I remember the moment when I understood that humanity could destroy itself, not in the blinding flash of nuclear explosions, but by the gradual, almost invisible, buildup of our own waste products, our various forms of pollution.
I was in junior high, sometime in the 1967-68 school year, in 7th grade science class. We were learning about the interactions of plants and animals in the biosphere, and discussing the difficulties of setting up a science fair-type demonstration in a sealed aquarium. It's hard to fit in enough plant biomass to balance the oxygen use of even one fish; but even once you do that it can't be self-sustaining on the kind of scale we could possibly achieve. Eventually the fish would suffocate in its own waste.
Except for light, heat and other forms of radiation, a sealed aquarium is a closed system. It was, I suddenly understood, a perfect reflection of the same kind of closed system as our planet. Various bits of knowledge, about population growth, deforestation, industrialization and pollution came together in a flash of intuitive, gestalt understanding. I suddenly knew that we were on the way towards making the Earth incapable of sustaining our civilization -- maybe even our species. We were on the way towards destroying ourselves, and we might not even know when we had passed the point of no return until years afterwards, when it would be far too late.
I remember stumbling blindly out into the hallway when the bell rang, leaning against the wall, numb with shock at the horror of that realization. I don't remember if I made it to my next class.
I was 12 years old when I had that terrible insight. It was five long years before I learned that there was anyone else on the planet who understood, who believed, who knew what I knew.
Some of you will already have recognized the book that meant so much to me back then... that still informs my understanding of ecology -- and economics -- even today. The Limits to Growth.
The Limits to Growth was an odd little book. It was published by Universe Books in 1972, but that makes it sound way too normal. A quote from its Wikipedia entry may help:
The Limits to Growth is a 1972 book about the computer modeling of unchecked economic and population growth with finite resource supplies.  Funded by the Volkswagen Foundation  and commissioned by the Club of Rome it was first presented at the 3. St. Gallen Symposium. Its authors were Donella H. Meadows, Dennis L. Meadows, Jørgen Randers, and William W. Behrens III. The book used the World3 model to simulate  the consequence of interactions between the Earth's and human systems.Ah, the combination of techno-speak with that casual reference to a mysterious group -- the Club of Rome -- now that's a better reflection of both the strength and the strangeness of this little book.
If you're interested in learning about the Club of Rome and how The Limits to Growth came to be written, there's a good article in The Nation here.
So how did this book change my life? In a number of ways, actually; but there's one overarching change that probably made the most difference to me at the time. It took that intuitive, gestalt sense of the planet as a sealed box with far too much waste building up in it, and translated it into a series of data sets and new ways of thinking about that kind of data. That change, which I referenced in the subtitle, took me from what felt like helpless anxiety to a sense that there were ways to communicate about, and potentially even DO something about, the danger that I sensed looming ahead for humanity and the entire biosphere.
Among other things, this book taught me to understand exponential growth. Edward Teller said, "The extinction of the human race will come from its inability to EMOTIONALLY comprehend the exponential function." He may have been right. But maybe we can find new ways to teach it. For me, it came easily, but that's because of my odd way of thinking.
Most people think primarily either in pictures or in words. I think primarily in the kinesthetic sense. If you talk to most people about a pond, they either think about it in words or get a visual image of it. I get a kinesthetic sense of land sloping down to an area filled with water. The land feels solid. The water is less so, but still has substance -- both volume and mass. So for me, the metaphor of a pond being filled by exponential increments created an internal feeling of the sudden shift... of how you go for nearly a month with the tiny amounts getting only a little bit bigger, and then, suddenly, in the last 4 days, it's 1/8 full, then 1/4, then 1/2, then BAM! It's full. No more room. When 5 days ago it was almost empty. That solid sense of mass, doubling, and doubling again, totally filling the pond so suddenly has stayed with me for 40 years. I get exponential growth. There must be a way to teach it so that visual and verbal thinkers get it, as well.
Another thing The Limits to Growth did for me was give me a way of looking at economics from a more realistic perspective. I know that infinite growth is not possible, so the focus, as with ecology, needs to be on sustainability.
Oh, in case you're wondering how accurate the book's predictions were, the Smithsonian Magazine took a look at that here.
Spoiler alert: they were frighteningly accurate.
The Limits to Growth taught me to look at our situation as a web of interlocking systems that can be affected not only for ill, but also for good. Yes, it's going to take a while to transition to renewables, but in the meantime Allan Savory is figuring out ways to reverse desertification in ways that can help to sequester both CO2 and methane. The dynamic balance between positive and negative effects of technology, and the building of a movement that is attracting bright young minds, give me hope that we can go a long way towards mitigating the coming disaster. This book gave me the context, the ability to look at all these different elements, instead of just being overwhelmed by the horror of what we're facing.
So the The Limits to Growth changed my life in 1972, and continues to have an impact today. I credit those researcher/authors with the fact that I can see the disaster coming and instead of being overwhelmed by despair I keep looking for what can be done, or invented, or changed, or who can be educated... Because it may be a closed system, but it's a COMPLEX closed system, and everything we do can affect everything else... so it ain't over till it's over.