Senior Sustainability Leadership Has Never Mattered More. Most Businesses Still Can't Access It.
The conversation about the future of sustainability leadership is often happening within large corporations. Here’s what it looks like across small and mid-sized businesses and the broader market.
April 29, 2026
A question has been circulating in sustainability community recently, whether the Chief Sustainability Officer (CSO) role is still fit for purpose or whether it needs to evolve into something different.
It's a legitimate discussion. For large, sophisticated organizations that have spent a decade or more embedding sustainability into their operations, leadership and accountability structures, disclosures, and long-term strategy, the question of how the function should be led, and by whom, is genuinely worth asking.
But there's something important missing: asking whether companies are large enough, advanced enough, and well-resourced enough to have a sustainability function in the first place. For the vast majority of businesses navigating sustainability right now, the question isn’t whether to restructure leadership. It’s more fundamental...how to access the right level of leadership to move the work forward.
Beyond supply and demand, the real staffing problem is access.
The sustainability talent market has undergone a step-change in demand, with job postings for internal sustainability roles surging across all seniority levels, while senior-most roles remain more limited in number (Deloitte). And while traditional hiring remains the right answer for many organizations, the full-time model isn't always accessible or the right fit for a company’s current sustainability maturity level.
The result is a talent market with a significant and growing gap at its center. At one end, a relatively small number of larger companies with mature sustainability functions and the budget to attract experienced leadership. At the other end, a vast segment of small and mid-sized businesses, growth-stage businesses, and PE-backed companies, many of which are just beginning to engage seriously with sustainability. These businesses need the same quality of strategic sustainability expertise but simply are not prepared to resource it with a full-time senior hire.
"For the vast majority of businesses navigating sustainability right now, the question isn’t whether to restructure leadership. It’s how to access the right level of leadership to move the work forward.”
A Different Kind of Problem
It's worth being specific about what this gap actually looks like, because it's easy to underestimate from the outside.
For most businesses, when facing a sustainability challenge, the question becomes how to best access the expertise needed to solve the problem.
Take for example, a mid-market manufacturer facing supply chain sustainability requirements from a major customer. They don’t need the cost burden of a C-level sustainability executive for what may be a fairly straightforward strategy. They need an experienced leader who understands Scope 3 emissions, can build a supplier questionnaire framework, knows how to talk to procurement teams, and can give leadership and the board a clear, honest view of where they stand and what needs to be done. They need that person reliably, on a defined timeline, and at a cost that works for a business that has never had a sustainability function before.
A PE-backed business approaching an exit needs credible environmental, social, and governance data that demonstrates operational efficiencies or value creation, a coherent sustainability narrative for potential buyers or fund managers, and someone who can stand behind it through due diligence. They need all of this on an accelerated timeline, and likely for the duration of the exit process — not as a permanent hire.
A growth-stage consumer brand that has discovered it has serious sustainability obligations needs someone who has done this before, can start immediately, and will remain accountable for the outcomes three months from now.
These businesses are not edge cases. They are the majority of the market. And for all of them, the question is the same: how do we access the right expertise, in the right form, at the right time?
What the Fractional Model Actually Does
A Fractional Sustainability Leader (FSL) is not a cheaper substitute for a CSO. That framing misunderstands both roles.
An FSL is a senior sustainability leader, someone who has experience within the corporate setting leading the function at director, vice president, or C-suite level. They know how to work across multiple organizations simultaneously and are embedded as a genuine senior member of the organization. Their role goes beyond typical consulting or advisory support. They are not just delivering reports or offering recommendations—they are helping lead the work. They play a key role in driving sustainability forward alongside senior leadership. They may attend leadership meetings. They may brief the board. They own the outcomes.
There is a risk worth framing for employers regarding resourcing: when sustainability roles are filled with less experienced professionals, the function can lose strategic influence at precisely the moment it needs more of it. An FSL can help address this directly, working alongside a junior sustainability professional or internal resource to provide the senior strategic direction that makes their work more effective and more credible internally. The expertise is in the room. The internal resource has someone to work with, not just a brief to execute.
What the fractional model does is make senior sustainability leadership accessible to organizations that are at an earlier stage of the journey. Businesses that need the expertise, accountability, and strategic thinking of an experienced leader, but don't yet need it full-time or can't resource it that way.
This is not a downgrade from full-time leadership. It's a different deployment model for the same level of expertise. And it serves a part of the market that the traditional hiring model has largely left behind.
The Work That Actually Matters
In the end, what most businesses need from sustainability leadership is the same thing, regardless of how it's structured: an experienced leader who understands the landscape, can make a credible business case internally, knows how to build and implement a program that holds up under scrutiny, and is accountable for outcomes.
That expertise should be prioritized, connected into senior leadership, and empowered to get things done. The fractional model is our attempt to extend experienced sustainability leadership to the businesses that need support doing the practical, step-by-step work of building sustainability capability within their organization. This applies to a wide range of businesses today.
The conversation about leadership structures matters. But the most important conversation, and the one we think about every day, is simpler: how do we get more businesses doing this work, with the right level of expertise behind it, starting now?
That's the gap we exist to close and the fractional sustainability leader model is designed to fill.
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FSL Collective is the professional home for fractional sustainability leaders. If you're a company looking for senior sustainability expertise — or a sustainability leader considering the fractional path — we'd welcome the conversation. Visit fslcollective.com or reach out at info@fslcollective.com.
