Groundwater brimming with excess nutrients and other contaminants is quietly flowing into the ocean, posing a threat to vulnerable reefs. 

By Anna Napolitano, April 22, 2026

Sitting along the Pacific Ring of Fire, the Philippines’ volcanic geology features porous rocks that allow water to move easily underground and flow into its ocean.

These hidden flows – called submarine groundwater discharge – are known to maintain balance in the ocean’s chemistry. But with experts noting that only about 30% of the country’s wastewater is being treated, these flows have an insidious impact.

Submarine groundwater discharge (SGD) is a natural process driven by a mix of climatic, hydrogeologic and oceanographic forces, often occurring in coastal areas. It is more pronounced in rocky and volcanic regions.

Rivers are another direct link between land and sea, but they are also visible – their freshwater and pollutants more obviously flow into the ocean. SGD, which combines terrestrial groundwater and recirculated seawater, is often more concentrated with nutrients and pollutants, and hidden below the ground.

Research on SGDs has only occurred in the past decade. Scientists now recognise that the discharge of fresh, brackish and marine groundwater into coastal oceans is just as impactful as that of rivers. 

Estimates sourced from the Great Barrier Reef in eastern Australia suggest the total volume of water flowing from the ground into the coastal ocean is greater than river discharge. Moreover, in certain coastal areas, the concentration effects of SGDs result in a nutrient input into the ocean surpassing that of surface water – rivers, lakes and streams. Scientists say this has impacts on the Philippines’ coral reefs, which make up nearly a tenth of the global total.

How SGDs help and hurt reefs

In some contexts, groundwater can support reef systems, delivering the right combination of nutrients at modest levels, or cooling marine heat.

However, rising coastal population densities, changing agricultural practices and ageing wastewater systems impact this balance.

At two small coral islands in the northern South China Sea, researchers found that even a small amount of SGD carries carbon compounds that can degrade the shells or suppress the growth of certain marine animals.

In many coastal areas of the Philippines, harmful algal blooms – commonly known as “red tides” – have become increasingly frequent, with over 44 distinct coastal locations across the archipelago experiencing outbreaks since the first major bloom was recorded in 1983.

“I recall the feeling of the hot viscous layer of water sitting on top of the colder, clear water below, the first time I swam in the Philippines,” says Amelia Wenger, conservation scientist and water pollution programme lead for coral reefs at the Wildlife Conservation Society, describing an algal bloom.

Scientists link red tides to a combination of climate change and eutrophication – where an overconcentration of nutrients stimulates excessive algal growth. SGDs are increasingly recognised sources of these nutrients, which include nitrogen, phosphorus and dissolved silica.

“The science shows very clearly that wastewater is one of the two big killers of coral reefs … in Hawaii and in other places in the world,” Greg Asner, director of the Center for Global Discovery and Conservation Science at Arizona State University, said in a radio interview in January. “The only other one that’s competing with wastewater is climate change. And when the two combine, it is a terrible mix.”

In many island territories, porous volcanic rock or limestone’s high permeability limits the soil’s natural filtration capacity, allowing rapid transport of water and pollutants. Private houses and holiday resorts alike often rely on private cesspools or septic tanks in these territories, where sewage systems are typically insufficient or non-existent. These simple holes, or containers in the ground, collect the wastewater but are often badly sealed. They use some form of chemical treatment but are often outdated, poorly maintained or vulnerable to flooding, allowing contaminants to seep into groundwater with minimal intervention. From there, pollutants travel unseen to coastal waters, with consequences ranging from coral disease to unsafe swimming conditions.

A study on the reefs around Santiago Island in the north-western Philippines found that groundwater emerging beneath reef flats had nutrient concentrations much higher than those of normal seawater. In other sites, such as the resort island of Boracay, researchers found residues of caffeine and painkillers travelling from land to sea via groundwater. These results clearly point to untreated wastewater, especially in busy tourist areas.

“Contaminants can also be agrochemicals and petrochemicals, and science barely knows the impacts of the huge range of those chemicals,” Asner said in an email interview with Dialogue Earth.

Wastewaters threaten the coral triangle

In Metro Manila, the Philippines’ largest metropolitan area, less than 15% of the city’s population is connected to a sewage system. From the majority of households, untreated waste flows directly into rivers or leaks into the ground. From there, they are an easy reach to Manila Bay, a natural harbour on the western border of the region.

The bay is now heavily polluted from household wastewater, with faecal contamination far exceeding safe limits – a hallmark of the faulty human waste system.

Amid mounting water pollution and these high levels of faecal bacteria, in 2025 the Metro Manila Development Authority, alongside the Department of Environment and Natural Resources and the Metropolitan Waterworks and Sewerage System, began drafting a plan to expand sewerage infrastructure. Their target is to service around 80% of the national capital region by 2047. Early progress has been visible: Manila Water, the main concessionaire involved, added over 43,000 new sewer accounts in September 2025 alone.

However, SGD remains largely absent from policy frameworks.

“We know that SGDs play a key role in marine pollution,” Von Hernandez, vice president of the conservation NGO Oceana Philippines, tells Dialogue Earth. “We need governments to add it to their priorities for research and investigation, to make the issue more visible to the public so that appropriate actions could be taken.”

High stakes

Researchers are pushing to change that. “There is not enough attention from policymakers in the region on the phenomenon, and that tells us that there is still much work that needs to be done,” says Fernando Siringan, research professor at the University of the Philippines’ Marine Science Institute.

His team discovered storms and heavy rainfall events can temporarily boost groundwater flow into the ocean for several days after the event. As climate change intensifies storm events in the region, the pulse of pollution could become more dynamic and less predictable, adding another layer of concern.

“Coral reefs are already suffering from climate change consequences. Polluted hidden effluents are increasing the impact,” Siringan tells Dialogue Earth.

For coastal countries reliant on healthy reefs for fisheries, tourism and shoreline protection, the stakes are high. Reef degradation lowers fish stocks, reduces tourism and causes significant income declines for coastal households. For example, the six-month closure of the Philippines’ tourist gem Boracay in 2018, due to environmental degradation, was projected to have affected over 36,000 workers and caused losses of nearly USD 1 billion. Beyond tourism, over 2 million people work directly or indirectly in the country’s fisheries sector.

“An invisible problem is becoming visible,” says the chemical oceanographer Gil Jacinto. A 2024 global meta-analysis of coastal groundwater nutrient concentrations identified SGD as a significant source of nitrogen and phosphorus in the ocean of many coastal areas. Yet it is rarely included in official nutrient budgets. These budgets balance the input, output and storage of such nutrients, making them critical to identifying sources of eutrophication.

“There is good data and evidence that SGD pollution affects coastal environment health in the Philippines. Still, most policy responses here only focus on river discharge, while the contribution of SGD remains largely unaccounted for,” Jacinto tells Dialogue Earth.

From mapping pollution to integrated solutions

As evidence mounts, local communities and scientists in island territories are pushing to integrate SGD monitoring into environmental management at tourist sites – a first step toward recognising groundwater as part of the land-sea pollution continuum.

One example can be found in Hawaii, where researchers from Arizona State University including Asner worked with the ʻĀkoʻakoʻa Reef Restoration Project. The team mapped over 1,000 locations where groundwater contaminated with faecal bacteria enters reef systems on the western coast of the state’s largest island. This data is now informing policymakers when considering new land reformation efforts, wastewater infrastructure upgrades, and community-led efforts to replace cesspools and repair septic systems.

“When I started working on pollution issues, there weren’t that many people who were interested,” Wenger tells Dialogue Earth. “In the last five years, there’s been a real shift. The more we know about it, the more we can raise awareness and adapt solutions for other countries.”

Wenger is now developing guidance for the sanitation and production sectors (agriculture, livestock and aquaculture), with plans to expand this to encompass plastic pollution, coastal erosion and urban runoff.

This follows from a previous guide and toolkit she and her colleagues developed to help conservationists and sanitation workers reduce wastewater pollution. Released in 2024, the toolkit includes factsheets to help such professionals diagnose, assess and monitor specific types of pollution within their systems, and to design ad hoc solutions.

“I split my time talking to ocean people and then talking to sanitation people about what they both need to think about pollution. Coastal communities are generally receptive, especially when shown that reducing wastewater pollution directly benefits local reefs, fisheries and public health,” she says. “But often the high costs are a limitation. Working alongside the WASH [water, sanitation and hygiene] sector can help on this front.”

She adds: “I wish we’d started this 20 years ago, but we didn’t. Here we are now, and we’re thinking about the solutions.”

Submarine groundwater flows might be invisible, but their impact is not. As scientific understanding deepens, researchers say governments must widen their scopes beyond rivers and pipes and confront the hidden currents shaping coastal systems.

Anna Napolitano

April 22, 2026 

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Experts question whether overseas assistance can make any difference to a cycle of failed projects and stalled ambitions. 

By Annie Banerji, April 20, 2026

India has one of the world’s longest coastlines, some of the most ambitious renewable energy targets, and a looming net zero deadline. Yet it does not have a single offshore wind turbine to show for years of effort.

Government figures hope this will change after India and the United Kingdom launched a taskforce in February, which they have dubbed a “trustforce”. It has been charged with developing an offshore wind ecosystem, supply chains and financing models.

Writing after the launch, India’s minister for new and renewable energy, Prahlad Joshi, said: “With the UK’s experience and India’s scale, this trustforce will deliver measurable outcomes for energy security and sustainable growth.”

The UK is a global leader in offshore wind energy, along with China, Germany, Denmark and the Netherlands. It hosts several of the world’s largest offshore wind farms, including the vast Dogger Bank and Hornsea sites. The country plans to triple capacity over the next decade, with a target of up to 50 gigawatts (GW) by 2030.

India, one of the top emitters of greenhouse gases globally, wants to build 500 GW of what it calls “non-fossil fuel based energy resources” by 2030. This target includes 30 GW of offshore wind capacity. India has also pledged to reduce its carbon emissions to net zero by 2070.

India had 272 GW of installed electricity capacity from non-fossil fuel sources as of February, including 141 GW of solar and 55 GW of onshore wind. But the country remains largely reliant on coal. As of 2023, 46% of India’s energy was supplied by coal and coal products, according to the International Energy Agency.

“As we move towards net zero, we will have no option but to go into offshore wind. We can’t do without it,” Bhupinder Singh Bhalla, India’s former renewable energy secretary, tells Dialogue Earth. “It is very important to start now, so that we develop our expertise, projects start happening, the ecosystem comes in.”

Failed auctions

Back in 2015, India launched a national attempt to harness offshore energy and unlock jobs and investment. It identified the areas offshore of Tamil Nadu in the south and Gujarat to the west as having over 70 GW of wind energy potential between them.

And yet, India has struggled to get a single project off the ground.

In 2024, the government offered 74.5 billion rupees (just over USD 800 million) in so-called viability gap funding (incentives to cover risks for developers) to support the industry. But the first tender, offered nearly a decade after this national push was first unveiled, failed to get bids as India shifted its focus to solar and onshore wind power.

India is not the first country to struggle with offshore wind. Installing farms requires large amounts of money, complex technology and dealing with the huge engineering challenges posed by harsh ocean conditions.

“[Offshore wind projects] rely on a complex ecosystem of seasoned developers bringing lessons from mature markets, specialised engineering contractors, robust supply chains and banks willing to shoulder risk,” noted the London-based energy think-tank Ember last year. “So far, this has proved elusive in India, which is why even the best-intentioned policies and auctions have failed to translate into active projects.”

Duttatreya Das, who co-authored that analysis, points to design flaws in India’s tenders. He explains to Dialogue Earth that the government fixed both the buying price and the subsidy it would offer, but those two together do not cover the actual cost of generating offshore wind power.

“The central government also has a limited kitty and has to balance across sectors,” Das adds. “So, there’s a gap, and if the cost of generation is significantly higher, no one [in the energy sector] wants to put in money from their own pocket to cover it.”

The Ministry of New and Renewable Energy (MNRE) has not responded to repeated requests for comment.

Bhalla, who led the ministry when the first tenders launched in February 2024, said the structure India came up with for its offshore plans “was not as attractive to investors as we assumed it would be”.

He points to several reasons for this failure: international developers were reluctant to take on the added risk of working in an unfamiliar market; India’s project timelines required completion within four years, against a global norm of six to eight; and the viability gap funding was not generous enough.

Bhalla, who has spent years working in government, adds it was likely the new taskforce is more a political deliverable after a bilateral meeting, rather than a considered policy initiative.

“That’s not necessarily wrong,” Bhalla says. “My only worry is how long it will take, and whether it gets converted to actionable projects. I do not want it to just exist on paper. There should be positive results out of this kind of taskforce.”

A dud Danish deal?

The UK deal is not the first time India has looked abroad for offshore wind help. In 2019, it signed an agreement with Denmark to develop the industry.

Das worked on that deal. The experience makes him sceptical of the India-UK taskforce, and of India’s wider offshore ambitions:

“The Denmark programme is the one that actually started discussions that led to tenders and to a lot of data collection and awareness around offshore wind. And even after all that, it did not work out. This, by comparison, is very superficial. I won’t be surprised if nothing translates into real action.”

Denmark continues to work with India on the technical aspects of offshore wind, but the initial, commercial aims of the partnership did not materialise, says Das. In February, the MNRE insisted the UK-India taskforce was not a “symbolic platform” but a “working mechanism” that would address real execution challenges.

Dialogue Earth consulted Ivan Savitsky, a senior manager of the offshore wind team at the environmental sustainability consultancy, Carbon Trust. He says the UK could help India with technical know-how on market design, and support India with risk allocation. He also says there may be opportunities for supply chain partnerships between UK and Indian companies.

The UK uses a two-stage auction process for offshore wind projects, which separates seabed leasing auctions from electricity generation auctions. The two stages are managed by separate authorities, the latter being the UK government, which secures the income stability for electricity providers that helps make these projects bankable.

“For new markets like India, an important lesson is to respect the level of maturity of the industry in an individual market,” Savitsky says. “The key learning, both from the successes and the challenges, is being flexible with policy and being reactive to actual industry conditions. For new markets, that’s especially important because there are different risks – new political risks, new local risks around project delivery, community engagement, and so on.”

A neighbour that solved the problem

The UK is second globally for installed offshore wind capacity. The leader, by a huge margin, is India’s neighbour and regional rival: China.

China’s immense domestic demand is fuelled by the government’s wind power targets, which have enabled a huge industry to grow. But while China leads the world in manufacturing, exports remain limited. European turbine makers are dominant beyond China, but the latter is aiming to increase its exports.

Despite political tension between the two nations – including a border dispute that flares into violence – China already sells wind power technology into India’s healthy onshore sector. Some Chinese firms even have local factories.

The Indian government has been pushing a “Make in India” agenda to boost domestic industries but remains heavily dependent on Chinese companies for many renewable technologies.

Is it worth it?

Ember’s Das wonders whether offshore wind is worth it for India, given solar energy is currently so affordable and easily scalable: “Why invest in a costlier solution when you have a cheaper alternative?”

He adds that offshore wind projects, which require everything from big ports and roads to underwater cables, could face further problems by disrupting local livelihoods and ecology. “I don’t think offshore wind will ever stand a chance in India in pure economic terms. It will never be cost-competitive.”

Others think offshore wind is not only worth the investment, but essential.

“To have a proper bouquet of energy sources, it’s good to have wind, which is a natural provider of grid stability: solar is the daytime; wind is typically evening and morning. So, they together allow maximum utilisation of the grid,” argues Bhalla.

He wants the government to rework its tender design to make it more attractive for international players, offering bigger projects and more funding:

“I am disappointed the ministry has not resolved this by now. It is not rocket science. You just sit with the industry and ask: what is the problem? Talk to them, revise the norms and come back. That should have happened already.”

In the decade since its national wind plan, India has not placed a single turbine offshore. Advocates say India cannot afford another decade of the same.

Annie Banerji

Bird-pond tourism is raising rural incomes and awareness of threatened species, but scientists say regulation is needed to manage ecological risks. 

By Mike Shanahan, April 21, 2026

In November 1989, Chinese farmer Hou Tiguo was hunting birds with a slingshot near his home in Baihualing, a remote village in subtropical Yunnan province, when a chance encounter changed his life.

He met two tourists from Taiwan who offered to pay him to show them wild birds. Hou accepted, and by the end of the day they had seen 160 bird species.

The tourists told Hou that if the villagers stopped hunting birds, many more people would come to see them. Birdwatching was almost unknown in China at that time. But word of Baihualing’s rich birdlife spread, visitors did begin to arrive, and Hou became one of the country’s first bird guides. For two decades, he supplemented his farming income by guiding, until he had an idea that would bring birdwatchers – and money – pouring into his community.

Hou had noticed birds visiting a puddle created by a leaky pipe. Using corn stalks, he built a crude shelter, barely big enough for two people, and began charging birdwatchers CNY 20 (USD 2.80) each to use it. ‘Hide-in-bird-pond’ tourism was born. Before long, Hou had created several artificial ponds, with more sophisticated and spacious hides. Other villagers followed his lead, transforming Baihualing’s economy.

Today, more than 250 hide-in-bird-ponds operate across China, with scope for many more – according to a new nationwide assessment. Its authors say they offer significant potential to boost rural incomes and protect biodiversity, but warn that unregulated growth could bring ecological and socioeconomic risks.

A new model of birdwatching

The set-up is simple. Operators provide shallow pools of water and food such as fruit or insect larvae. Birds arrive to feed, drink and bathe. Nearby, birdwatchers and photographers wait in camouflaged hides, often just metres away, for close-up views of the birds. At some sites, meals are delivered, so clients don’t need to leave.

“Whenever possible, we take our guests to bird hides,” says Summer Wong, who runs Summer Wong China Bird Tours which is based in Sichuan. “[Hides] allow them to observe certain target species that are otherwise very difficult to see in the wild, quickly and efficiently. Such wildlife-focused tourism provides a valuable source of income for local communities, encouraging them to protect the birds rather than hunt them.”

Baihualing was an ideal place for the model to take off. The village sits at 1,400 metres on the eastern slope of Gaoligong Mountain, part of a mountain range that has one of the world’s greatest concentrations of bird species. The village is a gateway to the forested slopes of the Gaoligongshan National Nature Reserve, an important area for biodiversity. Around Baihualing itself, 474 bird species have been documented.

Birdfinders, a UK-based tour company, says on its website that Baihualing’s ponds attract a “dazzling array” of birds, including laughing thrushes, scimitar babblers, sibias and minivets. “The views here are far superior to anything we could hope for along the trails,” it notes.

Baihualing’s boom

Before bird ponds, Baihualing was impoverished, with per-capita incomes of about CNY 3,000 (USD 430) in 2008. By the early 2020s, incomes had more than quadrupled. But as birdwatching took off, the number of ponds grew rapidly, reaching more than 70. A case study published in 2024 by Yunnan’s Department of Natural Resources describes how local authorities intervened to standardise operations and reduce pond numbers, leaving around two dozen higher-quality sites.

Today, thousands of birdwatchers visit Baihualing each year, stimulating a wider seasonal economy of guesthouses, restaurants, transport services and cultural activities. The case study estimated that tourism engaged a third of the village’s population and generated more than CNY 8 million (USD 1.1 million) in annual revenue, while also contributing to a reduction in poaching and indiscriminate logging.

A key innovation has been a village-level benefit-sharing system. Previously, tensions arose between farmers who wanted to clear forest for crops and bird pond operators who wanted trees left standing. Now, revenue from bird pond tickets – currently CNY 70 each (USD 9.8) – is distributed among bird pond owners and other groups of villagers, under an agreed formula.

“It unites all villagers to take collective actions to protect birds,” says Xinran Wang of the Shenzhen College of International Education, whose research on the Baihualing birdwatching industry was published in October 2025.

“Everyone has the incentive to remain in the organisation: bird pond owners can sustain their profits without obstacles from farmers; other villagers can receive extra dividends,” she told Dialogue Earth. “This formed a cycle to continuously bring positive effects.”

Baihualing’s trajectory underscores both the promise of bird-pond tourism – and the risks that emerge when expansion outpaces regulation.

A national phenomenon

Hide-in-bird-pond tourism has spread rapidly across China, often built around “star” bird species. In Yunnan, Shiti village entices visitors with three species of hornbills. In Qinling, Shaanxi province, birdwatchers flock to see the endangered crested ibis. In Mangba villag, Yunnan, a population of 300 Derbyan parakeets attracts many tourists. In December 2025, China Daily cited reporting by China Green Times that bird tourism there generates over CNY 4 million (USD 560,000) a year in the village of just 250 residents.

But the industry has grown organically, without national guidelines, formal oversight or science-based standards. Concerns include the possible ecological impacts of supplemental feeding and the risk of disease transmission, both among birds and between birds and people. A lack of comprehensive monitoring means it is impossible to tell if, overall, the bird ponds are positive or negative for biodiversity.

These gaps prompted Fei Wu of the Kunming Institute of Zoology and colleagues to undertake the first nationwide assessment of hide-in-bird-ponds, published in the March 2026 edition of Avian Research. By analysing online birdwatching forums, they identified 251 hide-in-bird-ponds across 24 provinces, and interviewed all 98 people operating them.

The assessment found that a total of 524 bird species – about one-third of China’s avifauna – have been recorded at these sites, including 152 species classified as threatened or protected. Most ponds (87%) are in economically deprived areas, and nearly three-quarters are within five kilometres of a national park or other protected area.

Wu and colleagues say this highlights the potential of bird-pond tourism to both address poverty and conserve biodiversity, particularly in regions “where ecological priorities and socioeconomic needs intersect.” With 40% of China’s hide-in-bird-ponds located in Yunnan, Wu’s team says there is considerable scope for expansion, especially in other areas with high bird diversity such as Guangxi, Guizhou, Inner Mongolia and Xizang.

Demand is also rising. The number of birdwatchers in China has grown from an estimated 600 in 2000 to 340,000 in 2023. As Wu and colleagues note, this is still less than 0.03% of China’s population.

Risks and regulation

“It is exciting to see this expansion in community-based avitourism in China facilitating connection with nature along with all its wellbeing benefits, and hopefully driving more pro-environmental behaviours among participants,” says Alexander Lees, Reader in Biodiversity at Manchester Metropolitan University. “The benefits for the birds themselves are less clear.”

Lees warns that a proliferation of feeding stations could increase disease transmission or raise predation risk. “It is unclear if these ventures lead to more substantial additional habitat protection,” he adds.

Xinran Wang’s research in Baihualing revealed that some bird pond owners lack knowledge of birds or attempt to discourage common species in favour of more profitable “star birds”. She also documented anecdotal accounts of some birds changing their behaviour or becoming desensitised to people.

“The most urgent step is formal legislation to ensure birds are safe while still leaving villagers some freedom to make profits,” says Wang. Training, she adds, could prevent unintentional harm caused by a lack of awareness.

Bird pond management relies largely on operator experience, says Wu. His team is now developing local standards for constructing and operating ponds and hides. They are also researching the ecological impacts of operations.

The researchers call for national standards and ethical guidelines, formal regulatory oversight with a registry of ponds, systematic monitoring and policy incentives to balance regional development. Without such measures, they warn, rapid and unstructured growth could undermine the principles of ecotourism and threaten the model’s sustainability.

The future of China’s bird-pond tourism, the scientists say, depends on turning grassroots innovations into a system with clear standards and safeguards. But Wu remains optimistic.

“I personally hold great confidence in the potential of hide-in-bird-pond to advance biodiversity conservation and poverty alleviation efforts in China,” he told Dialogue Earth.

“The number of birdwatchers in China will continue to grow, the birdwatching market will expand, and the income of hide-in-bird-pond operators will gradually increase. This will incentivise operators to proactively protect birds and their habitats.”

One-third of projects may have gone ahead even without the credit revenue, new research reveals. 

By Christian Shepherd, April 21, 2026

Methane is behind around 30% of the rise in global temperatures since the Industrial Revolution. The largest share of emissions comes from agriculture, primarily livestock digestion and the decomposition of manure and other organic matter. In China, the energy sector is the largest source, with agriculture a close second.

Emissions offsets designed to curb farmyard methane via improved manure management used to be rare. Only about two projects were proposed per year in 2006 to 2021. Then interest surged. Around a hundred new projects applied for inclusion in markets between 2022 and 2024, according to public registries.

The vast majority of those were pig farms in China, which promised to replace open-air slurry pits with waste management systems that capture and reuse methane to produce heat, electricity or fertiliser.

Credits from these projects have been purchased by a wide range of global buyers, from major oil and gas giants such as Shell and China National Petroleum Corporation, to Chinese battery maker CATL and the University of Melbourne, the registriesshow.

But new research by CarbonPlan, a climate advocacy group based in California, found that nearly a third of the associated carbon credits may not deliver real climate benefits. The findings is part of a global trend of carbon offsets failing to live up to their billing, experts told Dialogue Earth.

Would the projects have happened anyway?

CarbonPlan’s analysis, which has yet to undergo peer review, hinges on the concept of “additionality.” It asks: would this have happened anyway? Projects that need credit revenues to be financially viable are considered additional. But projects that make operational changes because they deliver economic returns without credit revenues – or because such changes are required by local regulations or evolving industry standards – should be considered “non-additional” and excluded from markets.

Out of 74 pig farms in China that stated plans to use captured biogas to generate heat or electricity, 18 projects – or 31% of the potential annual supply of this kind of carbon credit – were “non-additional,” meaning estimated energy generation from biogas saved the farms enough money to make the project financially viable without credit revenue, according to the report.

CarbonPlan calculated their additionality threshold – by comparing self-reported project data on factors such as the number of pigs and heat output from burned biogas against energy cost estimates from the National Development and Reform Commission, China’s state planner.

Four researchers who track voluntary carbon markets or Chinese agricultural policies vouched for the general methodology.

Gold Standard, one of the two credit certifiers that verified the projects, said that it would carefully review CarbonPlan’s report and declined to comment on individual projects or project developers. “Additionality assessments are based on a comprehensive evaluation of financial, technical and operational factors, rather than any single indicator, such as energy self-sufficiency,” the organisation said in an emailed response to questions.

A spokesperson for the other credit certifier, Verra, said the organisation “will look into the specific projects if required” but that the report’s methodology was too broad for the conclusions drawn – applying provincial energy cost averages “across all farms in a province, without accounting for variability in farm size and configuration, fixed electricity costs,” and other project-specific factors.

The findings raise serious questions about widespread lapses in data reliability and quality-control by registries and third-party verifiers, said Grayson Badgley, a research scientist at CarbonPlan who co-authored the article.

“There is strong evidence of non-additionality throughout the carbon market – including renewable energy, forestry, cookstove, and now pig manure management projects,” Badgley said. “Absent serious reform, consumers should treat any environmental claim backed by offsets with scepticism.”

Voluntary carbon markets face credibility concerns

The findings come amid a global reckoning for the voluntary carbon market. Confidence in the value of offset credits has been undermined by widespread accusations of overstated emissions reductions, unverifiable climate claims and fraud. That loss of faith has intensified long-standing complaints of greenwashing by businesses who buy credits to avoid cutting their own emissions.

In 2024, a Dialogue Earth investigation into rice cultivation credits found little evidence of farmers using the advertised methane-curbing irrigation methods. That scandal has continued to reverberate through markets: Climate Home News reported in December that Verra compensated buyers of those bogus offsets with other junk credits.

Standard-setting agencies have tried to restore confidence with stricter quality control. Because methane has 27 to 30 times the atmosphere-warming potential of carbon dioxide over 100 years, methane projects were generally considered higher quality than scandal-plagued credits from forest conservation or rice paddy irrigation.

CarbonPlan’s analysis casts doubt on that assumption. Take, for example, a project comprising eight swine farms in southern Guangdong province. Certified by Gold Standard, the project has since 2021, seen over 700,000 credits issued based on annual emissions reductions of 423,000 tonnes of carbon dioxide equivalent.

CarbonPlan estimated that the biogas-fuelled generators involved in the project would produce enough electricity to meet all project needs, indicating it would likely have gone ahead without climate finance. The savings of nearly CNY 13 million (USD 2 million) per year were absent from financial statements.

Even using the most conservative assumptions, there remained “surprising inconsistencies” between the expected savings and what projects disclosed, the report’s authors wrote. These inconsistencies could be explained in part by shoddy paperwork or projects providing incomplete cost-benefit analyses to verifiers, but even so, the findings raise concerns about the verification process, they concluded.

Voluntary carbon markets that grew out of Kyoto Protocol mechanisms were meant to let buyers fund emissions cuts elsewhere to encourage the adoption of climate-friendly technologies and practices in places that might otherwise lack the finances or incentive to take action. But repeated scandals have increasingly undermined the market’s credibility.

Joseph Romm, a senior research fellow at the University of Pennsylvania Center for Science, Sustainability and the Media, who reviewed the research, said that CarbonPlan’s count looked conservative in light of his review of a growing body of research attesting to widespread overcrediting from multiple project types worldwide.

“It’s endemic and across the board,” Romm said. “The buyer and seller are both incentivised to exaggerate [the climate benefits of credits].”

The usual way to solve concerns of non-additionality is through more robust financial analysis that shows projects are not profitable without credit revenues, said Quirin Oberpriller, an associate partnerat INFRAS, an environmental consulting group based in Switzerland.

That means that the gaps in reporting identified by CarbonPlan are inherently problematic: It “doesn’t make sense” to claim to cut emissions by using biogas but not include the corresponding saving in energy cost in financial statements, Oberpriller said. “If this is the case, it is obviously flawed.”

Incentives, intended and unintended

While pig farms account for a relatively small portion of China’s total methane emissions compared to leakage from coal mines, improved manure management has been identified by the government as an important part of curbing output. In its 2023 methane control plan, the government set a goal of reusing over 85% of livestock manure by 2030.

The agriculture ministry has since at least the 2010s urged farms to implement manure treatment projects to curb water pollution and to reuse biogas, said Fred Gale, a former economist at the US Department of Agriculture. That long-standing push involved a series of subsidised demonstration projects designed to encourage the industry as a whole not to dump slurry in unlined, uncovered pits.

“Farms have been building manure collection or treatment facilities for years, before anyone heard of carbon credits,” Gale said. “I doubt a new farm would be approved without some manure utilisation facility.”

But there may be other drivers behind the sudden increase in farmyard methane credits from China. The uptick also came soon after a major overhaul in the country’s pig farming industry sparked by a severe outbreak of African swine fever in 2018 that resulted in about half of China’s total herd being culled.

Hundreds of backyard farms were closed, as the outbreak accelerated a state-led drive that favoured industrial-scale breeders with modern waste-management systems over smaller operations. Large-scale breeders invested in huge concrete barns that house hundreds of swine, often referred to as “pig hotels” in Chinese media. And the government significantly tightened environmental standards and launched crackdowns on polluting farms that flaunted waste-management rules.

Those regulatory pressures may have incentivised cash-strapped farmers to seek funding from the carbon markets for upgrades already encouraged by the state, Gale said.

At the same time, many breeders faced significant upfront costs from the construction of huge facilities. Many operated at a loss as they rebuilt herds. Soon afterward, the market over-corrected: farmers bred too many pigs, creating a supply glut that tanked prices and compounded cost pressures – a problem that has continued until today.

“It’s not clear that pig farms in China would have been able to scrape together the cash to build these projects – at that time, in that economic context – if it wasn’t for their ability to get offsets,” said Even Pay, a director at research firm Trivium China who reviewed CarbonPlan’s research.

While effective waste-management projects can pay for themselves over time – even without credits – Pay said it was possible that some Chinese pig breeders operating under extreme price volatility needed the additional incentive of credit revenue to adopt emissions-curbing practices.

China’s agricultural sector still lags behind energy and heavy industry when it comes to access to the financial, technical and policy support needed to prioritise emissions cuts, Pay said: “The sooner that a wide range of funding tools are available, the better.”

Christian Shepherd