Humanity has its hands full right now with global climate change, which promises centuries of stronger storms, longer droughts and other magnified disasters. Earth has seen a lot of climatic chaos in its 4.5 billion years, although usually at a much slower pace. Our species is just too young to know what it's like, having evolved only about 200,000 years ago during a relatively tranquil window in time.
Now, by overstuffing the sky with carbon dioxide, we're beginning to realize how lucky we've been. The human-aided greenhouse effect is already wreaking havoc with climates and ecosystems around the planet, threatening to undermine all our success over the last few millennia. Yet despite the world-changing urgency of climate change, nature is also capable of even greater devastation. Just ask the dinosaurs.
The universe sends us occasional reminders about this, from asteroid flybys to meteors that explode in our atmosphere like 440,000 tons of TNT. Earth periodically reveals its own volatility, too, surprising us with earthquakes and volcanic eruptions. And even space might not be exempt from the long slog toward apocalypse: The recently discovered Higgs boson, for example, may spell doom for the universe.
The distant future will also bring plenty of good news and innocuous oddities, but those don't usually captivate us eons in advance like catastrophes do. It's all worth considering, though, if it can remind us to appreciate what we have now and to work harder at sustaining it. Homo sapiens may be a long shot to survive the next 100 trillion years — especially since we've only made it 0.0000002 percent of the way so far — but the fact we're thinking about it now at least gives us a fighting chance.
On that note, here's an Earth-centric peek into the faraway future. It's all speculative, of course, and anyone alive today won't be around to fact-check most of it. Still, it's based on the work of astronomers, geologists and other scientists, unlike many doomsday predictions. All events are listed by number of years from present day:
100 years: A sweltering century
Earth continues to heat up, possibly by as much as 10.8 degrees Fahrenheit (a change of 6 degrees Celsius) from today's average temperature. This spurs a cascade of crises around the world, including more severe droughts, wildfires, floods and food shortages caused by changing weather patterns. Sea levels are 1 to 4 feet (0.3 to 1.2 meters) higher than today, and the Atlantic generates more "very intense" hurricanes. The Arctic is ice-free in summer, amplifying climate change even further.
200 years: Live long and prosper?
Human life expectancy is rising, helping more and more people live beyond 100. Yet while population growth has slowed, there are still roughly 9 billion of us straining Earth's resources. Climate change has killed countless people, wiped out valuable wildlife and caused key ecosystems to collapse. Our great-grandchildren try to forgive us for this mess, even though CO2 emissions from our era are still trapping heat in the atmosphere. On the bright side, however, technology has also offset some climate-related problems, improving crop yields, health care and energy efficiency.
300 years: Humanity makes the big leagues
Created by Soviet astronomer Nikolai Kardashev, the Kardashev scale ranks advanced civilizations based on their energy sources. A Type I civilization uses all available resources on its home planet, while Type II taps the full energy of a star and Type III harnesses galactic power. American physicist Michio Kaku has predicted humanity will be a Type I civilization by the 2300s.
860 years: Duck!
The asteroid 1950 DA will pass scarily close to Earth on March 16, 2880. Although a collision is possible, NASA predicts it will narrowly miss, providing an important reminder of what's to come — and another reason to celebrate on St. Patrick's Day.
1,000 years: Duck even more!
2,000 years: Pole position
The planet's north and south magnetic poles periodically reverse, with the last switch occurring in the Stone Age. It may already be under way again today, but since it's a slow process, the North Pole probably won't be in Antarctica for a few millennia.
8,000 years: Dancing with the stars
As if pole reversal wasn't confusing enough, gradual changes in Earth's rotation have now dethroned Polaris as the North Star, replacing it with Deneb. But Deneb will later be usurped by Vega, which will give way to Thuban, eventually setting the stage for Polaris to regain the role in 26,000 years.
50,000 years: Cooling-off period
Unless excess greenhouse gases are still scrambling Earth's climate, the current interglacial period finally ends, triggering a new glacial period of the ongoing ice age.
100,000 years: Canis Majoris goes wild
The largest known star in the Milky Way has finally exploded, producing one of the most spectacular supernovas in galactic history. It's visible from Earth in daylight.
100,000 years: A supervolcano erupts
There are about 20 known supervolcanoes on Earth, including a famous one under Yellowstone, and together they average a major eruption once every 100,000 years or so. At least one has probably erupted by now, releasing up to 100 cubic miles (417 cubic kilometers) of magma and causing widespread death and destruction.
200,000 years: A new night sky
Due to "proper motion," or the long-term movement of celestial bodies through space, familiar constellations (like Orion or Perseus) and asterisms (like the Big Dipper) no longer exist as we see them from Earth today.
250,000 years: Hawaii has a baby
Loihi, a young submarine volcano in the Hawaiian chain, rises above the Pacific Ocean's surface and becomes a new island. (Some estimates project this will happen earlier, maybe within 10,000 or 100,000 years, but it also might never happen.)
1 million years: A supervolcano erupts even more
If you thought 100 cubic miles of magma was bad, wait a few thousand centuries and you'll probably see a supervolcano spew up to seven times that amount.
1.4 million years: Constant comet
Orange dwarf star Gliese 710 passes within 1.1 light-years of our sun, causing a gravitational disruption in the Oort Cloud. This dislodges objects from the solar system's icy halo, possibly sending a salvo of comets toward the sun — and us.
10 million years: Sea plus
30 million years: Where's Bruce Willis?
An asteroid 6 to 12 miles (10 to 19 km) wide hits Earth about once per 100 million years on average, and the last one hit 65 million years ago. That suggests another one may strike in the next 30 million years or so, releasing as much energy as 100 million megatons of TNT. It would blanket the planet in debris, spark vast wildfires and trigger a severe greenhouse effect. Dust would also darken the sky for years, possibly offsetting some of the greenhouse effect but also hindering plant growth.
50 million years: Sea minus
Africa collides with Eurasia, closing up the Mediterranean Sea and replacing it with a Himalayan-scale mountain range. At the same time, Australia is migrating north and the Atlantic Ocean continues to widen.
250 million years: Continents, unite!
Continental drift once again smashes Earth's dry land into a supercontinent, which resembles the ancient Pangea. Scientists are already calling it Pangea Proxima.
600 million years: Earth needs some shade
The sun's growing luminosity increases the weathering of surface rocks on Earth, trapping carbon dioxide in the ground. Rocks dry up and harden due to faster evaporation of water. Plate tectonics slow down, volcanoes stop recycling carbon into the air and carbon dioxide levels begin to fall. This eventually impedes C3 photosynthesis, likely killing off most of the planet's plant life.
800 million years: Multicellular life dies out
The ongoing decline of carbon dioxide levels makes C4 photosynthesis impossible. Unless humans have devised some kind of geoengineering scheme to preserve the food web — and without accidentally triggering some new kind of calamity in the process — Earth's biosphere is reduced to single-celled organisms.
1 billion years: Earth can't hold water
The sun is now 10 percent more luminous, heating up Earth's surface to an average 116 degrees Fahrenheit (47 Celsius). The oceans begin to evaporate, flooding the atmosphere with water vapor and spurring an extreme greenhouse effect.
1.3 billion years: Mars is on the bubble
CO2 depletion kills off Earth's eukaryotes, leaving only prokaryotic life. But on the bright side (literally, and maybe figuratively), the sun's growing luminosity is also expanding the solar system's habitable zone toward Mars, where surface temperatures may soon resemble those of ice-age Earth.
2 billion years: Solar system could go spinning into space
A galactic collision of catastrophic proportions between the Large Magellanic Cloud, the brightest satellite galaxy of the Milky Way, and the Milky Way could wake up our galaxy's dormant black hole, according to astrophysicists from Durham University in the U.K. If the black hole is startled, it would consume surrounding gases and increase 10 times in size. Then, the hole would spew out high-energy radiation. While the researchers don't believe it will affect Earth, it does have the potential to send our solar system careening through space.
2.8 billion years: Earth is dead
Earth's average surface temperature rises to nearly 300 degrees Fahrenheit (about 150 Celsius), even at the poles. The scattered remnants of single-celled life will likely die out, leaving Earth lifeless for the first time in billions of years. If humans still exist, we'd better be somewhere else by now.
4 billion years: Welcome to 'Milkomeda'
There's a good chance the Andromeda galaxy has collided with the Milky Way by now, starting a merger that will produce a new galaxy called "Milkomeda."
5 billion years: The sun is a red giant
Having used up its hydrogen supply, the sun grows into a red giant with a radius 200 times larger than today. The solar system's innermost planets are destroyed.
8 billion years: Titan seems nice
The sun has completed its red giant stage and may have destroyed the Earth. It's a white dwarf now, shrinking to nearly half its current mass. Meanwhile, rising surface temperatures on Saturn's moon Titan might be able to support life as we know it. That could be an enticing change from current conditions on Titan, which have inspired speculation about alien life but wouldn't be very hospitable for Earthlings.
15 billion years: Black dwarf sun
With its main-sequence life at an end, the sun cools and dims into a hypothetical black dwarf. (This is hypothetical because the estimated length of the process is longer than the universe's current age, so black dwarfs probably don't exist today.)
1 trillion years: Peak stardust
As supplies of star-producing gas clouds run low, many galaxies begin to burn out.
The universe's star-forming 'Stelliferous Era' is expected to end in 100 trillion years, leaving behind a dark, ghostly cosmos populated by black holes. (Image: M. Alvarez, T. Abel and J. Wise/KIPAC/SLAC/NASA)
100 trillion years: The end of a Stellar Era
Star formation has ended and the last main-sequence stars are dying, leaving only dwarf stars, neutron stars and black holes. The latter gradually eat any leftover rogue planets. The universe is near the end of its current Stelliferous Era (aka "Stellar Era"), when most energy came from thermonuclear fusion in the cores of stars.
10 undecillion (1036) years: What a bunch of degenerates
The Stelliferous Era finally gives way to the Degenerate Era, as the only remaining energy sources in the universe are proton decay and particle annihilation.
10 tredecillion (1042) years: Back in black
The Black Hole Era begins, populated by little more than black holes and subatomic particles. Due to the universe's ongoing expansion, even those are hard to find.
Googol (10100) years: A shot in the dark
After many eons of black hole evaporation, the universe as we know it lies in ruins, reduced to a sparse junkyard of photons, neutrinos, electrons and positrons. An array of theories speculate about what happens next, including the Big Freeze, the Big Rip, the Big Crunch and the Big Bounce — not to mention the idea of a multiverse — but it's widely believed our universe will expand forever.
1010^10^76.66 years: Second (uni)verse, same as the first?
The universe may be in ruins, but given enough time, some futurists think something incredible will happen. It's like an endless string of poker games: Eventually you'll be dealt the exact same hand many times. According to 19th-century mathematician Henri Poincaré, quantum fluctuations in a system with fixed total energy will also re-create similar versions of history over inconceivable time scales. In 1994, physicist Don N. Page estimated the duration of "Poincaré recurrence time," describing it as "the longest finite times that have so far been explicitly calculated by any physicist."
Even if dying black holes leave nothing behind, however — and if quantum quirks don't grant us a cosmic mulligan — many physicists and philosophers still think nothing might actually be something. As astrophysicist Neil deGrasse Tyson said in 2013 during a debate on the nature of nothingness, "If laws of physics still apply, the laws of physics are not nothing."
In other words, we have nothing to worry about.
Editor's note: This article has been updated since it was originally published in May 2013.