Podcast: Sustainability Defined by Scott Breen & Jay Siegel

What does sustainability actually mean, not as a buzzword, not as a corporate talking point, but as a real, working concept that shows up in daily decisions?

That's the question Sustainability Defined has been wrestling with since 2017, and the answer, it turns out, is more interesting than you'd expect.

Founded and originally hosted by Scott Breen and Jay Siegel, two sustainability professionals with backgrounds in business and environmental consulting, the podcast started with a simple and genuinely useful premise: ask one guest per episode to define sustainability in their own words, then build a conversation around that definition. The show has since passed to new hosts Nethra Rajendran, a sustainability strategist with experience across corporate and nonprofit sectors, and Cecilia Rios, a circular economy and sustainable design practitioner. Together they continue the format Breen and Siegel established, carrying forward a catalogue that has accumulated perspectives from hundreds of practitioners, scientists, entrepreneurs, and advocates, each adding a slightly different lens to a concept most people assume they already understand.

What the Podcast Actually Is

Sustainability Defined operates in interview format, with each episode centered on a single guest and their work. Topics range widely: regenerative agriculture, circular economy models, sustainable fashion, corporate ESG strategy, environmental justice, clean tech, and urban design, among others. The connective tissue across all of it is the opening definitional question, which sounds simple but consistently surfaces something worth thinking about.

Breen and Siegel built the show with a practitioner's sensibility. Conversations are grounded, specific, and low on abstraction. Guests aren't asked to predict the future or deliver hot takes. They're asked to explain what they actually do and why it matters. For a topic as broad and frequently vague as sustainability, that editorial discipline is rarer than it should be and more valuable than it sounds.

The production is clean, the pacing is relaxed, and episodes typically run between 45 and 75 minutes, long enough to go somewhere real without overstaying their welcome.

Why It Works for ClimateInvested.org Readers

The Climate Invested audience is solutions-oriented and already past the basics. They don't need another episode explaining why climate change is real. What they need is exposure to the people and ideas at the edges of what's possible, the practitioners building new systems rather than just critiquing old ones.

Sustainability Defined delivers that consistently. More and more professionals working at the intersection of business and environment are turning to long-form podcast content as a way to stay current across sectors they don't work in directly. This show covers that ground well, making it genuinely useful for readers who want to understand how sustainability shows up across industries, not just in the obvious places.

The definitional framing also has a quiet educational value. Hearing how different practitioners define the same term builds a more flexible and sophisticated understanding of the concept than any single article or textbook could.

One Honest Note

The show has changed hands. Scott Breen and Jay Siegel, who built the podcast and hosted it through more than 200 episodes, have passed it on to new hosts Nethra Rajendran and Cecilia Rios. For longtime listeners, the transition is noticeable. The original run had a particular chemistry between Breen and Siegel, two people with genuine rapport and shared professional context, that gave even dry topics a conversational warmth. The new version is competent and well-intentioned, but it is a different show in feel if not in format. New listeners coming in fresh may not notice the difference. Those who start with the back catalogue and then move forward likely will. Neither era is without merit, but it is worth knowing the show you are subscribing to today is not exactly the one that built the reputation.

The Bottom Line

Sustainability Defined is one of the more quietly reliable resources in the sustainability podcast space. It won't give you headlines or outrage. It will give you a steady, well-curated stream of people doing real work and explaining it clearly. For anyone trying to build a deeper working vocabulary around sustainability across sectors, it is hard to beat.

🔗 Listen on Spotify / Apple Podcasts.

Who It's Best For: Professionals and curious learners who want broad exposure to sustainability across industries. Strong pick for anyone working in or considering a career in ESG, clean tech, circular economy, or environmental consulting. Also valuable for readers who want to understand how sustainability is being defined and practiced beyond the climate conversation specifically.

Episodes: 200+

Episode Length: 45 to 75 minutes

Best Listened To: By topic or guest, the back catalogue rewards searching rather than linear listening