As of this month, the UN World Meteorological Organization, NASA, and the National Oceanic and Atmospheric Administration (NOAA) all confirmed that 2015 was the warmest year on record by “a big margin,” beating the previous record set by 2014. In fact, fourteen of the hottest years on record have all occurred after 2000. This is one of the primary reasons that the Bulletin of Atomic Scientists recently announced that the minute hand of the Doomsday Clock, which represents our collective nearness to a global catastrophe, will remain a mere three minutes before midnight (or doom). As the Bulletin put it, “the fight against climate change has barely begun, and it is unclear that the nations of the world are ready to make the many hard choices that will be necessary to stabilize the climate and avert possible environmental disasters.” The result is that “The world situation remains highly threatening to humanity.”

The other greatest threat to humanity stems from nuclear weapons — the very first anthropogenic “existential risk” in human history. But I would argue that, as horrific as a nuclear war anywhere in the world would be, climate change is a much more urgent and fundamental problem. Why? Because the consequences of climate change will nontrivially influence the probability of conflicts breaking out in the first place, as state and nonstate actors become increasingly desperate for dwindling resources and land. Climate change is, as some have put it, a “conflict multiplier” that will both exacerbate existing struggles and foment brand new geopolitical tensions in the twenty-first century. Consequently, while the threat of nuclear weapons cannot be ignored, our primary goal ought to be mitigating the effects of greenhouse gases in the atmosphere.

But there’s another global catastrophe that the Bulletin neglected to consider — a catastrophe that will almost certainly have conflict multiplying effects no less than climate change. I’m referring here to biodiversity loss — i.e., the reduction in the total number of species, or in their population sizes, over time. The fact is that in the past few centuries, the loss of biological diversity around the world has accelerated at an incredible pace. Consider the findings of a 2015 paper published in Science Advances. According to this study, we’ve only recently entered the early stages of the sixth mass extinction event in life’s entire 3.5 billion year history. The previous mass extinctions are known as the “Big Five,” and the last one wiped out the dinosaurs some 65 million years ago. Unlike these past tragedies, though, the current mass extinction — called the “Holocene extinction event” — is almost entirely the result of a one species in particular, namely Homo sapiens (which ironically means the “wise man”).

"If the environment implodes under the weight of civilization, then civilization itself is doomed."

But biodiversity loss isn’t limited to species extinctions. As the founder of the Long Now Institute, Stewart Brand, suggests in an article for Aeon, one could argue that a more pressing issue is the reduction in population sizes around the globe. For example, the 3rd Global Biodiversity Report (GBO-3), published in 2010, found that the total abundance of vertebrates — a category that includes mammals, birds, reptiles, sharks, rays, and amphibians — living in the tropics declined by a whopping 59% between 1970 and 2006. In other words, the population size of creatures with a spine more than halved in only 36 years. The study also found that farmland birds in Europe have declined by 50% since 1980, birds in North America have declined by 40% between 1968 and 2003, and nearly 25% of all plant species are currently “threatened with extinction.” The latter statistic is especially worth noting because many people suffer from what’s called “plant blindness,” according to which we fail “to recognize the importance of plants in the biosphere and in human affairs.” Indeed, plants form the very bottom of the food chains upon which human life ultimately depends.

Even more disturbing is the claim that amphibians “face the greatest risk” of extinction, with “42% of all amphibian species … declining in population,” as the GBO-3 reports. Consistent with this, a more recent study from 2013 that focused on North America found that “frogs, toads and salamanders in the United States are disappearing from their habitats … at an alarming and rapid rate,” and are projected to “disappear from half of the habitats they currently occupy in about 20 years.” The decline of amphibian populations is ominous because amphibians are “ecological indicators” that are more sensitive to environmental changes than other organisms. As such they are the “canaries in the coal mine” that reflect the overall health of the ecosystems in which they reside. When they start to disappear, bigger problems are sure to follow.

Yet another comprehensive survey of the biosphere comes from the Living Planet Report — and its results are no less dismal than those of the GBO-3. For example, it finds that the global population of vertebrates between 1970 and 2010 dropped by an unbelievable 52%. Although the authors refrain from making any predictions based on their data, the reader is welcome to extrapolate this trend into the near future, noting that as ecosystems weaken, the likelihood of further population losses increases. This study thus concludes that humanity would “need 1.5 Earths to meet the demands we currently make on nature,” meaning that we either need to reduce our collective consumption and adopt less myopic economic policies or hurry up and start colonizing the solar system.

Other studies have found that 20% of all reptile species, 48% of all the world's primates, 50% of all freshwater turtles, and68% of plant species are currently threatened with extinction. There’s also talk about the Cavendish banana going extinct as a result of a fungus, and research has confirmed that honey bees, which remain “the most important insect that transfers pollen between flowers and between plants,” are dying out around the world at an alarming rate due to what’s called “colony collapse disorder” — perhaps a good metaphor for our technologically advanced civilization and its self-destructive tendencies.

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Turning to the world’s oceans, one finds few reasons for optimism here as well. Consider the fact that atmospheric carbon dioxide — the byproduct of burning fossil fuels — is not only warming up the oceans, but it’s making them far more acidic. The resulting changes in ocean chemistry are inducing a process known as “coral bleaching,” whereby coral loses the algae (called “zooxanthellae”) that it needs to survive. Today, roughly 60% of coral reefs are in danger of becoming underwater ghost towns, and some 10% are already dead. This has direct consequences for humanity because coral reefs “provide us with food, construction materials (limestone) and new medicines,” and in fact “more than half of new cancer drug research is focused on marine organisms.” Similarly, yet another study found that ocean acidification is becoming so pronounced that the shells of “tiny marine snails that live along North America’s western coast” are literally dissolving in the water, resulting in “pitted textures” that give the shells a “cauliflower” or “sandpaper” appearance.

Furthermore, human-created pollution that makes its way into the oceans is carving out vast regions in which the amount of dissolved oxygen is too low for marine life to survive. These regions are called “dead zones,” and the most recent count by Robert Diaz and his colleagues found more than 500 around the world. The biggest dead zone discovered so far is located in the Baltic Sea, and it’s been estimated to be about 27,000 square miles, or a little less than the size of New Hampshire, Vermont, and Maryland combined. Scientists have even discovered an “island” of trash in the middle of the Pacific called the “Great Pacific Garbage Patch” that could be up to “twice the size of the continental United States.” Similar “patches” of floating plastic debris can be found in the Atlantic and Indian oceans as well, although these are not quite as impressive. The point is that “Earth’s final frontier” — the oceans — are becoming vast watery graveyards for a huge diversity of marine lifeforms, and in fact a 2006 paper in Science predicts that there could be virtually no more wild-caught seafood by 2048.

Everywhere one looks, the biosphere is wilting — and a single bipedal species with large brains and opposable thumbs is almost entirely responsible for this worsening plight. If humanity continues to prune back the Tree of Life with reckless abandon, we could be forced to confront a global disaster of truly unprecedented proportions. Along these lines, a 2012 article published in Nature and authored by over twenty scientists claims that humanity could be teetering on the brink of a catastrophic, irreversible collapse of the global ecosystem. According to the paper, there could be “tipping points” — also called “critical thresholds” — lurking in the environment that, once crossed, could initiate radical and sudden changes in the biosphere. Thus, an event of this sort could be preceded by little or no warning: everything might look more or less okay, until the ecosystem is suddenly in ruins.

We must, moving forward, never forget that just as we’re minds embodied, so too are we bodies environed, meaning that if the environment implodes under the weight of civilization, then civilization itself is doomed. While the threat of nuclear weapons deserves serious attention from political leaders and academics, as the Bulletin correctly observes, it’s even more imperative that we focus on the broader “contextual problems” that could inflate the overall probability of wars and terrorism in the future. Climate change and biodiversity loss are both conflict multipliers of precisely this sort, and each is a contributing factor that’s exacerbating the other. If we fail to make these threats a top priority in 2016, the likelihood of nuclear weapons — or some other form of emerging technology, including biotechnology and artificial intelligence — being used in the future will only increase.

Perhaps there’s still time to avert the sixth mass extinction or a sudden collapse of the global ecosystem. But time is running out — the doomsday clock is ticking.

This article borrow from my forthcoming book, The End: What Science and Religion Tell Us About the Apocalypse (Pitchstone Publishing).