Half-Earth: Our Planet’s Fight for Life

“‘The Anthropocene,’ far-distant geologists might say, ‘unfortunately married swift technological progress with the worst of human nature. What a terrible time it was for people, and for the rest of life.’”

Most epochs within the Cenozoic era last at least several million years. The final epoch of this era, recognized by geologists, is the Holocene. It began around 12,000 years ago and is marked by the retreat of glaciers, climate amelioration, and the spread of humans around the world. In a flash of geological time, humans have altered the climate and environment to such an extent, through both technological advances (e.g., factories that result in increased pollution and machinery that can clear an entire section of a rainforest in a matter of weeks) and preferences for short-term decisions over long-range planning, that some researchers argue we should end the Holocene and replace it with a new geological epoch, the Anthropocene. Wilson echoes this view throughout the book.

“The biosphere does not belong to us; we belong to it.”

Some individuals (researchers and laypeople alike) believe that humans are unique compared to the rest of life, partly due to our large and complex brains and ability to plan. Because of these traits, they feel that humans are nature’s supreme achievement and, hence, worthy of acting as a supreme ruler over all other species. Wilson dismisses this notion and continually reminds readers that humans are biological organisms. Just like all other species, we are the product of millions of years of evolution by natural selection. Thus, humans are a part of the biosphere and not rulers of it.

“But for the moment, conservation scientists look at a world census as a dilemma wrapped in a paradox. The amount of Earth’s biodiversity, we have found, is like a magic well. The more species humanity extinguishes, the more new ones are discovered.”

An important recurring element of Wilson’s argument is that Earth remains a little-known planet, and it may remain this way if we do not stop the mass extinction event. We continue to identify new species—in fact, scientists will not complete the global census for several more decades at least—as well as those that are disappearing. Because we do not know the actual number of species alive, we do not know the true number we are extinguishing. To Wilson, this is the “dilemma wrapped in a paradox.” He warns that if humans continue down this path of destruction, we, and our domesticated animals and plants, will be the only living organisms left on Earth. This will be a truly lonely existence, according to Wilson, given the rich biodiversity that presently surrounds us.

“The result is a bitter irony: rhinos are being driven to extinction even though their horn has no more medicinal value than a human fingernail.”

Wilson spends a significant portion of his text focusing on how humans are obliterating the planet’s living species for trivial reasons. An eye-opening example of this is Wilson’s elegy for the rhinos. Rhinos are being driven to extinction for their horns, which are used in traditional Chinese medicine. According to Wilson, population increases have led to increased demand for rhino horns. The irony of this situation, says Wilson, is that horns have no medicinal value; thus, humans are senselessly killing them. In this chapter, and elsewhere, Wilson’s raw emotion over these senseless extinctions encourages readers to contend with the true scale of human destruction. 

“In order to bring the recent mollusk losses into focus for you, I offer here the names of all nineteen of the river mussel species known to have been driven to extinction: Coosa elktoe, sugarspoon, angled riffleshell, Ohio riffleshell, Tennessee riffleshell, leafshell, yellow blossom, narrow catspaw, forkshell, southern acornshell, rough combshell, Cumberland leafshell, Apalachicola ebonyshell, lined pocketbook, Haddleton lampmussel, black clubshell, kusha pigtoe, Coosa pigtoe, stirrup shell. Rest in peace.”

One central tenet in Wilson’s text is that humans are unfamiliar with the names of most invertebrates, especially compared to vertebrates. Generally, the public can name important US vertebrate species that have gone extinct, such as the passenger pigeon, ivory-billed woodpecker, and California grizzly bear. In contrast, very few laypeople could name invertebrates that are extinct. Throughout the book, Wilson tries to rectify this lack of knowledge by providing lists, such as the one above, of extinct invertebrates. This technique highlights the full scale of destruction humans are causing to the wildlands. 

“When these and other species disappear at our hands, we throw away part of Earth’s history. We erase twigs and eventually whole branches of life’s family tree. Because each species is unique, we close the book on scientific knowledge that is important to an unknown degree but is now forever lost.”

Wilson continuously emphasizes how living organisms are braided together within an ecosystem. When one species disappears, their disappearance not only removes them from their evolutionary tree but also has a ripple effect, causing others to also disappear. Given our current limited knowledge of the true richness of Earth’s biodiversity, we are losing scientific knowledge that, in some cases, we do not even realize is “now forever lost.” Contrary to anthropocentrists, Wilson dismisses the notion that species that have gone extinct can be brought back using cloning. Thus, we are forever erasing part of Earth’s history.

“Hundreds of millions of years in the making, and we’re extinguishing Earth’s biodiversity as though the species of the natural world are no better than weeds and kitchen vermin.”

The current rate of extinction is up to 1,000 times faster than during the pre-human era. Wilson continuously challenges humans’ disregard for nature and the senseless ways in which we are obliterating life. Humanity does not seem to grasp how interconnected life truly is.

“Like an accident patient in emergency care continuing to hemorrhage and with no new supply of blood available, stabilization is out of reach and further decline and death are inevitable.”

The current conservation movement is not working fast enough to stop the Sixth Extinction, primarily because it focuses on the most endangered habitats and species. The birth rate of species is also simultaneously decreasing. By continuing to only implement the same conservation strategies, we will not stop the inevitable death of the natural world. To Wilson, the magnitude of the problem calls for a “new supply of blood” or new solution: reserving half of the planet’s surface for nature.

“Having risen above all the biosphere, set to alter everything everywhere, the wrathful demon of climate change is our child that we left unrestrained for too long.”

Human activities, such as deforestation, agriculture, burning of fossil fuels, and waste decomposition, have increased greenhouse gases in the atmosphere. The consequences of changing the natural atmospheric greenhouse are not localized to one country or region but will be felt across the world. People have suspected for decades that human activity could alter climates and environments, potentially irreversibly, but politicians and some members of the public ignored these warnings. We are now grappling with the effects of human-drive climate change. Thus, Wilson argues, the situation that the global community currently faces is entirely the fault of humans.

“The decline of biodiversity has been more like the gradual dimming of light than the flick of the switch.”

The spread of modern humans around the world has been followed by the decline of species. For example, Paleoindians, the first Americans, played a role in the extinction of megafauna in North America 11,000 years ago (natural changes to the climate and environment were also important factors). Wilson captures the essence of this process in this passage. Biodiversity is not disappearing suddenly but has been dimming slowly for thousands of years.

“We are the stewards, not their owners.”

Throughout the text, Wilson makes clear he does not buy into the notion that nature should serve humans. Rather, he argues that we are the stewards of nature. By setting aside one-half of the planet for nature reserves, we would provide hope for this stewardship.

“Every species still alive is precious to us. Naturalists live for our Lord God moment. We want to save the experience for all generations to come.”

Wilson clearly has a deep passion for nature, a characteristic that he says all naturalists have. All naturalists want their “Lord God moment,” in which they discover a new species or rediscover one that was thought extinct. However, such a discovery is not for personal gain. Rather, it continues to build humanity’s knowledge of the richness and uniqueness of biodiversity, something that current and future generations will enjoy.

“We break many threads, and change the ecosystem in ways still impossible to predict.”

Human-driven extinction is destroying the webs of life that interconnect to form an ecosystem. By allowing one species to die, we are erasing not just its web, but also the “web of relationships it maintained in life” (106). Unfortunately, scientists, according to Wilson, do not fully understand these relationships and interactions. Thus, it is hard to predict what consequences species extinctions will have on ecosystems.

“Whereby the great cosmic cycle might give intelligence on Earth a second chance.”

This startling statement invites the reader to stop and ponder what would happen if we continue down this path of destruction and wipe out not just other species but our own. Wilson suggests that not all life will be destroyed. Single-celled organisms that live within the deep biosphere, of which there are millions, have a high chance of survival. These microbes might eventually make their way to the surface and evolve into more complex multicellular life, even possibly something akin to humans.

“My consultants and I are well aware that our ‘best places’ list could be multiplied many times over, but I believe that we have captured most of the very best. Together we make the point that even though extinction rates are soaring, a great deal of Earth’s biodiversity can still be saved.”

Prior to Chapter 15, Wilson spent significant time discussing the incredible species that are either close to or forever extinguished. In many ways, Chapter 15 is like a breath of fresh air. Wilson and his consultants—18 of the world’s senior naturalists—describe the “best places” around the world, due to their uniqueness, richness, and need for protection and further study. These places demonstrate that there is still biodiversity that can be saved. Wilson also presents an optimistic tone. He strongly believes that we can and will save much of life from the Sixth Extinction.

“Being very big, ancient, and tropical, Madagascar harbors a very large and unique fauna and flora, with 70 percent or more of its species found nowhere else. (The most recent figure for the fourteen thousand plants is 90 percent.) Like Cuba, Hispaniola, and the Galápagos, Madagascar is a living laboratory for the observation of adaptive radiation, defined as the origin of a large array of species from a single species fortunate enough to colonize the island (in this case usually flying or floating over from Africa).”

This passage is one of the numerous pieces of evidence Wilson presents to highlight the uniqueness and richness left in the biosphere. Madagascar, like other places discussed in Chapter 15, has an incredible amount of biodiversity, and the majority of its species are found nowhere else in the world. If humans extinguish Madagascar’s unique ecosystem and the species within, we will not find them elsewhere. Thus, they will be gone forever. This situation is not unique to Madagascar; it is the same for places all over the world. 

“The history of species is thereby an epic.”

To Wilson, each surviving species, including humans, is a champion, like Odysseus in Homer’s Odyssey. Each species has successfully overcome challenges. The challenge of life is to better adapt to the environment and produce more offspring than other species, enabling our lineage to outcompete and continue over other species. The history of each species, identified by reconstructing its evolutionary family tree, is an epic. It is a narrative of the adaptations, similar to adventures and deeds, of champions.

“Earth’s biosphere is like the orb of a spiderweb though which a bird has accidentally flown. Beautiful order has instantly turned into chaos. The spider knows this risk instinctively, and builds across part of the web a band of silk so conspicuous that it virtually shouts at intruders to turn aside.”

In several places in the book, Wilson describes how each ecosystem is a web of organisms, specialized for their habitat and interconnected. Through human activity, we, like a bird that has flown through a spider web, are disrupting these individual web strands or relationships by causing populations to decline and even disappear. These actions are throwing entire ecosystems into chaos. However, nature is not passively allowing this chaos. There are warning signs all around us, such as prolonged heat waves, severe weather, and melting glaciers—nature is destabilizing. In this way, nature is like the spider, which conspicuously places a silk band so that birds can see the web and avoid flying into it. However, both the bird and humans ignore these warnings, turning order into chaos.

“Each project is special unto itself. Each requires knowledge and love of the local environment shared by partnerships of scientists, activists, and political and economic leaders.”

There is no one-size-fits-all solution for conservation projects. Just because a strategy worked in one habitat does not mean it will be successful in another. To Wilson, the strongest conservation strategies are locally led by individuals who have the knowledge, passion, and courage to make them succeed in their own communities.

“The extinction rate our behavior is now imposing on the rest of life, and seems destined to continue, is more correctly viewed as the equivalent of a Chicxulub-sized asteroid strike played out over several human generations.”

At first glance, it might seem ridiculous to compare the Chicxulub Impact Event, which caused the extinction of three-quarters of all species, to humanity’s footprint. However, if we do not stop the current extinction path we are on, between 30% and 50% of species living today could be extinguished over the next few decades. Like the Chicxulub asteroid, humans’ alteration of the climate and environment is happening in a flash of geological time. Our impact on life could be just as catastrophic as that of the asteroid.

“Living Earth, all of it, can continue to breathe.”

By conserving one-half of the planet to nature, we are allowing Earth to “continue to breathe.” Wilson’s solution will provide species that were endangered and close to extinction habitats in which to grow. Local species that were being outcompeted by invasive species will escape their fate of extinction. The unknown species will not disappear before scientists have the chance to study them. While Earth will lose some species, humans will ultimately prevent mass extinction.

“The biosphere and the ten million species that compose it will no longer be treated as a commodity, but as something vastly more important—a mysterious entity still beyond the boundaries of our imagination yet vital to long-term human existence.”

Wilson believes that through the digital and economic revolutions currently occurring, we will reduce our ecological footprint. In so doing, we will recognize that nature is not meant to serve humans. Rather, it is an entity that we still know little about and that is worth understanding, both because of human’s innate curiosity about the world and because the natural world is key to our own survival.

“The reason is that we are thinking organisms trying to understand how the world works. We will come awoke.”

Humans can be selfish and often make decisions based on individual desires rather than thinking about how these decisions will impact the group and future decisions. Yet, humans also have the capacity to plan for the future and act altruistically. In the end, we are interested in understanding the world around us and will come to understand the value of life. Once we do this, according to Wilson, there will be a natural shift to wanting to conserve life. Wilson is optimistic and believes that humans will stop the Sixth Extinction.