Tangelic Talks – Episode 03
How Much Growth is Too Much? Dr. Tom Murphy Shares Insights on Balancing Innovation, Equity, and Planetary Limits at Tangelic Talks
5.3 minutes to read
In this thought-provoking episode of Tangelic Talks, we sit down with physicist and sustainability expert Tom Murphy to explore the tension between our pursuit of endless growth and the urgent need to live within our planet’s finite boundaries. Drawing from his expertise in energy systems and his keen insights into humanity’s ecological overshoot, Tom challenges us to rethink our love for modern conveniences and the materialistic culture that fuels climate change.
The Problem with Modernity
Dr. Murphy describes modernity as a period marked by rapid increases in energy use, resource consumption, and economic growth. While these advancements have improved quality of life for many, they’ve also created a distorted perception of sustainability. “Modernity is like a stunt,” Dr. Murphy argues. “It’s not ecologically rooted and cannot last indefinitely.”
One striking statistic he shares is that 96% of the planet’s mammal biomass is now composed of humans and their livestock, leaving only 4% for wild mammals. “We’re initiating the sixth mass extinction,” he warns, urging a reevaluation of humanity’s role as stewards of the planet.
The Cultural Challenge
Beyond technological fixes, Dr. Murphy emphasizes the need for a cultural shift. He critiques the anthropocentric worldview that positions humans as separate from and superior to nature. Instead, he advocates for a mindset rooted in humility and interconnectedness. “If we viewed rivers and forests as living entities rather than resources, we’d treat them very differently,” he explains.
This cultural shift requires challenging deeply ingrained assumptions about consumption and growth. Dr. Murphy compares modernity’s relentless expansion to a cancer, unsustainably consuming the Earth’s resources at the expense of ecological health.
Understanding Overshoot
Central to Dr. Murphy’s argument is the concept of overshoot, which occurs when humanity exceeds the planet’s carrying capacity. “We’re burning through finite resources and pushing ecological systems beyond their limits,” he says. Examples include deforestation, overfishing, and reliance on fossil fuels. These behaviors create a temporary illusion of abundance but lead to long-term instability.
Steps Toward Sustainability
For individuals, Dr. Murphy suggests a profound rethinking of priorities. “Fall out of love with modernity,” he advises. This means shifting away from materialistic pursuits and reconnecting with the natural world. Practical steps include:
Redefining Success: Prioritize community, well-being, and ecological health over economic growth.
Living Simply: Reduce reliance on non-renewable resources and adopt sustainable practices.
Advocating for Change: Support policies and initiatives that align with planetary boundaries.
Dr. Murphy also stresses the importance of embracing cultural narratives that honor the Earth’s ecosystems. “We’re not separate from nature,” he reminds us. “Our survival depends on living in harmony with it.”

Thought Provoking Q&A Session with Tom Murphy
I think it's incredibly hard. I don't expect to get very far on that actually. And I think that it's going to change one death at a time. I mean, that's a crude way to say it, but, maybe the better way to say it is one birth at a time because every child that's born into this world forms a mental construct of what this world is and what's important based on what they see. Partly based on what the elders tell them, but we all know that adolescents disregard anything that the elders say.
So I think that a child born in the year 2200 is going to see a completely different world and is going to just get on with things as they are. Humans are very adaptable and plastic as a species. As an individual, we are not quite so plastic. And so I don't think that you're going to really change culturally the attitudes by changing the individuals. I mean, it can happen, but it's not the main mechanism, it is just going to be replacement with new generations and hopefully new approaches.
Sure, and in my mind, it is completely the wrong approach because it doesn't even question that the technological world is what we should be doing. But that's exactly what got us here. As a physicist, you know, I started approaching the energy questions with the usual kind of quantitative assessments and found that 10,000 times as much sun hits our planet as what we use in our industrial society. And so, shouldn't that just be the end of story? I mean, we should obviously be using solar. And I was an enthusiast. And being a hands on kind of experimentalist, I built my own solar power system and battery system and experimented with different ways of doing it, different chemistries, batteries and learned the ropes.
And I learned a lot of things, including how difficult it really is to deal with an intermittent energy supply like the sun. But what really startled me eventually was when I saw a study by the Department of Energy looking at electricity production. And if you produce electricity from natural gas or coal versus solar or wind, the materials demand is something like an order of magnitude higher for the solar and wind. And it's because it's a diffuse source that requires a lot of stuff to scoop it up and convert it and store it and all this. And so it would actually accelerate our damage to the living world. And if you look at what has caused this,sixth mass extinction initiation, it's not greenhouse gases, its habitat loss, its deforestation, its solutions from manufacturing, it's mining, it's fragmentation of habitats, it's interactions with our infrastructure, you know, roadkill and bird strikes on windows.
This nosedive is only made worse by greenhouse gases. I mean, that's very clear. But if you could just eliminate greenhouse gases today in a blink, we're really not out of the woods. We are not even stabilized. We are continuing. In fact, we might even speed it up because of the heavy materials demand to convert our infrastructure. Convert the Titanic into a different power system.
There aren't many examples, certainly not of things that happen very quickly. It tends to be that people are forced into big changes because they have no choice. And that can happen quickly. You know, if a volcano goes off and your town is destroyed, the people who survive are going to pick up a different lifestyle. You know, they have no choice.
And this change in the way a society lives is not usually an individual on a five year time scale. That's, you know, a much slower process. But I will say that the cultures that are able to last a long time are the ones that are sustainable by definition.
So for example, there's a lot of indigenous cultures that deliberately thought about long term sustainability and had very deliberate rules in place that are not at all accidental of things like the honest harvest where you take only what you need. You take no more than half. You don't take the first one that you come across because what if it's the only one? So a lot of restraint. Wisdom and restraint are words that go together. There's a lot of restraint in the Northwest where I live. The natives really lived on salmon. I mean, salmon, that was their lifeblood. And they knew this, obviously. And each year the salmon would return. And you can imagine, you've been waiting, maybe a little hungry. You've eaten through all your stores and it's going bad or whatever. And so you're really eager for this.
But what do they do? What they do is they watch for four days as the salmon go upstream and they have a celebration. And only after four days have passed do they start fishing. That's restraint.
And there's obviously a good reason for it. You're only going to have salmon next year, next year, next year, next year if you let them have their cycle.
Well, so that's a great question, because being an astrophysicist, billions of years doesn't faze me. And the human genus has been around for three million years and our species 300,000 years and anatomically modern humans for hundred and fifty thousand years. And when we're dealing with ecological questions that are subject to evolutionary forces in a relationship with other beings in the community of life, then we're dealing with time scales that are at least many tens of thousands of years. So anything faster than that is too fast for the community of life to keep pace.
And because we're deeply integrated into a community of life, whether we know it or not, we've forgotten that. We're going to learn that that's true. You know, you have to be careful not to introduce radical innovations that are too fast for the community to keep up with. Agriculture is one of those things that is only 10,000 years old and way too fast for the living world to equilibrate to that.
And so when I think of sustainable, I start at 10,000 years, but, you know, a hundred thousand is maybe more appropriate for a species level in terms of evolutionary ecology. That's an ecologically relevant time scale.
I came across this story in the book called Braiding Sweetgrass by Robin Wall Kimmerer, and I think in Minnesota or somewhere like that, there were some natives who were gathering wild rice in canoes on little ponds and lakes. They would shake the rice into the canoe and a lot would fall into the water. And this European went along with them and said, I could design something to help you get 90- 95% of the rice because right now you're only catching about 50% of the rice. And they're like, huh? Like what? Why the hell would we want to do that? Because what are the ducks going to eat? Why would the ducks come here? How is it going to reseed itself? This is not all for us. And so that's the attitude. It's not all for us. And our culture is, of course, it's all for us.
Tom Murphy
Professor in the physics department at UCSD, Associate Director of CASS, the Center for Astrophysics and Space Sciences, and co founder of Planetary Limits Academic Network.

Tom Murphy is a professor emeritus of the departments of Physics and Astronomy & Astrophysics at the University of California, San Diego. An amateur astronomer in high school, physics major at Georgia Tech, and PhD student in physics at Caltech, Murphy spent decades reveling in the study of astrophysics.
Murphy’s keen interest in energy topics began with his teaching a course on energy and the environment for non-science majors at UCSD. Motivated by the unprecedented challenges we face, he applied his instrumentation skills to exploring alternative energy and associated measurement schemes. Following his natural instincts to educate, Murphy is eager to get people thinking about the quantitatively convincing case that our pursuit of an ever-bigger scale of life faces gigantic challenges and carries significant risks.