The Fate of Earth and Destiny of
Life on this Planet
by blogger lim ju boo alias: lin ru wu (林 如 武)
Previously I have written a few articles
on:
Our Dilemma of Over Population
published on Monday, August 1, 2022,
here:
https://scientificlogic.blogspot.com/2022/08/our-dilemma-of-over-population.html
The Dangers and Consequences of
Human Overpopulation (Part II)
https://scientificlogic.blogspot.com/search?q=the+fate+of+humanity+part+1
https://scientificlogic.blogspot.com/search?q=fate+of+humanity+overpopulation++1
Introduction:
Having studied postdoctoral astronomy at Oxford, and how life came into existence on Earth at Cambridge, I am now wondering how long this earth, its civilizations, including all life on earth will last, barring a premature cosmic catastrophe, Earth has about 5 to 7.5 billion years left before being engulfed by the sun.
However, the planet will likely become uninhabitable for complex life much sooner, possibly within the next billion years, due to the sun's natural evolution. Short-term risks to habitability (decades to millennia) Though on a much shorter timescale, certain terrestrial and celestial events could trigger a mass extinction event such as Human activity: Issues such as climate change, pandemics, nuclear war, and unchecked technological advances (e.g., artificial intelligence) pose risks to human civilization and other life. Some models predict a "catastrophic collapse in human population" within decades if resource consumption and deforestation continue at present rates. Super volcanoes: On average, a super volcano eruption occurs every 100,000 years, capable of generating enough fragmented material to cause a global environmental catastrophe. Asteroid impacts: While rare, a large enough asteroid or comet impact could cause an extinction-level event. The mean time between major impacts is estimated to be at least 100 million years. Nearby supernovae: A stellar explosion within 100 light-years of Earth could contaminate the planet with radiation, potentially depleting the ozone layer for centuries and impacting the biosphere. Mid-term changes (hundreds of millions of years) Over a longer period, several natural and predictable events will fundamentally alter Earth's environment:
Extinction of plants: In about 600 million years, the sun's increasing luminosity will reduce atmospheric carbon dioxide below the level needed for most plants to survive. The extinction of plants would trigger the collapse of most animal life. Runaway greenhouse effect: In roughly one billion years, the sun will be 10% brighter, triggering a "moist greenhouse" effect that causes the oceans to evaporate. This will eliminate Earth's water, end plate tectonics, and trigger a runaway greenhouse effect, transforming Earth into an extreme version of present-day Venus. Loss of magnetosphere: After 2 to 3 billion years, the planet's core may solidify, causing the magnetic dynamo to fail. The loss of the magnetosphere would lead to the rapid erosion of Earth's atmosphere by solar winds. A new supercontinent: Plate tectonics will continue to reshape the planet, and in 250 to 350 million years, Earth's continents will likely merge into a new supercontinent, altering weather patterns and ecosystems. Ultimate end (billions of years from now) The final fate of the planet is tied to the death of our sun: The sun's red giant phase: In about 5 to 7.5 billion years, the sun will exhaust the hydrogen fuel in its core and expand into a red giant star, growing so large that it will engulf Mercury and Venus and potentially Earth.
Vaporization: The intense heat from the expanding sun will cause Earth's oceans to boil away and its surface to melt, even if the planet's orbit expands enough to avoid being fully absorbed. Swallowed by the sun: According to some calculations, the expanding sun will likely engulf Earth in about 7.59 billion years. Earth's orbit would decay due to tidal interactions and drag from the sun's atmosphere.
Let's continue this discussion in a more detailed manner what will happen to this Earth billions of years from the present?
We live on a remarkable planet: Earth.
Earth has carried life in myriad forms for billions of years that housed complex civilizations, and given rise to consciousness capable of pondering its own fate. Yet all things evolve, including the habitability of Earth and the future of its civilizations. 7
Barring a premature cosmic
catastrophe, the story of Earth’s
longevity unfolds in three broad arcs:
the short-term risks (decades to
millennia), the mid-term
changes (hundreds of millions of years),
and the ultimate destiny (billions of
years). Each arc carries its own perils,
possibilities, and profound lessons for
our civilization today.
Short-Term Risks: the ticking clocks
Humanity and the biosphere face urgent challenges that, unlike the slow march of stellar evolution, operate on timescales meaningful for our civilization, centuries, decades, even decades to centuries. Several of the most critical events leading to our demise are:
Human activity: Climate change, biodiversity loss, pandemics, nuclear war, runaway technological risks (for example from advanced artificial intelligence) all pose existential threats to human civilization and to other life. The scenario of “catastrophic collapse in human population” is not as far-fetched as once thought if resource consumption, deforestation, ecosystem collapse and social breakdown continue unabated.
Super-volcanoes & natural disasters: A super-volcanic eruption (on average perhaps every ~100,000 years) could spew enough debris and aerosols into the atmosphere to trigger years of global cooling, crop failures and mass extinctions.
Asteroid / comet impacts: While rare in human timescales, an impact of sufficiently large size (tens of kilometers) could devastate complex life on Earth. Estimates put the mean interval between extinction-level impacts at tens to hundreds of millions of years.
Nearby supernovae / gamma‐ray bursts / cosmic threats: A stellar explosion or intense cosmic radiation within perhaps 100 light-years could strip away the ozone layer, increase surface radiation, compromise the biosphere and set off cascading extinctions.
The lesson: While the great cosmic clocks will ultimately rule Earth’s fate, our civilization must navigate far more immediate perils. In fact, the short-term risks may be our window of responsibility. The investment we make now in resilience, sustainability, cooperation, and technology will determine if we thrive long enough to witness the latter epochs.
Mid-Term Changes: the slow death of a biosphere
Even if we navigate the immediate perils, Earth will not remain hospitable to complex life forever. The long arc of cosmic and geological timescales imposes vulnerabilities that no civilization can escape, though advanced technology may delay or adapt. Some key milestones:
In roughly ~600 million years, the rising luminosity of the Sun will have drawn down the atmospheric carbon dioxide via enhanced silicate weathering and the carbonate-silicate cycle to levels below what many plants (especially C₃ plants) require for photosynthesis. As the biosphere’s green foundation collapses, animal life will face severe stress. Wikipedia+2Treehugger+2
Around ~1 billion years from now, the Sun, currently increasing its luminosity at about 1% every ~110 million years or ~10% over a billion years. OUP Academic+2AGU Publications+2 At that point Earth’s surface temperatures may reach ~45-50 °C (or higher) in many regions, the oceans begin to evaporate, triggering a “moist greenhouse” or even full runaway greenhouse effect, steam-blanketing the planet, shutting down plate tectonics and the carbon cycle, transforming Earth into a world more like a scorched desert. Wikipedia+2Wikipedia+2
Beyond that, in ~2-3 billion years, the core may begin to cool and solidify, causing the geodynamo that generates Earth’s magnetosphere to weaken or fail. Without a magnetic field, solar wind may strip the atmosphere, further robbing the planet of habitability. Wikipedia
Over hundreds of millions of years, plate tectonics will continue to reshape the continents; a new supercontinent may form in ~250-350 million years, altering climate and ecosystems drastically.
Even before the final demise, many life forms will vanish; most complex life will fade, leaving only hardy microbial refuges living in deep niches. arXiv
In effect: the day when Earth is habitable for complex, conscious life like ours is far shorter than the total lifespan of the planet. Some studies suggest the oxygenated atmosphere and complex biosphere may have only about ~1 billion years left. Sky at Night Magazine+1
Oxygen levels will drop drastically as the
Sun becomes brighter and hotter. All
aerobic life including us becomes
impossible. Photosynthesis too will
decline as all plants die as the Sun
becomes brighter and hotter.
Ultimate End: the red giant catastrophe
At the grandest scale, billions of years hence, the fate of Earth and
its civilization is bound to the fate of the star that sustains it - the Sun.
In ~5 billion years, the Sun will exhaust its core hydrogen fuel and begin its red-giant phase, expanding outward, possibly engulfing Mercury and Venus, and quite possibly Earth as well. Astronomy+1
Even if Earth’s orbit expands or tidal interactions delay its engulfment, the intense heat will boil the oceans, melt the crust, and render the planet utterly inhospitable to life. Some models place Earth’s complete destruction in about ~7-7.5 billion years. Wikipedia+1
After the red-giant phase, the Sun will shed its outer layers, become a white dwarf, and the Solar System will drift into a cold, long twilit existence. planetplanet.net+1
Thus, even in the absence of a premature catastrophe, Earth’s habitable window is finite. Complex life has a terminal clock.
Reflections and human significance
Given these layered timelines, here are a few of my own thoughts, drawing together the science and our human predicament:
We are in the middle innings of Earth’s habitable era. While the planet isn’t about to die tomorrow, the clock of habitability has been ticking for billions of years and will continue for perhaps a billion more in a rich biosphere sense. That’s still plenty of time - thousands of generations, to act wisely, but it is also a reminder that nothing lasts forever.
The fragility of complex life. The most striking insight is that complex life (animals, forests, human civilization) will likely vanish long before the planet itself is physically destroyed. The foundations of life, plants and photosynthesis, are vulnerable to changes in solar luminosity and CO₂ draw-down. Thus, the bigger threat isn’t just “the Sun will engulf us in 5 billion years,” but “the biosphere will collapse / life will simplify a billion years or more before that.”
Human agency and urgency. On the short term, the risks we face (climate change, technology, global war, pandemics) are immediate and actionable. The long-term eventualities do not negate the need to act now, in fact they amplify the responsibility. If civilization is to span into the mid-term epochs, we must build resilience, sustainable systems, global cooperation, and possibly expand beyond the Earth.
Civilization as a bridge to the future. If humanity (or our successor species / technologies) aspire to persist into the mid-term and perhaps witness the final chapters of Earth’s history, we must think in astronomical timescales. Even thinking about relocating our orbit, terraforming other worlds, or becoming a multi-planet species might be necessary. Indeed, some researchers propose moving Earth outward to stave off the Sun’s warming. Medium
Perspective and humility. The durations here are immense: a billion years is a long time relative to human history, but short in cosmic time. The fact that we exist now, in this “sweet spot” when complex life flourishes, is remarkable. Future beings might look back on our era as one of abundance, light, biodiversity and creativity - a blink in the planet’s lifetime.
Legacy and meaning. Knowing that the planet’s habitability is finite invites deep reflection: What kind of civilization do we want to build? What do we hope to leave behind? How do we steward Earth’s rich biosphere while we can, and what steps do we take to secure a future beyond immediate crises?
A Summary of My Vision:
Currently scientific literature supports the view that Earth has perhaps ~1 billion years or so of robust habitability for complex life (and many billions more for microbial life) before the Sun’s evolving nature extinguishes that era. Several studies reinforce that estimate: for example, the oxygen-rich atmosphere is likely to collapse in about a billion years. Sky at Night Magazine+1 The Sun’s luminosity will increase steadily, driving Earth’s climate into regimes too hot for forests, oceans, and animal life. Wikipedia+1 And ultimately, in ~5-7 billion years, the Sun will swell and likely engulf the planet. Astronomy+1
Yet while this might sound depressing, it is also empowering. Earth’s future is not predetermined on the short term by cosmic inevitability alone, our actions matter deeply. We stand at a crossroads where our civilization can either strengthen and flourish for millennia, or succumb to avoidable risks. And the longer we last, the more our choices ripple into that distant future.
References and Further Reading
1. The Future of the Earth and Solar Evolution
Schröder, K.-P. & Smith, R. C. (2008). Distant future of the Sun and Earth revisited. Monthly Notices of the Royal Astronomical Society, 386(1), 155–163.
https://doi.org/10.1111/j.1365-2966.2008.13022.x
- A classic astrophysical paper modelling how the Sun’s evolution will affect Earth’s orbit and final fate.
NASA Goddard Space Flight Center. The Life Cycle of the Sun.
https://solarsystem.nasa.gov/solar-system/sun/overview/
- Clear explanation of the Sun’s present and future stages.
Ward, P. D. & Brownlee, D. (2000). The Life and Death of Planet Earth. New York: Times Books.
- An excellent, readable book on how the biosphere and atmosphere will evolve until life ceases.
O’Malley-James, J. T. et al. (2013). Swansong biospheres: refuges for life and novel microbial biospheres on Earth’s far future. International Journal of Astrobiology, 12(2), 99–112.
https://doi.org/10.1017/S147355041200047X
2. Atmospheric and Biospheric Changes
Caldeira, K. & Kasting, J. F. (1992). The life span of the biosphere revisited. Nature, 360, 721–723.
https://doi.org/10.1038/360721a0
- Seminal study estimating how rising solar luminosity will limit habitability.
Schwieterman, E. W. et al. (2019). A limited habitable zone for complex life. The Astrophysical Journal, 878(1), 19.
https://doi.org/10.3847/1538-4357/ab1d52
- Examines how changing CO₂ and oxygen levels will shrink Earth’s habitable zone for complex organisms.
Reinhard, C. T. et al. (2021). The future lifespan of Earth’s oxygenated atmosphere. Nature Geoscience, 14, 138–142.
https://doi.org/10.1038/s41561-020-00693-2
- Predicts Earth will lose its oxygen-rich atmosphere in about a billion years.
3. Geophysical and Magnetic Evolution
Driscoll, P. E. & Bercovici, D. (2014). Divergent evolution of Earth and Venus: Influence of degassing, tectonics, and magnetic fields. Icarus, 226(2), 1447–1464.
https://doi.org/10.1016/j.icarus.2013.07.025
- Discusses why Earth may eventually lose its magnetosphere as its core cools.
Way, M. J. & Del Genio, A. D. (2020). Venusian habitable climate scenarios: Runaway greenhouse limit reconsidered. Journal of Geophysical Research: Planets, 125(5).
https://doi.org/10.1029/2019JE006276
4. Catastrophic and Near-Term Risks
National Academies of Sciences (2019). Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington D.C.: National Academies Press.
- Comprehensive report on monitoring climate and human impacts.
NASA Jet Propulsion Laboratory. Planetary Defense Coordination Office.
https://www.jpl.nasa.gov/asteroid-watch
- Official NASA resource on asteroid and comet impact monitoring.
Rampino, M. R. (2022). Cataclysms: A New Geology for the Twenty-First Century. Columbia University Press.
- Discusses asteroid impacts, super-volcanoes, and periodic mass extinctions.
5. Accessible Science Articles
National Geographic (2021). What will happen when the Sun dies?
https://www.nationalgeographic.com/science/article/sun-death-white-dwarf-future-earth
BBC Science Focus (2023). How long does the Earth have left to support life?
https://www.sciencefocus.com/planet-earth/how-long-will-earth-remain-habitable
Space.com (2024). Earth’s fate: When the Sun becomes a red giant.
https://www.space.com/sun-red-giant-earth-future
Scientific American (2019). The Long Goodbye: Earth’s Final Days.
https://www.scientificamerican.com/article/the-long-goodbye-earths-final-days
6. Philosophical and Existential Reflections
Rees, M. (2003). Our Final Hour: A Scientist’s Warning. Basic Books.
- A deeply philosophical exploration of human-made existential risks.
Dyson, F. J. (1979). Time without end: Physics and biology in an open universe. Reviews of Modern Physics, 51(3), 447–460.
- A visionary physicist’s meditation on the very long-term fate of life and consciousness.
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