The Scientific Case for NTHE (Near-Term Human Extinction): Reviewing the Evidence
Direct mortal effects of climate change include heat waves, which have already caused thousands of human deaths by a combination of heat and humidity (wet-bulb temperature >35°C, such that the human body is physically unable to cool itself with perspiration).
Intermediate causes of death (between direct and indirect) involve crop failures, droughts, flooding, extreme weather, wildfires, and rising seas.
(see)
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Extinction is the complete disappearance of a species from Earth. The predominant cause of extinction is loss of habitat.
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The risk of human extinction has been dangerously underexplored.
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Is near-term human extinction (NTHE) really possible?
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TL;DR:
It’s more likely than you might be willing to accept.
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How soon is “near-term”?
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Some people have predicted the complete extinction of the human species as early as 2026 (see, see).
Others have made bold proclamations that there will not be a single human alive by 2100 (see).
Still others refuse to put a specific date on it, preferring to give a range, such as the prediction that almost all mammalian life will be extinguished between now (2024 at the time of writing) and 2050 (see).
Whether it’s two years from now or 76 years from now, if we condense the age of the earth (4.5 billion years) into a single calendar year, that’s the difference between 0.000007 seconds and 0.0005 seconds out of the year.
If we want to be more generous and instead condense the age of the human species (300,000 years) into a single calendar year, that’s the difference between 3 minutes and 2 hours out of the year.
That’s a far cry away from the speculations of some scientists that claim humans will persist for another 250 million years (see). If this were actually the case, then out of one year, that would put us at a sprawling 364 days, 13 hours and 30 minutes away from human extinction, freshly nestled in the spring infancy of our species’ lifetime. This sounds incredibly hopeful — until you learn that this calculation only works when the effects of fossil fuel–caused climate change are completely ignored in the models used.
So how soon is near-term?
Depending on the timeframe you’re taking, out of one year it’s either
- the last few fractions of a second to midnight,
- the last 3 minutes to midnight, or
- (in the rosiest view) it’s 10pm, dinner’s over, everybody’s gone home, and you’re staring down the last two hours until it’s lights out. Two small hours to sit, and sigh, and reflect on everything that’s come to pass throughout this year.
Is there any scientific research supporting the case for near-term human extinction?
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First, let us clarify what NTHE is not.
It is not the possibility of a random freak occurrence that could come out of nowhere and annihilate humanity.
- NTHE is not a risk because of things that could eradicate humanity if they occurred, but in their absence humanity will continue trucking along as normal.
- The threat of NTHE is not something that might happen in the future because of bad luck or bad future decisions (like nuclear war).
- It is not something that might have happened at any time in the past because of a random freak event (like an asteroid impact).
That is not where the threat of NTHE comes from. When we talk about NTHE, we’re not talking about something that comes out of nowhere and wipes out the species. Because, it doesn’t come out of nowhere.
NTHE is simply one byproduct of the trajectory that the planet’s climate is already currently locked into.
Let’s review the evidence.
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Here’s what we know for certain:
1.
Climate change is occurring today faster than it did during
- A) the mass extinction event that wiped out the dinosaurs (see), and
- B) the only mass extinction event that wiped out 90% of life on Earth (see, see).
In fact, it’s occurring faster than it ever has in planetary history (see).
2.
Climate change is accelerating exponentially (see).
- Exponential change is fast (see).
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Climate change today is
4.
We are entering the climate conditions of an entirely different geological epoch by 2030 (see).
- The last time this level of change occurred in the planet’s history, it took 3 million years (see).
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In planetary history, whenever global temperatures change too quickly, mass extinction events predictably occur (see).
- These mass extinction events consistently wipe out complex species at the top of the food pyramid (see, see, see).
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It has been documented by scientists that we are already in the midst of the ongoing latest mass extinction event, horrifyingly described as planetary biological annihilation (see, see, see).
7.
Acute biosphere collapse (or, “abrupt ecological disruption” causing a “catastrophic loss of global biodiversity”) has already begun before 2030 (see).
8.
No vertebrate (see, see) or mammal (see) species can adapt fast enough to the rate of environmental change (see) underway at present.
9.
The climate has crossed a level of greenhouse gas concentration (>500ppm CO₂eq) that commits us to a global temperature (>2°C above pre-industrial levels) that has locked us into triggering tipping points (see, see).
- This means that we have functionally already triggered all of the climate tipping points (see).
- When these tipping points are triggered, equilibrium is not reached until the Earth is 10°C hotter (see).
- 5–6°C above pre-industrial is most likely more than sufficient to guarantee human extinction, and possibly ensure the extinction of all life on Earth (see, see, see).
10.
We are already witnessing unlivable wet-bulb temperatures emerging (see, see) at our current global temperature of 2°C above the pre-industrial baseline (see, see, see, see).
- When these temperatures become consistent and widespread across the globe on the exponential road to 10°C, we will see an explosive rise in the area of the planet’s surface that is unsurvivable by humans (see).
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These are things we know for certain.
Where we are — a snapshot:
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- The Earth is suitable for life as it has currently evolved only when the atmosphere has a greenhouse gas concentration of ≤350ppm CO₂-equivalent (see), and we are above 560ppm CO₂eq already (see, see).·
- The Earth is only safe for humans below 1.5°C (see), and we have crossed 1.5°C already (see, see, see, see, see, see, see).
- The Earth is uninhabitable past 2°C, precisely because once we cross 2°C, we set off at least a dozen runaway tipping points that take us uncontrollably to a collapsing biosphere on an Earth that is too hot for humans to live on (see, see, see, see, see).
- We have even crossed 2°C already (see, see, see, see, see, see, see) precisely because of the concentration of CO₂eq already present in the atmosphere (see, see).
- Therefore, we have already functionally triggered all known climate tipping points (see).
- There is no plan in place to halt carbon emissions (see), nor is there any magic technology to reduce current atmospheric greenhouse gas concentrations (see, see).
- Even if we did halt carbon emissions, the resultant cessation of aerosol forcing from industrial activity would trigger a loss of aerosol masking globally, causing the temperature to drastically rise due to the incoming solar radiation no longer being reflected by an atmospheric blanket of industrial pollutants (see). This fatal quandary has been termed the McPherson Paradox (see, see).
- As such, there is no reversing our global heating commitment, or avoiding the unstoppable effects of tipping points.
- We are already locked into, and being fast-tracked to, an uninhabitable planet — Hothouse Earth (see, see, see).
Uninhabitable means uninhabitable.
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Sudden events likely to cause human extinction
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Many people hold fast to the expectation that collapse will be a slow, gradual process of declining living standards, not a sudden event that terminates civilization (let alone the entire species).
However, this may be due to unconscious limitations in our evolutionary cognition that inhibit our ability to recognize the unfathomable scale and extent of the hyperobject that is the human species’ impact on our planet due to the megamachine we have created and set loose, both on the world and on ourselves.
There is not a square metre of this planet that is not polluted with microplastics, from the clouds in the sky to untouched columns deep in the earth; macabrely, they can even be found in our brains, in our blood, and in our placentas. Most of the animal biomass on the planet is either us or the select few animals we raise as cattle and process through factories as though they were merely machine parts. In just 312 years, since the invention of the first steam engine, we have accelerated the Earth through a geological transition that should have taken 3 million years. In order to achieve this geologically unprecedented feat, we burned through 400 million years of ancient sunlight, itself a profound and tremendous phenomenon resulting from a collaboration between the sun and the earth’s biosphere, in just three centuries. Human impact on the climate has even changed how time flows on this planet.
The result of these incredible and terrifying achievements is that, at this stage of development in human technology, and at the sheer scale and extent to which we have tampered with the biosphere, collapse and extinction are two sides of the same coin.
Acknowledging this fact is what one writer refers to as “getting real about collapse/extinction,” or grace.
Understandably, these phenomena are not easily processed by the individual human mind. Neither is it easy to accept just how delicate industrial civilization is, or to come to terms with the fact that just one major event could effectively eradicate the now fatally precarious conditions of human habitat on this planet and swiftly seal our fate into extinction.
Let us consider a few of those events now.
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1.
Loss of Aerosol Masking
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Recent temperature spikes have been linked to the reduction of sulphur content in the aerosol emissions of cargo ships (see).
Industrial activity emits atmosphere-polluting aerosols that have the unintended consequence of reflecting incoming solar radiation, therefore preventing sunlight from striking the Earth’s surface and heating the planet.
This phenomenon, alternately referred to as global dimming or the aerosol masking effect, was observed when planes were grounded nationwide in the United States on 11 September 2001 (see), and again more recently when the 2020 pandemic caused industrial activity to temporarily stagnate worldwide (see).
Aerosols emitted by industrial activity mask up to 155% of temperatures over land and 33% over the oceans (see).
A reduction of as little as 35% of industrial activity could cause a global temperature spike of 1°C (see).
It takes only five days for aerosols to fall out of the atmosphere (see, see).
Complete cessation of aerosol forcing could lead to a global average temperature rise of 55% within a few days (see).
On top of the current global temperature of 2°C above the pre-industrial baseline, this would bring the planet to 3.1°C.
Because the masking effect is amplified over land, this would bring land temperatures to 4.7°C. All in less than a week.
The double-bind that the aerosol masking effect puts us in, wherein both stopping and continuing carbon emissions accelerates planetary heating, has been called our Faustian bargain, or the McPherson Paradox (see, see).
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The Blue Ocean Event
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The Arctic ice cap is rapidly melting, and very soon there will be below one million square kilometres of ice left on the North Pole. When this happens, the Arctic will be considered to be effectively ice-free. “Once dark water replaces brilliant ice, Earth could warm substantially” (see). This is known as the Blue Ocean Event (BOE) (see).
Losing the remaining Arctic sea ice and its ability to reflect incoming solar energy would be equivalent to adding one trillion tons of CO₂ to the atmosphere, equivalent to roughly 25 years of global CO₂ emissions at current rates (see).
It is important to note that this is due to the reflectivity of ice alone. It does not account for any further warming processes that may be triggered by the BOE, such as methane eruptions, carbon dioxide venting, cloud-formation feedback, or atmospheric and ocean current disruptions.
As long as it is frozen solid, ice maintains a temperature of 0°C regardless of the heat energy it is exposed to, up to a limit. Once the Arctic ice fully melts, all of the energy going into melting that frozen ice will instead be absorbed by the liquid water, causing a dramatic spike in temperature.
The amount of energy needed to melt one kilogram of ice (334 kJ), when applied to the same quantity of liquid water at zero degrees, will raise that water’s temperature from 0°C to 79.8°C (see).
Arctic sea ice loss is irreversible (see). Once the BOE occurs, temperatures will be fastforwarded by 25 years and will only continue to rise at breakneck speed.
Half of all emissions from fossil fuels dating back to the 1700s have been produced in the last ~30 years (see, see). That means that the BOE would increase global temperatures to a degree equivalent to the effect of all the fossil fuel burning that occurred in the 278 years between 1712 and 1990, a quantity itself equivalent to the emissions made between 1990 and 2020.
One scientist is quoted as saying the BOE will “crush humanity like a bug” (see, see, see).
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The Methane Burp
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Underneath a layer of already melting permafrost in the East Siberian Arctic Shelf (ESAS), there are extreme concentrations of methane trapped in shallow seabed sediments, totalling an estimate of 1400 gigatonnes (Gt) of carbon. Since 2008, it has been considered highly possible for the ESAS to abruptly release a 50 Gt methane eruption at any time, resulting in a twelve-fold increase in total atmospheric methane content (see, see).
Despite it making up only 16% of total industrial greenhouse gas emissions, compared to CO₂’s 76% (see), methane is responsible for 25% of total global heating, due to the fact that it traps more heat in the atmosphere per molecule than CO₂ and is 80 times more potent than CO₂ for 20 years after its emission (see).
It’s important to note that the 50 Gt ESAS eruption is not contingent on the presence of an ice-free Arctic. It can happen at any time even while the Arctic is still ice-capped. However, once the BOE does occur, this eruption — and far greater ones — becomes significantly more likely. As such methane bursts become more numerous, they will rapidly transition the planet to 4°C and (due to the mounting effects of tipping points) beyond (see).
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Even in the absence of these sudden events, the combined effects of the exponential rise of global heating, paired with the chaotic and uncontrollable momentum of cascading positive feedback loops in the climate caused by crossing irreversible tipping points, are already driving global temperatures to a difference of geological proportions before the end of this decade.
As such, specific sudden events may not even be required to trigger sudden loss of habitat for Homo sapiens and seal the fate of human extinction.
Scientists’ final warnings fall on deaf ears
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- In 1965, the President of the American Petroleum Institute, citing a report made by the Science Advisory Committee to the President of the United States of America, announced at an oil industry conference that “time is running out” to “save the world’s people from the catastrophic consequence of pollution” (see).
We did not move to save the world’s people from the catastrophic consequences of pollution.
- Between 1982 and 1989, a group of senators and scientists including Carl Sagan, James Hansen and Al Gore testified to the United States government about the reality and the dangers of greenhouse effect, warning that national and international action was required to prevent CO₂ pollution from destabilizing the Earth’s climate (see, see).
We did not take action, national or international, to prevent climate destabilization from CO₂ pollution.
- In 1989, the Director of the United Nations Environment Program (UNEP) New York office warned that there were only 10 years left to solve the greenhouse effect before it would go beyond human control (see, see).
We did not mitigate, let alone solve, the greenhouse effect.
- In 2006, climate scientist and then Director of the NASA Goddard Institute for Space Studies James Hansen stated that, “I think we have less than a decade to avoid passing what I call ‘point of no return.’ I think we have to keep global warming less than one degree Celsius, or we’re going to get very bad effects” (see, see).
We did not keep global warming to less than 1°C.
- In 2018, the United Nations Secretary General announced that the world had less than two years to avoid runaway climate change (see). He implored global leaders to change course by 2020.
We did not change course.
- In 2021, scientists warned that humans have caused unprecedented and irreversible change to the climate (see), with “only rapid and drastic reductions in greenhouse gases” able to “prevent climate breakdown.”
We did not implement any reductions in greenhouse gases.
- In 2022, scientists told the world it’s “now or never” to limit warming to 1.5°C and stave off the climate crisis via deep emissions reductions (see).
We did not cease emissions or limit warming to 1.5°C.
- In 2023, scientists issued their final warning on the climate crisis: “Act now or it’s too late” (see).
We did not act.
- 2024, World Meteorological Organization: Red Alert (see).
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Now, with all of this discussion in mind,
What reasonable extrapolation can be drawn from this information?
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· · · Final note:
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Don’t expect to hear about this in any kind of official announcement.
Scientists will likely never officially declare imminent human extinction with 100% certainty.
The closest we’ll probably get is 15,000 scientists from 184 countries warning that life on Earth is under siege (see), or telling us that we have mutilated the Tree of Life (see) and that we are on the eve of destruction (see).
Waiting for mainstream science and the majority of scientists (i.e. a massive, slow-moving, risk-averse and disparate body of professionals operating under extreme financial, political, and social pressure (see) to underexplore (see) and underreport the significant threats of fossil fuel combustion to the ability to sustain human life on Earth) to deliver a unified message with total confidence is both inadvisable and not necessary to connect the dots.
From the European Strategy and Policy Analysis System (ESPAS),
An increase of 1.5 degrees is the maximum the planet can tolerate; should temperatures increase further beyond 2030, we will face . . . at worst, the extinction of humankind altogether.
(see)
If 1.5°C spells the potential for the extinction of humankind altogether, then the exponential temperature increase caused by tipping points within less than a decade will rapidly bring us much closer to that possibility, as well as dramatically increase the likelihood of its coming to fruition.
Science does not and has never operated by the publication of definitive claims expressed with complete certainty.
But we don’t need to wait until a coroner pronounces us dead to accept that our terminal illness is, indeed, terminal.
This is where we are.
We are locked into a trajectory of planetary annihilation and show no signs of slowing (see).
One final glimmer of hope?
A rogue, seemingly desert Earth wandering across the Universe could still have some tiny chance of blooming again under some lucky — and unlikely — circumstances.
(see)
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For an unofficial companion piece, please see Michael Dowd’s Main Drivers of Collapse, Ecocide, and Likely NTHE.
Image Credits:
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