It’s not unusual for species to go extinct; it happens all the time. In fact, scientists estimate that at least 99.9% of all species of plants and animals that have ever lived on Earth are now extinct. That’s pretty amazing, considering how many species still exist—up to 8.7 million, according to some experts.

Mass extinction events, however, are not so common. A mass extinction event is when more than half of all species living at a given time go extinct over a relatively short period. The American Museum of Natural History found five significant mass extinction events in the Earth’s history that it thought were worth highlighting on the museum’s website. The largest of these happened about 250 million years ago, when up to 95% of existing species died out. Another that people may find particularly noteworthy occurred 65 million years ago. That one took out the dinosaurs, marking a major turning point in history.

What hasn’t happened in the past is a mass extinction event caused by humans. However, Richard Heinberg, author of the soon-to-be-released book titled Power: Limits and Prospects for Human Survival, thinks that may be coming, and some of the reasons are detailed in his 416-page book.

“The book is a ‘big picture’ book, and I address three huge questions in it. One is: How did we—just one species—come to overpower the rest of nature to the point where we’re changing the climate and triggering what looks like it may be a mass extinction event? The second question is: How have we come to oppress one another in so many and so brutal ways? And the third is: Is there any way we can come to terms with power in such a way as to turn things around?” Heinberg said as a guest on The POWER Podcast.

Heinberg said people around the world must switch from fossil fuels to alternative energy sources to limit climate change, but he was pessimistic about the prospects for doing so quickly enough to make a difference in the long term. “It’s going to be very, very difficult to do that in fact, and for a number of reasons,” said Heinberg. “One, of course, is just the fact that solar and wind, which are our main candidates for replacing fossil fuels, they produce electricity, but electricity is only about 20% of global energy usage. So, the other 80%, we use solid, liquid, and gaseous fuels for agriculture and transportation, and industrial processes like smelting metals, and making cement for concrete, and on, and on, and on—a lot of high-heat industrial processes. Those things are going to be hard to electrify.”

He noted that there are ways to use electricity to make synthetic fuels, including producing hydrogen through electrolysis, but most of these processes are very inefficient and expensive. Furthermore, it would take an enormous amount of new infrastructure to accommodate the consumption today.

“If we’re going to make those fuels in any considerable quantities,” he said, “we would have to build all this infrastructure, mostly from scratch, and in a very short amount of time. We’re talking about the next 10 to 20 years that we’ll need to basically reduce our net emissions virtually to zero, if we’re going to avert catastrophic climate change. There’s almost no way you can build that amount of infrastructure without actually, and ironically, causing another burst of greenhouse gas emissions, because building all of that infrastructure will take energy. And where’s the energy going to come from? Well, 80% of it’s going to come, at least in the initial stages, from fossil fuels.”

The only way to “get to the other side,” according to Heinberg, is for people in industrial countries such as the U.S. to reduce their overall energy usage pretty substantially. “That sounds really daunting, but it certainly is possible to do,” he said. “Europeans use half the energy that Americans do, and yet their quality of life is quite acceptable by anybody’s standards. So, we’re going to have to find ways of providing basic human needs in ways that use the least amount of energy, and then supply renewable energy for those purposes.”

The world’s growing population also presents a challenge. At the beginning of the Industrial Revolution, there were fewer than a billion people on Earth. Today, there are almost 8 billion, and the United Nations predicts the world’s population could reach 11 billion by the turn of the century. Dramatically cutting total energy usage while adding up to 3 billion energy consumers is not an easy task. “There’s no way out. We’ve got to deal with the fundamental ecological dilemma of population and consumption versus nature’s limits,” Heinberg said.

Ironically, fossil fuels may be helping to limit population growth, although not in a heathy way. Heinberg said sperm counts in men around the world are declining, and at least some of the decline can be attributed to environmental pollution. “We’ve saturated air and water with trace amounts of hormone-mimicking chemicals—most of them derived from fossil fuels—that are affecting reproduction rates, not only in humans, but also in other animals and birds and even insects,” he said. “If the current rate of decrease continues, then the average male sperm count will reach zero—this sounds pretty dramatic—but probably before 2050. So, in that sense, the population problem could be solvable, but certainly not in a way that any of us would prefer.”

In the meantime, the changing climate could also result in mass migrations. As areas become too hot for humans and other animals to live in, and water becomes scarcer, people will have to move to more habitable locations. Heinberg suggested the problem could be a politically fraught nightmare.

“I speak frequently to experts, not just in climate science, but in other environmental fields and social fields and so on. And everyone that I talk to is really, really concerned about where all of this is headed. So, if you’re worried, you’re not alone, the experts are worried too. But, we really have to start talking honestly with each other about all of this and getting our heads out of the sand because it’s just too easy to live in denial,” Heinberg said. “We’re going to have to step up to the plate and really show that we’re a species that deserves to survive.”

To hear the full interview, which includes much more about Heinberg’s book, and how power usage has altered the environment and affected all species on Earth, listen to The POWER Podcast. Click on the SoundCloud player below to listen in your browser now or use the following links to reach the show page of your favorite podcast platform:

For more power podcasts, visit The POWER Podcast archives.

Aaron Larson is POWER’s executive editor (@AaronL_Power, @POWERmagazine).