I’ve found a surefire way to mess with the good vibes during my on-the-record conversations with CEOs and senior executives: bring up carbon accounting. In an instant, a conversation that felt open and transparent moments prior can turn into guarded talking points or simply go quiet.

Carbon accounting may be the wonkiest topic in the already wonky world of climate change and emissions reduction. And few areas inspire more passionate debate and infighting than the rules for measuring and attributing them. But underneath the jargon lies a high-stakes question: who is responsible for each ton of carbon emissions? How that question is answered over the coming months and years will shape everything from climate regulations to corporate energy purchasing decisions.

A report by the Aspen Institute and shared exclusively with me ahead of its Oct. 9 release offers a rare window into that fight. It draws on a multi-day summit this February that brought together the field’s key players—including academics, NGOs, and industry voices—to debate the path forward on how best to account for carbon emissions. I attended the closed-door summit having agreed to report on the discussion without identifying individual participants. It concluded in a ceasefire of sorts with promises to work together even as the core debates remain unresolved.

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To understand the carbon accounting landscape, you need to understand the system at the center of the debate. For more than two decades, one approach, known as the Greenhouse Gas Protocol (GHGP), has flourished and become the de facto global standard. Under GHGP’s approach, emissions are divided into scopes: Scope 1 for direct emissions from a company’s operations, Scope 2 from a company’s purchased electricity, heat, and cooling, and Scope 3 for value chain emissions. The GHGP approach has driven a variety of guidance documents and informed regulation and certifications issued by other entities.

But, as with any such initiative, GHGP is not perfect. And a growing number of stakeholders—particularly businesses—have called for changes of varying scope and scale.

The resulting fault lines in the carbon accounting debate are many. There are technical questions like over what time scale (hourly vs. annual) companies must match their electricity use with their clean energy purchases. And there are questions about the degree to which carbon accounting relies on estimates rather than true measurements. But, perhaps more than anything else, there is a debate about responsibility: in accounting for emissions, who should really be held responsible?

The technical matters are divisive on their own. The philosophical questions cut to the core of the climate challenge.

The weather in Aspen was unseasonably warm. That didn’t keep the seminar room from turning chilly at times. While no one in Aspen said that the GHGP approach is perfect, perspectives on what to change and by how much varied widely.

Defenders of the current system say that Scope 2 and Scope 3 reporting has motivated voluntary corporate action. Scope 2 rules, in particular, give companies a clear way to claim credit for the clean electricity they buy, and that predictability has helped fuel a boom in long-term renewable power contracts, known as power purchase agreements. And predictability matters. While in theory it may be possible to design a better system, the GHGP approach is entrenched, and it could take decades for a new system to earn such widespread adoption.

The critiques are multifold. The GHGP approach allows for “double-counting.”In other words, multiple companies end up accounting for the same emissions under different scopes. Think of steel in a building. The steel producer, the construction firm, and the building owner are all technically responsible for the steel emissions.

A primary alternative approach, which originated in academia and now has a coalition of industry players advocating for it, accounts for emissions using “e-ledgers.”Every unit of emissions is accounted for once, placed on a ledger, and then transferred as a product moves through the world. It’s an elegant approach with real advantages. It would incentivize companies to focus on decarbonizing their own operations and give them high-quality emissions data to use in procurement. But some in the room in Aspen noted that it would be difficult to implement. It only really works if every single player on the value chain participates.

The sharpest divide, however, concerns emissions from using a product. Under GHGP’s Scope 3, an oil company counts the emissions from every gallon of gasoline its customers burn. That is the primary driver of its enormous carbon footprint. An e-ledger works differently, with emissions traveling with a product and responsibility belonging to whoever does the burning. That leaves consumers with greater accountability even if they have little influence over the broader system.

The e-ledger approach emerged from the corners of academia in a series of highly publicized articles beginning in 2021. And, in 2025, a coalition of companies including ExxonMobil, BlackRock, and others backed the launch of a business coalition to advocate for an e-ledger approach.

At the same time, the call for change comes amid the retrenchment of climate from its front and center position in the public zeitgeist, making some companies less willing to commit the resources necessary to fully embrace the work required by GHGP. GHGP has responded, hiring a new CEO and instituting a string of reforms.

Given the stakes and the players involved, it’s no surprise that the conversations in Aspen were heated at times. And yet the summit ended with a detente of sorts, as participants agreed to work together to find common ground. Indeed, some participants noted that e-ledgers can help with tracking a product’s carbon footprint, while the broader GHGP rules should apply for a whole company.

What happens next in this wonky corner of the climate community concerns more people than you might expect. It will shape regulations—including climate disclosure rules in California and the European Union—and affect where businesses target their climate initiatives. Perhaps most importantly, it will affect how we answer the question of who is responsible for future emissions.