Most of us have figured out by now that we are toast: Humanity will be wiped out by an asteroid, supernova, massive volcanic eruptions, global axis shift, some untreatable virus, nuclear war or climate change. Our sun is going supernova. We've seen the disaster movies, read the books and laughed at the cartoons.

But how quickly?

University of Arizona emeritus natural resources professor Guy McPherson, author of Extinction Dialogs: How to Live with Death in Mind, which he co-authored with Carolyn Baker, recently spoke at a Unitarian Universalist Church in Eugene, Oregon, offering dire, even shocking predictions.

In his talk, McPherson figures the sixth extinction in Earth's geologic history is already under way. We could see massive die-offs of humans and other species in as little as 18 months, and humanity has at best 10 to 20 years. "I could be wrong," he admits.

McPherson accuses climate scientists of "malpractice" for not being candid with the public about "our 99 percent certainty of death."

"There is no expiration date stamped on us, but we have triggered events that will lead to our extinction in the not-too-distant future," he says.

"Near-term human extinction" even has an acronym, NTHE, and McPherson is certainly not the first scientist or science writer to say we've damaged our ecosystem too much to fix it. The perfect storm of overpopulation, industrialization, pollution, deforestation, monocrops and pesticides, invasive species, urban sprawl, overfishing, warfare, reliance on fossil fuels, ignorance and corruption (and accompanying bad public policy) have had scientists waving distress flags for decades, even before Rachel Carson's Silent Spring of 1960.

The warnings have been ignored or ridiculed at the international, national, state and even local level, thanks in part to a well-funded, right-wing campaign representing the short-term interests of heavy industry, mining and fossil fuel corporations. A growing number of Americans, a record 40 percent, think the dangers of climate change are exaggerated, according to Gallup polling in recent years.

President Obama has helped Democrats wake up to the seriousness of climate change, but 68 percent of Republicans believe the threat is non-existent or overblown. Science is playing second fiddle to politics.

McPherson is correct that few climate scientists are talking about imminent human extinction, but is it a matter of professional "malpractice" or is the scientific community simply less inclined to radical extrapolation for fear of losing credibility (and grants)? Although McPherson is a scientist, he's not a climate scientist doing field research.

Phil Mote, director of the Oregon Climate Change Research Institute at Oregon State University, is skeptical of McPherson's predictions: "I've been connected to national and international assessments of the state of the science of climate change, and although my colleagues and I are generally very concerned about what challenges climate change is bringing to humankind, no expert that I have read has used language like 'extinction of the human race.' I refer of course to the Intergovernmental Panel on Climate Change, U.S. National Climate Assessment and various U.S. National Academy of Sciences reports."

Mote is involved with the IPCC, which won the Nobel Prize in 2007 along with Al Gore for their "efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change."

Elizabeth Kolbert, author of the Pulitzer Prize-winning The Sixth Extinction, says, "What is clear, and what is beyond dispute, is that we are living in a time of very, very elevated extinction rates, on the order that you would see in a mass extinction, though a mass extinction might take many thousands of years to play out."

What do local climate change activists think about McPherson and his predictions? "I can appreciate the sledgehammer—especially when people with great influence do great harm," says Delaney Pearson of the 350 Eugene Leadership Team. "But his claim that we have no chance to change anything for the better—no matter what we do—feels like surrender."

Pearson continues: "I certainly don't think our work is a waste of time, and I'm more than happy to keep on talking and writing and, yes, tweeting about all the ways we might change the world for the better." She says, "For now, I choose Bill McKibben and all the people around me and around the world working so hard to turn this crisis into an amazing opportunity for good."

McKibben is a leading voice for climate action, and he recognizes the threat of global climate catastrophe, but his optimistic book Hope, Human and Wild focuses on the many inventive solutions supporting sustainability that he has found around the world.

International journalist and author Dahr Jamail wrote on the nonprofit news site Truth-out.org in December 2014 that "coal will likely overtake oil as the dominant energy source by 2017, and without a major shift away from coal, average global temperatures could rise by 6 degrees Celsius by 2050, leading to devastating climate change. This is dramatically worse than even the dire predictions from the Intergovernmental Panel on Climate Change, which predicts at least a 5-degree Celsius increase by 2100 as its worst-case scenario."

Jamail adds, "There is nothing to indicate in the political or corporate world that there will be anything like a major shift in policy aimed at dramatically mitigating runaway anthropogenic [human-caused] climate disruption."

Mary DeMocker of 350 Eugene was in the front row at McPherson's talk, and she says: "Until James Hansen or a lot of scientists of his caliber and expertise call it game over, I'm fighting to win and holding onto the thread of hope he offers that it's a closing window, but it's a window nonetheless, and it's still open."

DeMocker adds that McPherson "never mentioned that you can pull carbon out of the atmosphere and reduce the 400 ppm to a livable amount. And in that he's doing a profound disservice. It can be done, 7 percent yearly reduction."

The rationale for extinction

What does McPherson base his NTHE predictions on? In his lectures and on his blog Nature Bats Last (see guymcpherson.com), he says, "I've been accused of having no hope, and that's true." Environmental scientists tend to specialize, and McPherson has collected their published research from around the world. He cites and documents "irreversible, self-reinforcing feedback loops" from hundreds of scientific studies.

He admits to "cherry picking" his data, but "no matter how dire the situation becomes, it only gets worse when I check the latest reports." He was so convinced by the evidence that he left his academic career behind and became a certified grief counselor to help people through their final days.

Even the relatively staid IPCC has warned of such a scenario: "The possibility of abrupt climate change and/or abrupt changes in the Earth system triggered by climate change, with potentially catastrophic consequences, cannot be ruled out. Positive feedback from warming may cause the release of carbon or methane from the terrestrial biosphere and oceans."

Here are a few of McPherson's conclusions. If this is all too depressing, skip to the "What We Can Do About It?" sidebar.

• The Arctic ice cap is breaking up for the first time in recorded history. "An ice-free Arctic could be this year, in September," McPherson says, "and this could lead to a burst of methane at any time" from the shallow Arctic seabed. An ice-free Arctic could also lead to large-scale drilling for oil and gas, which would exacerbate our overdependence on fossil fuels.

• Methane, a greenhouse gas, is also trapped in permafrost and peat bogs in boreal forests. Warming would release vast volumes of methane into the atmosphere. Giant "methane blowholes" are appearing in Siberia. Thawed peat can also catch fire and smolder for years, releasing carbon and covering ice fields with soot. The "dark ice" in turn absorbs sunlight and hastens melting.

• Earth's soils contain countless trillions of microorganisms that hold about half the sequestered carbon on the planet. Soil warming will release carbon dioxide.

• Rising atmospheric carbon dioxide gets a lot of attention (think Al Gore's An Inconvenient Truth), but it's only one factor in rising temperatures. Ozone doesn't get as much attention, but atmospheric ozone is blamed for forest dieback, which in turn reduces carbon sequestration.

• Heat by itself will not kill humanity, he says, but hot summers will lead to crop failures and mass migration. "We are clever but we cannot live without habitat, at least not for long." Countries closer to the poles, he says, don't have fertile soils and can't grow nearly enough food to feed billions of people.

• Lack of fresh water is already a huge problem worldwide, and it will get much, much worse. Water shortages will stifle agriculture (think dust bowls and desertification) and seriously hamper business, industry and drinking water supplies. Desalination is expensive and energy-intensive with our current technology.

• The world's 443 nuclear power plants could melt down due to lack of cooling water, blanketing the planet with toxic radiation. It takes decades and many millions of dollars to decontaminate and decommission a single nuclear plant, and more than 60 new nuclear reactors are being built today.

• Rising sea levels will inundate cities and lowlands, displacing more than one billion people and flooding low-elevation farmland with saltwater. Coastal erosion will also destroy plant habitat and release carbon dioxide. A global hike in temperatures of just 1-2 degrees Celsius could raise sea levels by 20 feet, according to a study of the geologic record just released last week by OSU scholars Anders Carlson and Peter Clark.

• Our oceans and their prevailing currents are in flux for a variety of reasons, and jellyfish could take over, destroying the food chain for the rest of sea life. Billions of people rely on seafood and seaweed as diet staples.

• El Niño, a natural cycle of ocean warming, can exacerbate both flooding and drought, along with storm intensity, wildfires and other factors in the "vicious cycle" of climate change.

• Water vapor in the troposphere increases with warming and in turn "absorbs more heat and further raises the Earth's temperature," McPherson reports.

• Our planet in relationship to the sun is already at the "inner edge of the habitable zone, and lies within 1 percent of inhabitability," McPherson says. "A minor change in Earth's atmosphere removes human habitat." None of our neighboring planets can support human life on any significant scale.

Contrary perspectives

Noted Australian science writer Geoffrey Chia, M.D., writes in The Canadian Daily online, "I have learned a great deal from the writings and presentations of Dr. Guy McPherson. However, I do not agree with all of his conclusions or views."

"Everyone gets things wrong," Chia says. "It is impossible to conceive of any credible scenario in which the mass die-off of billions of people will not occur in the century. Mass culling is guaranteed. ... Is it, however, possible that a small number of humans may be able to survive the next couple of thousand years, given adequate preparations in certain geographical pockets, until the overall global climate becomes more conducive to humans?"

Chia figures planetary temperatures will "eventually cool in the long term in the absence of large numbers of humans," and biosequestration of carbon will resume.

Hydrologist and science writer Scott K. Johnson is more skeptical and writes on his Fractal Planet blog: "It takes careful examination of McPherson's references, and a familiarity with the present state of climate science, to uncover that his claims aren't scientific at all."

Johnson says McPherson "just latches onto anything that sounds scary," he is "especially fast and loose with timeframes," and "his argument fundamentally reduces to 'positive feedbacks exist, ergo extinction.'"

Some final thoughts on extinction

"After his talk I went home and read his book—whole—gobbled it up nearly," says Jungian psychoanalyst Jennifer Gordon of 350 Eugene. "I wanted to ask him to say more about 'It depends on the political will of the people,' the only hopeful thing I heard him say."

Delaney Pearson of 350 Eugene says, "To McPherson I would also argue that we (the privileged first world) have debts to pay, and it's not good enough to just give up and 'face the truth' while billions of people continue to experience the worst effects of climate change. This is about justice—on all levels. The animals and trees, rivers, oceans and skies, children and new babies everywhere need and deserve our attention."

Laurie Granger of the Raging Grannies and 350 Eugene says, "We're all living in this moment. In every forum we share our concerns and knowledge and passionately try to make a difference. As we're on this path, there's no room for doom and gloom."

Laurie Ehlhardt of 350 Eugene says Pope Francis departs from McPherson's outlook concerning where we go from here. She quotes his recent encyclical: "Many things have to change course, but it is we human beings above all who need to change. A great cultural, spiritual and educational challenge stands before us, and it will demand that we set out on the long path of renewal."

This story was originally published in the Eugene Weekly. Ted Taylor has been editor-in-chief at Eugene Weekly since 1998. He is a University of Oregon journalism grad with 30 years experience in daily and weekly newspaper writing, editing and managing.

What can we do about it?

Guy McPherson quotes Edward Abbey, saying, "Action is the antidote to despair," and encourages activists to go down fighting. Giving up and being depressed accomplishes nothing and is no way to die, or live for that matter. He advocates for "the simple life," echoing the idea that we should "live simply so that others may simply live."

"Do what you love to do and live life by striving for excellence every day," he says. "Treat people with dignity and compassion, and think about how you are going to live and not about how you are going to die."

He says to "not worry about the jerks in your life, the guy in the Hummer who just cut you off. He will die, too."

Knowing we are all going to die soon can also be liberating, McPherson says. No more worries about that retirement plan, that bucket list, how to pay for the grandkids' education, etc. Money, in fact, will be worthless when the world economy collapses. Even gold and silver will lose their value when they can no longer buy food, water and shelter.

Worried about your personal legacy? It takes about 10 million years to recover from mass extinction. The next evolution of Homo sapiens will have no knowledge of you, Beethoven, Donald Trump or Kim Kardashian's butt.

Groups of people who have accepted abrupt climate change (ABC, another new acronym) are forming, and a website is up at onlyloveremains.org. The website offers low-cost workshops and reads, "You've come to grips with near-term human extinction. It's a lonely conclusion, one that interferes with many relationships. You want somebody with whom to discuss the most important topic in the history of our species. It seems most of your friends and family are in denial. Now what?"