from humans, that is going to be much slower than if we actively engage in giving a helping hand to nature,” he says.
While there are effective ways to restore mangroves and sea grasses, coral reefs present a bigger challenge as the success rate is often as little as 10 per cent, Duarte points out.
“So the emerging concept is that we don't just do restoration with randomly collected corals or the same corals stock that was actually wiped out by the heat wave,” he says, explaining that these corals will not survive the next heatwave.
Instead, the scientists suggest using marginal corals “that don’t look like much” but that were able to survive in the waters of poor quality.
Gattuso believes that the existing restoration efforts are not enough to turn back time.
“I'm not convinced by the scale of the operation,” he says.
“I'm sure it will lead to major developments both in science and technology. But how are you going to restore hundreds of kilometres square kilometres of reefs, you know?”
According to Gattuso, restoring nature isn’t enough to fight climate change and a bigger effort is needed.
“There are countries that prefer to invest in the blue carbon ecosystems, like increasing resilience of coral reefs such as Australia. And at the same time increasing tremendously the mining of coal,” he says.
“You cannot do both. You need to cut down on the use of fossil fuels,” Gattuso insists.
So, what can be done? Can we repair the damage? Can these and other precious ecosystems like seagrasses and mangroves not only be preserved, but also actively restored?
To answer these questions we’re talking to Prof Carlos Duarte, Executive Director of the Coral Research & Development Accelerator Platform, also known as CORDAP and an ocean acidification expert and IPCC contributor, Prof Jean-Pierre Gattuso, research director at the Laboratoire d'Océanographie de Villefranche-sur-Mer.
And at the end of the episode, you’ll hear from Mission Blue founder and legendary oceanographer, a pioneer in the use of modern scuba gear, Sylvia Earle.
Created in partnership with the European Commission's DG Mare.