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

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.” 

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…