Eons

We spend a lot of time here on Eons looking backwards into deep time, visiting ancient chapters of our planets history.

But this time, were taking a look towards the deep future.

After all, the story is far from over.

The forces that have shaped the world into what it is today havent stopped and theyll continue shaping the planet for thousands, millions, and billions of years to come.

And as weve improved our understanding of how those forces work by studying the geologic past, weve become the first species in history that can predict global changes ahead of time Allowing us to glimpse future Earths that we humans may not even be around to see Worlds with different ecosystems, different climates, and even different continents from the ones we know today.

And worlds that may or may not come to pass, depending on what we do in this chapter of the planets history.

Heres whats coming up next on Planet Earth.

Planetary-scale changes usually unfold over extremely long time frames - often millions or billions of years spanning geological ages, epochs, and eons.

But if we begin by looking just 10,000 years ahead into the planets future - a blink of an eye in geologic time - what might have changed?

Well, that depends a lot on how the next century or two goes.

If we keep releasing trillions of tons of carbon emissions into the atmosphere this century, the effects may still be impacting the planet 10,000 years from now.

In one major 2016 study, for example, a team of climate scientists calculated four different emissions scenarios and modeled their long term effects thousands of years out.

In the highest emission scenario, the world warms around 7.5 degrees Celsius over the next few centuries and stays that hot 10,000 years in the future.

In this potential future world, we humans essentially recreate the Eocene epoch the span of time between 56 and 34 million years ago, the last time the planet was so warm.

The melting of almost all the land ice from both Antarctica and Greenland raises sea levels around 50 meters over the next several thousand years.

This reshapes global coastlines and swallows up many low-lying areas, like, for example, most of Florida.

And the effects of this rapid warming on the species of future Earth?

We can predict that, too.

See, ecosystems have been affected by abrupt warming before.

Around 56 million years ago, at the beginning of the Eocene, temperatures also rose between 5 and 8 degrees Celsius in under 10,000 years, making it a useful comparison to our modern warming.

This was the start of the Paleocene - Eocene thermal maximum, an event that lasted around 200,000 years.

It was probably triggered by sudden bursts of greenhouse gasses released into the atmosphere from natural sources.

And the fossil record of many species from before and after this rapid warming shows a clear pattern - one thats also a warning for the future Sudden warming shrinks mammals.

The teeth of Sifrhippus, the earliest horse, for example, show that this already pretty small species shrank by around 30% over the first 130,000 years of the event.

At their smallest, they dropped to around just 3.9 kilograms - about the size of a house cat - before rebounding in size and growing by over 75% when the planet cooled back down.

And researchers think that this reversible dwarfing happened at least partly because it increased their surface area to volume ratio.

See, smaller bodies release heat more quickly, which is useful for warm-blooded mammals that have to tightly regulate their body temperatures.

So its possible that, in a much warmer future world, the descendents of today's mammals will shrink too, beating the heat by becoming better at radiating it.

It might also give us another Titanoboa, but thats a different story And while that world 10,000 years from now depends on decisions we make today, some changes in Earths more distant future have been brewing since long before we were around.

Like, 10 million years from now, an entire continent may split itself apart.

This is the possible end result of the modern world's biggest active continental rift: the Eastern African Rift system.

It snakes thousands of miles down the eastern side of the African continent, splitting the Nubian plate from the Somalian plate and slowly pulling them apart.

The rift probably formed somewhere between 30 and 40 million years ago, possibly driven by superheated plumes in the partially-molten mantle layer rising upwards.

These plumes cause the lithosphere above - the planets solid outer shell - to stretch and fracture.

At the current rate, the rift is pulling the continent apart at just 7 millimeters a year or so.

But in about 10 million years, if it doesn't slow down, then even this snails pace may be enough to split the continent in two.

Eventually, a new ocean will form as water floods into the basin that opens between the two sides, creating a huge new eastern African island separated from the rest of the continent.

And, as weve seen many times before, evolution gets pretty weird on islands.

From dodos to dwarf mammoths to gorilla-sized lemurs, islands are evolutionary hotspots, where isolation and unique conditions breed innovation.

So 10 million years from now, newly-isolated species that find themselves on this Madagascar 2.0 may suddenly diverge from their mainland cousins in all sorts of ways.

But there is another possible future.

Instead of splitting the continent in two, the rift system might just fizzle out, as others have before.

Like the Midcontinent Rift of North America, for example, which was on the brink of cracking that continent down the middle a little over a billion years ago.

But its activity stopped shortly before that happened, becoming the biggest known failed rift that still scars the surface of the planet.

Whether the rift in eastern Africa will also fail, or whether it will lead to the first major continental break up in 30 million years, well have to wait 10 million years or so to find out.

When it comes to plate tectonics though, big breakups are only ever temporary And the next stop on our tour of the geological future takes us forward nearly 300 million years, to a world where the continents come back together for the first time since Pangea.

See, one of the longest-term cycles that the planet goes through over time is the supercontinent cycle.

This squishing together of most of the continents happens every 600 million years or so, forming supercontinents that then break up again.

The last one, Pangea, formed around 320 million years ago and it broke up around 170 to 180 million years ago.

And in 2022, researchers modeling the future of this cycle were able to predict how and when the next one might form.

They carried out supercomputer simulations to model the movement of Earths tectonic plates over extremely long timescales.

And the most likely scenario they saw was that, somewhere between 200 and 300 million years into the future, the planet will get a new supercontinent which has already been dubbed Amasia.

The name comes from the pieces that will form it - the collision of Australia, Asia, and the Americas, closing up the Pacific Ocean.

Its a process that is slowly happening as we speak, with the Pacific shrinking by a few centimeters or so a year.

In a future world 300 million years from now, it will potentially cease to exist as the various landmasses it currently separates finally come together again.

And while Amasia is just the latest model, what the formation of any supercontinent will mean for those future ecosystems, well, thats harder to say.

Were closer in time to the earliest dinosaurs than we are to any of those species.

The early dinosaurs got their start on Pangea probably a little over 230 million years ago, with bipedal carnivores like Herrerasaurus.

And they eventually radiated into all kinds of diverse, strange, and awesome species that flourished on land for the rest of the Mesozoic Era.

So while we can model what the continents might look like in the deep future, what the species of that time will look like is something no supercomputer can predict.

But we can say that, whatever lifeforms call that future supercontinent home in 300 million years, many of them will face a major ecological challenge Because the new supercontinents vast interior will become extremely hot and dry, forcing species to once again adapt to radically changing environmental conditions.

Although there are still unknowns surrounding the question of whats next for Earth, looking into the past is a valuable tool that allows us to also glimpse the future.

Because the planet is constantly changing, and while its tempting to think of the present as some sort of end point, Earths story is still unfolding, and there are many chapters still to come.