EY US has formed an alliance with climate software provider Watershed to help companies measure, report and cut greenhouse gas emissions across their full value chain — scopes 1, 2 and 3.

The pairing matches Watershed's AI-powered sustainability platform with EY US advisory, implementation and program management muscle. The stated deliverables: enterprise GHG measurement, product carbon footprinting, and sustainability data management aimed at decarbonization programs.

For practitioners, the pitch is an end-to-end toolkit spanning data collection, measurement, reporting, product-level footprinting, planning and advisory services. The companies flagged the complexity of scope 1, 2 and 3 methodologies as the problem they're solving — the scope 3 piece alone, covering supply chain emissions, is routinely the hardest number in any corporate inventory to pin down.

Who is Watershed?

Founded in 2019, Watershed built its business on an enterprise sustainability platform for measuring, reporting and reducing emissions. The stack includes:

• A climate database for granular emissions measurement
• Software for sustainability reporting and supply chain engagement
• A marketplace for carbon removal and clean power projects

The company has since widened its coverage to waste, water, land-use change, and social and governance metrics.

Why now?

Timing is the story. The alliance lands as new disclosure regimes move from draft to deadline, including California's SB 253 in the U.S. and Europe's CSRD. Both put scope 3 reporting obligations on companies that, in many cases, have never produced an audited emissions inventory.

Watershed CEO Christian Anderson framed the move as more than compliance plumbing:

"Over the next few years, sustainability work is going to evolve. It will become more automated and action-oriented. Sustainability insights will fuel operational efficiency and resilience in addition to meeting reporting demands."

That's a signal worth tracking: the accounting-first phase of corporate climate work is shifting toward automation, and vendors are positioning accordingly.

Derek Przybylo, who leads the EY-Watershed Alliance at EY US, said:

"By combining EY US sustainability advisory, implementation and program management capabilities with Watershed's sustainability AI platform, the EY-Watershed Alliance helps clients strengthen emissions measurement, automate reporting and build scalable sustainability solutions that support their decarbonization initiatives and regulatory readiness."

What does this change for the market?

Big Four advisory firms pairing with specialist software vendors is becoming the standard template for emissions reporting: the firm brings the audit trail and change management, the platform brings the data engine. EY US picking Watershed gives the 2019-founded company a major channel into large corporate clients facing first-time disclosure obligations.

What happens next depends on the regulators, not the partners. Watch the implementation calendar for California's SB 253 and the CSRD's requirements for non-EU companies — the first filing deadlines will decide how fast this market consolidates.