Humans have existed on this planet for a relatively short time, yet we’ve had a major impact on it, dramatically altering its biodiversity and shifting its global climate in only a few centuries. The burning of fossil fuels has cooked the globe so much that ecosystems are threatening to fall completely out of balance, which could accelerate the ongoing mass extinctions caused by our predilection for exploiting nature.

There’s a very distinct possibility we could trigger our own extinction or, at the very least, greatly reduce our population while completely altering the way we currently live. Little things like going outside during daylight hours or growing food in the dirt could become relics of the past, along with birds, insects, whales and many other species. War, famine, pestilence and death — that dreaded equine quartet — threaten to topple our dominance on this planet. We are destroying our own home, sawing off the very branch we rest on.

Those who refute this reality, or climate change deniers, misinterpret the same sets of data showing a clear anthropological cause as being part of the “natural” cycle of the planet. Things are warming, they argue, and that is normal. Only, it really isn’t normal.

Climatologists and scientists have been sounding the alarm for decades: Global temperatures and planetary homeostasis are spiraling out of control, and we’re to blame. The climate crisis is no longer a hypothetical future. It’s the tangible present, and the evidence is clear in every grueling heatwave, not-so-uncommon “freak” storm and raging wildfire.

On the opposite extreme is a vocal minority, the accelerationists and nihilists who accept that humanity is overwhelmingly destructive to nature, but argue our extinction would be a welcome relief. I received many such comments on social media after interviewing Peter Ward, a paleontologist and professor at the University of Washington, about his “Medea hypothesis,” a theory that life is not a benevolent force and often causes its own extermination. Many species in Earth’s history became so successful that they wiped themselves out — and we could do the same.

In response to that article, many readers said something such as, “Humans are a virus and should be eradicated.” Obviously, inducing human extinction is an outcome for which only a very cynical personality would advocate. But what about the first part of that statement? Are humans really like a virus, a pathogen, a cancer?

Dr. Warren Hern, a Colorado-based physician and author of the new book “Homo Ecophagus: A Deep Diagnosis to Save the Earth,” argues that human civilization indeed has many similarities with cancer. This isn’t a metaphor, but rather a literal diagnosis — and it can be addressed in the same way that an actual cancer diagnosis can be the first step to treatment.

Salon recently spoke with Hern about his new book, which acts partially as a memoir, textbook, dire diagnosis and poetic ode to a disintegrating planet, discussing the implications for such an urgent prognosis, a new name for the human species that reflects our true nature and how we can still fix this crisis.

This interview has been condensed and lightly edited for clarity.

My opinion is that humans are part of nature — we are not separate from it. After I came across your book, I began asking myself, “Are humans really a cancer on the planet?” I thought, “Aren’t we part of this whole ecosystem?” I initially set out to disprove what you’re saying, but the argument you make is so extremely convincing. I know from your writing that when you were first conceptualizing the notion that humans are a cancer on the planet, it was very unpopular. But now it seems like this idea has earned some mainstream acceptance. Is that true?

This is a fundamental scientific and philosophical question. And, first of all, I agree with you that we are part of nature. We evolved in a natural ecosystem, and we have obviously very intimate close ties with other species, other animals. Humans are unique in that they have culture, although we’re learning that other animals have certain levels of culture also, like whales. So, we are really not unique in that sense, but we have a different and higher level of culture that allows us to dominate other species and ecosystems.

These are cultural adaptations that allow us to survive, but they have become malignant maladaptations because they are now threatening our survival and millions of other species. We have essentially made a decision at this point as a species to go extinct. That’s what we’re doing — we’re eliminating our biosphere and our planetary support system. Consciously or not, and I think mostly unconsciously.

When I first came onto this in the late ’60s, I was horrified. It’s not an analogy; nobody ever died from an analogy. It’s a diagnosis, and that’s different. The diagnosis is the same as the hypothesis. The guy comes into the emergency room with a sore belly, and he has right lower quadrant pain. Your diagnosis is appendicitis until proven otherwise. But that’s a hypothesis because he might have some other disease, or if it’s a woman, they might have an ovarian cyst.

I work with the idea from Karl Popper that science is not advanced by proving anything, but by disproving false hypotheses. The purpose of a hypothesis is to explain reality and predict events. This hypothesis [humans as a cancer] explains what we see going on in reality around us —  and has for a long time —  and it predicts what is going to happen. And that means the prognosis, in medical terms, for cancer is death. The cancer continues until the host organism dies.

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The difference between us and a cancer — the only difference — is we can think, and we can decide not to be a cancer. If the diagnosis is correct, things will continue until we are extinct. The biosphere can’t go extinct; it can’t die, but we can alter it to the point that we can no longer survive. And that will take out millions of other organisms. Clearly, plenty of organisms are going to survive that process. They might even be more intelligent than us. I don’t know.

That’s sort of the general picture. And whether people accept this or want to even listen to it is another thing. For example, in the book, I talk about the guy who took over the anthropology section at AAAS [American Association for the Advancement of Science] back in the early ’90s. He didn’t like this idea, and he wanted them to drop it from the schedule because his wife had cancer and he was very offended by it. I told him, “Well, I’m really sorry that your wife has cancer, and I certainly hope she recovers. This doesn’t have anything to do with your wife’s cancer.”

I hope people can see that because it’s such a good diagnosis. I mean, it really does fit the bill. You look at maps of cities and tumors, and you can see how they kind of grow similarly. But the similarities don’t end there.

The basic premise is that humans have the capacity of developing culture, and that has millions of manifestations, everything from language and speech and mathematics to constructing shelters, building weapons and having medical care to keep us alive. These adaptations have allowed us to go from a few separate species of skinny primates wandering around in Africa a couple of million years ago to being the dominant ecological force on the planet to the point we’re changing the entire global ecosystem.

These cultural adaptations have now become maladaptive. They do not have survival value. And they are, in fact, malignant maladaptations because they’re increasing in a way that cancer increases. So, this means that the human species now has all of the major characteristics of a malignant process. When I was in medical school, we had four of them that were identified: rapid, uncontrolled growth; invasion and destruction of adjacent normal tissues — in this case, ecosystems; metastasis, which means distant colonization; and dedifferentiation, which you see very well in the patterns of cities.

That’s only one example. We now have 10 or 15 other new characteristics of cancer, and the human species fits all of them. And so the disturbing thing about this? If you have any two of the first four characteristics of cancer, it’s cancer until proven otherwise. And cancer does not stop until the host organism has ceased to function, which for our purposes is the biosphere.

Now, I have given the book the name “Homo Ecophagus.” That is my new name for the human species, which currently has the scientific name of Homo sapiens sapiens, or wise, wise man, which makes us the most misnamed species on the planet. Homo ecophagus means the man who devours the ecosystem — and that’s what we are doing.

We are in the process of converting all plant, animal, organic and inorganic material on the planet into human biomass and its adaptive adjuncts or support systems. The evidence for that is all around us.

So, that’s the basic idea in a nutshell, and then the rest of the book is simply manifestations of this malignancy and an explanation of the analysis. And so, the next question is: Can we do anything about this? Should we do something about this? It’s very hard under the circumstances, for example, to think about Vladimir Putin sitting down with Zelensky if they can fix the ecosystem in Ukraine.

Right, it’s a very, very difficult problem. It’s the biggest problem our society faces right now. Literally, nothing else matters if we don’t address this problem.

That’s the point: It’s an existential crisis. Yes.

I have to say that it seems like we’re not going to solve this problem. I don’t want to be negative and despair that we’re all simply going to die from climate change. I recently made a move across the country from California to Illinois. Everywhere you go, you get that dedifferentiation that you speak of, where everything looks the same. Every freeway has the same strip malls. You see all these people in these giant pickup and semi trucks and all this overconsumption. I just don’t see people giving it up. I just don’t see it happening. Not fast enough, at least.

This is what I call the “ecophagic imperative.” Robert Ardrey, a brilliant anthropologist, about 40 or 50 years ago wrote a number of outstanding books. One is called “The Territorial Imperative,” which is about how humans have an imperative need to have and expand their territories.

One of the most lurid manifestations of what we have right now is Donald Trump. Another one is Putin and the war on Ukraine, but humans have been doing this forever. And now we are like a malignant melanoma that is devouring the Earth instead of one that is killing the individual patient. We are devouring the ecosystem. We have an imperative to do that. Look at the open pit mines that we have of various kinds. The whole alternative energy programs depend on destroying certain ecosystems to get the rare metals that we need to do that stuff.

I do not want to be negative, either. I’m basically an optimistic and positive person. I’ve been my whole life. The Intergovernmental Panel on Climate Change gives us a list of horribles, and it gets more horrible every year. But what’s the underlying dynamic? I say this is a malignant process going on for hundreds of thousands of years.

This is not new. When the Australian Aborigines arrived on the continent of Australia, they started changing the ecosystem in very dramatic ways, and a lot of species went extinct. My colleague here at the University of Colorado, Giff Miller, has been one of the people showing that it happened in Australia. It happened in the Pacific Islands. It happens every place. Humans have made other species extinct wherever they show up.

Of course, it takes individual actions. The obvious side to that is people can make changes in their lives. I’m in Boulder, Colo, for example, where they have a lot of recycling going on, and people are very conscious of that. But, at the same time, you have China putting in a coal-fired power generation plant every week. So, it’s very hard to see how all these individual actions can really have that effect that we want.

Do you have hope for the future, or maybe feel despair about everything? I often get a little bit paralyzed and feel like there’s no point to anything, like we’re all just going to go off the cliff. I’m hoping something will change, that something will shift on a major level, that we’ll all kind of come together on this issue. But I feel like I’ve been waiting for that moment for years.

It’s hard to know how to answer your question when you ask me, “Is there hope?” One of my main answers — which is true — is that young people like you give me hope, people who are looking at this stuff and thinking about it and figuring out what to do. When I look at the current political scene in the United States, it’s very hard to be optimistic because we have a violent fascist movement that occupies the attention of at least a third, if not more, of the population, supporting a man who is a sociopathic criminal.

I think that we make the decisions about these situations — the environment and our survival — through our political process. I want to be optimistic. Let me just share a little example of something with you. A week ago, I went to New Mexico to attend a special memorial service for Dave Foreman.

Dave Foreman started the organization Earth First! with a couple other people. He was what we call a radical environmentalist, and he was associated with Edward Abbey, who wrote “The Monkey Wrench Gang.” And part of their idea was you throw a monkey wrench into this process to stop it. OK, very romantic idea. Very exciting, but how much did they accomplish with that?

The meeting was held in a campground outside of Los Alamos, and we were a scruffy-looking bunch of backpackers and tree huggers. I felt right at home with these wonderful people, who were some of the hardcore environmentalists of this country, and people who really, really were dedicated, spent their lives working on protecting the environment. We’ve been talking about people with advanced degrees, with PhDs in ecology and biology, wolf conservation, I don’t know what else.

They were an impressive bunch of people. I enjoyed meeting them, and I participated in this meeting. I admire Dave, who was a friend of mine. And I have his books, and they’re worth reading. OK, this is a highly energetic, wonderful, dedicated, altruistic group in this country. What’s been happening since they started Earth First!? Things are a lot worse than they were.

And it’s very hard to see how that has really influenced the broad scale of things, even though they’ve had a lot of very specific local victories. More people need to understand that we are in an impending extinction crisis for ourselves and for the rest of the ecosystem and other species. We are destroying the planet as we speak — as rapidly as possible — and that must stop. We must find ways to do things differently, and that’s going to make big changes in our lives.