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Behind the world’s first ‘zero-carbon’ arena, a questionable carbon credit market

Climate Pledge Arena in Seattle is as green as buildings get, but doubts about some Colombian rainforest carbon credits used to offset its construction highlight how challenging it is to zero out emissions.
The Climate Pledge Arena  in Seattle, Wash. on Oct. 19, 2023.
Climate Pledge Arena in Seattle on Oct. 19. Steph Chambers / Getty Images

SEATTLE — At Climate Pledge Arena, the ice is made from rainwater, the Zambonis are electric and the roof is essentially recycled, dating back to a previous version of the venue erected in 1962. 

From the solar panels on the parking garage to the free public transit to attend the games, the building’s operators have chosen green at every turn, leading to an announcement in October that it was the world’s first “zero-carbon” certified arena.

It’s a title that some carbon experts say is tough to prove. 

The 18,300-seat arena produces few direct emissions from its operations, but to make up for the greenhouse gasses produced during its construction, Seattle-based Amazon purchased voluntary offset carbon credits that originate in the Colombian rainforest. The marketplace for voluntary offsets has been roiled by scientific findings that suggest that many carbon projects, particularly those designed to prevent deforestation, routinely overstate their impact.

“Do we see limitations in the legacy carbon market? The answer is yes,” said Jamey Mulligan, head of carbon neutralization science and strategy at Amazon, adding that the company was using its scale to improve the market. 

In an interview, Mulligan said the company purchased the credits several years ago, when the company was just getting started in the carbon marketplace. He said Amazon believed this particular project used relatively conservative estimates and was high quality, but also acknowledged that the voluntary carbon marketplace needed more rigor. 

Mulligan said more “work is needed” to ensure that baseline projections are conservative and methodologies are sound in nature-based carbon credit projects overall. 

“This is a market that has to succeed, and it has to scale well beyond where it’s been operating today,” he said. “And it won’t get there without trust.”

Donna Lee, an executive at the carbon rating company Calyx Global, said her firm’s analysis suggests that the rainforest credits purchased for the arena have likely helped prevent some deforestation. But Lee also said it was at “risk of overcrediting,” meaning that the project was likely claiming more benefits than it delivered, according to the Calyx analysis. 

That the folks at Climate Pledge Arena, backed by Amazon’s deep pockets and long bench of sustainability workers, can’t convince outside experts that their offsets live up to their billing on paper shows how deep the crisis of credibility in the voluntary carbon market has become. 

If Climate Pledge Arena is a monument to the possibilities of a green future, it’s also a prime example of how challenging it can be to achieve true carbon zero.

“They’ve made some good faith efforts here, but like a lot of companies, they’re kind of trapped in this evolving landscape of what’s considered credible,” said Derik Broekhoff, a senior scientist at the Stockholm Environment Institute in Seattle, of the arena operators. “It’s hard to work within a system that’s full of flaws.” 

Credit crunch

Carbon credits, or offsets, are emissions removals or reductions. Companies buy these credits, which are typically listed in nonprofit registries, and use them to balance out carbon pollution associated with their business. 

Companies have used voluntary offsets to market products with labels like “carbon neutral,” to meet internal emissions goals and to support climate action projects. Critics say they can facilitate greenwashing and can limit companies’ ambitions to reduce emissions in core business practices. 

Building operations make up about 27% of worldwide carbon emissions, according to Architecture 2030. Common building materials, like cement, iron, steel and aluminum, are responsible for an additional 15%. 

Broekhoff discourages companies from relying on offsets to make marketing claims — “many of these credits may be associated with hot air,” he said. Meanwhile, others, including Amazon, are trying to overhaul the voluntary carbon marketplace, where prices have cratered, and make it more rigorous.

Climate Pledge Arena is about as green as buildings get. The International Living Future Initiative (ILFI), which evaluated the arena’s emissions data and deemed it a “zero-carbon” building this fall, requires operators to remove all fossil fuels, operate efficiently and use low-carbon materials in construction. 

Beyond the requirements for the zero-carbon label, the arena’s sustainability team collects invoices from food vendors, waste haulers, utilities and performers to estimate the indirect emissions of every concert and sports event. In the first year of operations, the building was responsible for about 38,000 metric tons of CO2-equivalent emissions. The arena operators have promised to purchase offsets each year to counterbalance all indirect emissions, meaning the carbon cost of each guest’s concert T-shirt, hamburger and Uber ride is accounted for. 

Amazon money, Colombian credits

The arena purchased renewable energy certificates to account for all of its power needs, and it plans to be an anchor user of the local electric utility’s plan to create a new renewable energy facility. 

But an arena’s construction can only be so green. It tallied about 37,000 metric tons of CO2 equivalent while being built, according to Rob Johnson, the senior vice president of sustainability and transportation for Climate Pledge Arena and the Seattle Kraken, the NHL team that plays there.

ILFI allows operators to buy carbon offsets once to counterbalance emissions from construction. As part of its naming agreement, Amazon took the lead on acquiring offsets. 

The company purchased and retired carbon credits from a project in Colombia called Acapa, which is part of the nonprofit Verra registry, an organization that sets standards for carbon market projects. When asked, Amazon did not share the price it paid for Acapa credits. 

The nearly 144,000-acre Acapa project was initially founded by the United States Agency for International Development and then handed off to a series of nonprofits. The project aims to reduce logging by local families and to incentivize other economic projects with less environmental impact like growing coconuts, acai and cacao, according to project documents.

Carbon credits of this type, called REDD (Reducing Emissions from Deforestation and Forest Degradation), have come under scrutiny from academics and journalists. 

Several academic studies have found these types of credits, on aggregate, offer a fraction of their claimed benefit. A Guardian headline called these credits “worthless.” 

In general, “the methodologies are not science-aligned,” said Barbara Haya, the director of the Berkeley Carbon Trading Project, who has argued that registries are so flexible that they allow project developers to overestimate benefits without sufficient independent auditing.

Lauren Withey, who now works for the nonprofit Earthjustice, spent about two years in Colombia studying nature-based offsets like Acapa. She said it’s easier to design a project that creates carbon credits on paper than it is to change the economics of how poor villages in remote rainforests operate. 

“Fundamentally, it’s just very hard to change livelihood dynamics in these communities,” Withey said. 

Meanwhile, several upstart carbon rating agencies now offer independent modeling of carbon projects, which rely on satellite and project data. 

Lee, of the rating agency Calyx Global, said her firm believed the Acapa project had delivered some emissions reductions.

“It really has reduced deforestation. We can’t say that of every project,” Lee said of her company’s assessment. “However, they are overcrediting. It’s really common.” 

Penance, not absolution

The Verra registry, which has been the focus of scrutiny, on Monday revised its methodology in an attempt to provide better quality control. The nonprofit will now set project baselines instead of project designers and will use remote-sensing technologies to ensure emissions reductions. 

“It will start bringing more dependable results to REDD and enhance confidence and trust,” said Toby Janson-Smith, Verra’s chief program development and innovation officer, in a news conference.

Johnson, of Climate Pledge Arena, said his team relied on Amazon’s carbon market expertise for offset purchases. 

Amazon is now the largest purchaser of renewable energy in the world, Mulligan said. It’s also the largest buyer of direct air capture credits in the world. The company co-founded the Leaf Coalition, which is financing large-scale tropical forest protection and is attempting to set a stricter standard for offsets and transparency. 

When asked if he felt it was fair to call the arena a zero-carbon building, given the uncertainty swirling around REDD projects, Mulligan said: “That’s an interesting philosophical question that we probably won’t weigh in on,” adding that the arena and Amazon had done “hard work to decarbonize the actual facility and its operations and value chain” before buying the offsets. 

Haya agreed that the upfront work to make the building as efficient as possible and create new sources of renewable energy was critical. 

“The most important thing is reducing their own direct emissions and that’s how they should primarily be judged,” Haya said. 

Some think the voluntary carbon marketplace has lost so much credibility that it’s time to ditch marketing products as “carbon zero” or “net zero” when carbon credits are involved. 

“It’s a risk to convey you’re somewhere equivalent to zero,” Broekhoff said. “View these carbon credits as penance, not absolution.”