The hardest part of climate reporting isn’t tracking what you control, it’s figuring out what you don’t. That’s why Scope 3 emissions deserve your attention; it’s where the majority of emissions live, and where regulators and customers are now pointing their spotlight. According to consulting giant McKinsey, Scope 3 emissions often make up around 90% of a company’s total carbon footprint. That means the carbon math isn’t complete until your supply chain is in the conversation.
And here’s the kicker: while you can report Scope 3 using financial data alone—and that’s completely acceptable—customers increasingly expect more. They want to know exactly how many emissions their product or service generates, and to get that level of detail, you need activity data from your suppliers. They hold the information that determines whether your reporting is truly credible.
Engagement is no longer optional. Businesses that sell to other companies are being pulled into Scope 3 reporting, whether they want to be or not. The only real question is how quickly you’ll get ready.
Why Supply Chain Engagement Is Rising Now
The timing isn’t random. We’ve hit a turning point where laws, global frameworks, and market pressure are converging.
California’s Climate Disclosure Laws
California has long been a leader in environmental regulation in the U.S., setting the standard that other states follow. In 2023, California passed Senate Bills 253 and 261, which require thousands of companies, many headquartered outside the state, to report their Scope 1, 2, and 3 emissions.
The rules apply to businesses with more than $1 billion in annual revenues operating in California, which covers a wide swath of national and international players. These laws don’t just raise the bar in California; they send a message that the U.S. is catching up with global disclosure norms.
Global Momentum
The EU Corporate Sustainability Reporting Directive (CSRD) goes even further, mandating detailed emissions disclosures for about 50,000 companies. This includes many based outside Europe that do business within its borders. Similar requirements are gaining traction in the UK, Canada, and Japan. When your customers are complying with multiple jurisdictions, the expectation for accurate supplier data multiplies.
Market Pressure from Large Corporations
Even without regulation, companies are moving. More than 70% of S&P 500 firms report Scope 3 data. Multinationals such as Amazon, Microsoft, and Hewlett-Packard are already requiring suppliers to submit emissions information as part of standard procurement. For smaller B2B companies, the message is clear: either provide credible data or risk being left out of the supply chain.
If the policy landscape explains the “why,” the next step is to unpack how supply chain engagement actually works.
What Supply Chain Engagement Looks Like
Engaging your supply chain isn’t a one-and-done request for data; it’s an ongoing process that blends expectation-setting, standardized reporting, and genuine collaboration. Companies that treat it as a compliance exercise fall behind, while those that build it into relationships see stronger results.
Setting Clear Expectations
The first step is transparency. Suppliers need to know what you expect, why it matters, and how the information will be used. Many companies create supplier codes of conduct or integrate climate criteria into procurement contracts. Communicating both the “why” (regulation, customer pressure) and the “what” (emissions data) builds buy-in.
For example, Walmart’s Project Gigaton enlisted over 5,900 suppliers to commit to reducing emissions in line with its own climate targets. This buy-in helped the company achieve its goal of reducing, avoiding, or sequestering 1 billion metric tons of greenhouse gas emissions by 2024, 6 years before its 2030 target.
Data Collection and Standardization
Collecting supplier data is notoriously messy without standard frameworks. Aligning data collection with established frameworks like the GHG Protocol or the CDP Supply Chain Program offers consistent methods that make data comparable across industries. Fortune 500 companies increasingly require suppliers to disclose emissions using these systems, avoiding mismatched spreadsheets and unverifiable estimates.
Partnering for Reductions
But engagement doesn’t stop at reporting. For example, Unilever’s Supplier Climate Program partners with suppliers to provide hands-on guidance and tools to help them reduce emissions within their operations. Smaller suppliers often lack the resources to act independently, so large companies provide training or phased approaches that make participation possible. Over time, collaboration builds stronger relationships and shared progress toward climate goals.
What It Means for B2B Companies
If you sell to companies with disclosure obligations, you’re already in scope. Customers will be asking for your emissions data, and not responding could mean strained relationships or lost contracts. In fact, a recent survey by EcoVadis and the Stanford Graduate School of Business found that more than 50% of global corporate buyers increased spending with sustainable suppliers in 2025—and nearly the same percentage plan to end relationships with unsustainable vendors within the next two years.
On the flip side, suppliers that can deliver reliable Scope 3 data position themselves as trusted, future-ready partners.
In a crowded market, transparency is becoming a competitive advantage. Proactively gathering and sharing emissions data signals that you’re not just keeping up, you’re leaning forward. That builds trust, strengthens your business case, and reduces the scramble when disclosure requests arrive in your inbox.
How Emerald Supports Supply Chain Engagement
At Emerald, a sustainability consultant to organizations across industries, we help companies develop and improve their greenhouse gas emissions reporting. This includes designing supply chain engagement strategies and building communications frameworks and templates that make it easier for procurement teams to request and collect data. We support suppliers on the receiving end too, offering training and resources that help them meet requirements without overwhelming their capacity.
Most importantly, we integrate Scope 3 engagement into broader sustainability roadmaps so that it’s not a one-off project. Embedding this work into long-term planning avoids fatigue and helps ensure companies can show progress year over year. As we’ve seen with our clients, successful engagement is as much about relationship-building as it is about numbers on a spreadsheet.
The Bottom Line
Supply chain engagement is now the foundation of Scope 3 reporting. California’s new laws and Europe’s CSRD make clear where the world is heading, and the ripple effects will reach every B2B company, regardless of size. Companies that wait risk being left behind. Companies that move early can strengthen customer relationships and find real opportunities for emissions reduction.
At Emerald Built Environments, A Crete United Company, we are sustainability consultants and a trusted partner who helps businesses prepare for this future with strategies that combine compliance, collaboration, and competitive advantage. If you’re ready to turn Scope 3 reporting from a headache into a launchpad, let’s talk.
