‘Blue carbon’ pioneer receives prestigious Japan Prize

The professor who coined the term ‘blue carbon’ to describe the carbon stored in oceans and coastal ecosystems has been awarded the 2025 Japan Prize, one of the world’s most prestigious international awards in science and technology, second only to the Nobel Prize, for his groundbreaking contributions to marine and coastal ecology research.

Carlos M Duarte, Ibn Sina Distinguished Professor of Marine Science at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, pioneered research on the crucial role of blue carbon ecosystems as a nature-based climate solution, transforming the world’s understanding of ocean ecosystems and their potential to address global environmental challenges.

Duarte, who is originally from Portugal, received the Japan Prize at a ceremony in Tokyo in April, presided over by Japan’s Emperor Naruhito. With two laureates named each year, it honours exceptional achievements that contribute to global peace and prosperity.

The Japan Prize citation said: “Duarte’s research has shed new light on the functions provided by marine ecosystems and argues that harnessing those functions could allow us to mitigate global warming and other global environmental issues.”

While covering only 0.2% of the ocean floor, these ecosystems store approximately 50% of all carbon buried annually in marine sediments.

The Japan Prize statement said: “The role played by vegetated coastal habitats was still unknown when Duarte released his research, and it shocked the world.

“A 2009 United Nations Environment Programme (UNEP) report listed Blue Carbon as a new option for addressing global warming alongside Green Carbon, or carbon absorbed by terrestrial plants, and it pointed out the particular importance of vegetated coastal habitats as carbon sinks.”

Duarte said he was approached in 2009 by different United Nations agencies to write a report to convey to policymakers the importance of avoiding the loss of these coastal habitats and conserving them – in addition to land-based habitats. It was in this report, Blue Carbon: The Role of Healthy Oceans in Binding Carbon, that he first used the term ‘blue carbon’.

Recognition of the importance of blue carbon

In an interview with University World News Duarte said his work demonstrates how universities with focused funding and international research networking can collaboratively contribute to tackling crucial global climatic concerns.

The term ‘blue carbon’ relates to marine ecosystems that are coastal habitats. Restoring habitats that are damaged and avoiding further loss can mitigate climate change, he said.

When climate change was first recognised as a major risk and threat to global society around the 1980s and 1990s, the focus was on preventing land-based deforestation and restoring degraded forests.

“The focus was on land for a long time,” he explained. “Towards the end of the past century, my research showed that ecosystems on the margins of the shorelines – the coastal habitats like mangroves, sea grasses and salt marshes – are also very intense carbon sinks that had been ignored to date in terms of [being] allies to fight climate change,” he noted.

Duarte said that “every 100 years or so”, major wildfires destroy large tracts of forest somewhere, grabbing global headlines.

“The key differentiator is that there are no fires underwater, so the carbon deposits in the ocean are not at risk of being emitted again to the atmosphere due to fires.

“And there is no oxygen, and that really prevents the microbes from being able to degrade the carbon. Therefore, there’s a lot more carbon stored, and it is safely stored over millennia," he noted.

“Much of my fieldwork on blue carbon addresses impacts in the Red Sea and the Arabian Gulf. And in fact, we are discovering new processes through our research in the Red Sea,” he stated.

“We also do a lot of work on understanding the genomics of mangroves and seagrass and the elements of the ecosystem that maintain their health,” he added.

He said researchers such as himself have partnered with conservation organisations in Saudi Arabia, where he conducts most of his work. Today, the Gulf area has the world’s longest-running mangrove restoration programme, started by Abu Dhabi in the 1970s.

Protecting coastal mangroves saves lives

Duarte said the disappearance of mangroves in Southeast Asia – which has some of the largest mangrove and seagrass stalks in the world – is a major environmental issue that universities and government agencies have only recently begun to become aware of.

“It’s very easy to bring that conversation to Southeast Asia because Southeast Asia holds some of the largest mangrove stalks and seagrass stalks in the world, particularly Indonesia, but also Malaysia, and the Philippines. Other nations in Southeast Asia also have a lot of blue carbon resources,” he noted.

During the 2004 Asian tsunami, countries in Asia that had preserved their mangrove shorelines found that these protected coastal communities by acting as a buffer against waves and saved lives.

Thus, after Duarte’s blue carbon report was published in 2009, they were the first nations to embrace ‘blue carbon’ as a strategy.

“They were not driven by climate change; they were driven by restoring the capacity of the habitats to protect the shorelines. Now Indonesia is one of the champions of blue carbon,” Duarte said.

“Blue carbon has become probably the first instance of nature-positive economies. Maintaining healthy mangroves is very important, not just for climate but for protecting the human lives that thrive behind the mangroves,” he explained.

Saudi Arabia has a strong collaboration with Indonesia. Duarte is working closely with a new institution called the Blue Institute, which aims to protect coastal and marine natural assets by converting them into economic assets.

It “has a number of concessions in Indonesia to promote a regenerative new blue economy of which blue carbon is a component,” Duarte said.

Blue carbon in the Red Sea

Explaining some of his work in the Red Sea area, he said: “We discovered a new mechanism – we published it in our university (journal) – by which these habitats contribute to climate removal, not just [by] storing organic carbon in the soils.

Mangrove roots growing in carbonate soils can release acids which dissolve the carbonate, and that releases alkalinity into the water, he said. That release “shifts the chemical equilibrium of the carbon system and binds carbon dioxide into bicarbonate that is stable in the ocean for thousands of years”.

Earlier this year, Duarte led the first scientific expedition from Saudi Arabia to Antarctica to investigate how whale populations contribute to carbon sequestration and thus mitigate climate change as the populations recover.

The team collected samples from the continent, which they say will provide the first quantitative measurements of the impact of whales on carbon capture and climate change.

New ecosystems

While data indicates that many blue carbon ecosystems have already disappeared – 35% of mangroves are estimated to have been lost in the 1980s and 1990s alone – advanced technologies and experiments have uncovered previously unknown ecosystems.

For example, by attaching sensors to sea turtles to observe their foraging patterns, Duarte and his research team found many new seagrass meadows that increased the known seagrass area in the Red Sea by more than 10%.

“We used turtles to map the seagrass because they go to feed on them. So, when we tracked them, we saw where they were feeding, and we discovered 30 new seagrass meadows,” Duarte said.

In the Bahamas, Duarte and his team fitted cameras to sea sharks to film the seafloor. This research resulted in the discovery of the world’s largest seagrass ecosystem, one of the world’s largest carbon sinks, which was mapped over 92,000 square metres. The team’s findings were published in the scientific journal Nature Communication.

Recently, Duarte was commissioned by UNESCO to assess their 50 World Heritage marine sites.

“We found that these 50 sites held about one-third of the total blue carbon resources of the ocean, even though they represent less than 10% of the shoreline of the globe. UNESCO is rolling out an initiative to fund the conservation efforts, especially in poor countries,” said Duarte.