Chapter 5
The Modern Revolution and the Future

Today, humans are the dominant species on Earth—eight billion of us, wired together in one restless, global network. Our actions shape the fate of the entire biosphere. Some geologists even argue we've entered a new epoch: the Anthropocene, the Age of Us.

From Beanie Babies to the International Space Station, 300,000 years of collective learning has yielded mixed results. Standards of living rose, populations expanded, and—for better or worse—humanity now wields enormous power to reshape the planet and the future of every species living on it. Most important, the Modern Revolution has caused the pace of change to accelerate, throwing history into hyperdrive.

There was a time when human hands supplied all the energy our species needed. We walked everywhere, foraged for food, shaped stone tools with our hands, and burned fallen trees for heat. Things sped up with the domestication of plants and animals, but for almost all of the last 12,000 years, we got all our energy from the Sun, from the wind and water, and from the work of humans and animals. But muscle power could only take us so far.

Then, about 300 years ago, the island nation of England ran out of wood. This changed everything.

Coal is a type of fossil fuel. Fossil fuels are energy-rich substances formed when the remains of prehistoric plants and animals buried underground for millions of years undergo immense geologic pressure. Demand for coal was so high that it sparked a wave of innovation. The most important invention was the steam engine. Originally used to pump water out of England's soggy coal mines, the steam engine soon powered cotton mills, locomotives, and ships. By the 1800s, engines were everywhere, and the Industrial Revolution was in full swing.

Coal and steam turned out to be humanity's first taste of unlimited power, and we overindulged. By the late nineteenth century, cities lit the night sky, railroads laced the continents, and factories filled our skies with pollution. The world got smaller and far more complicated.

Dig Deeper: How is coal mined?

The Industrial Revolution was powered by coal, but it rewired almost everything about the societies it touched. Cities swelled as people left farms for factory jobs, drawn by wages and trapped by smog. Steam engines multiplied output, moving goods and people faster than ever. Production soared. So did pollution. Each new machine demanded more coal, more iron, more labor, more everything. Industrialization sparked new inventions, new wealth, and new inequalities. Humanity entered a fossil-fueled growth spurt.

Humanity's fossil-fuel addiction is changing the planet at record speed. Burning fossil fuels releases greenhouse gases like carbon dioxide (CO₂). These gases trap heat in our atmosphere, which warms the planet. As CO₂ levels climb, ecosystems everywhere are collapsing. Many biologists argue that we're already deep into Earth's sixth great extinction, and this one has our fingerprints all over it.

Geologists divide Earth's deep history into eons, eras, periods, and epochs—units of time that mark the planet's biggest turning points. The Dutch chemist and Nobel laureate Paul Crutzen proposed that we've recently entered a new epoch: the Anthropocene, meaning “the Age of Humans.” His argument was simple. Human activity has changed Earth's systems so profoundly that our impact will be visible in the geological record for millions of years.

Big History is an unfinished story. We've crossed eight thresholds of increasing complexity. Each threshold sparked when the right ingredients met their Goldilocks Conditions. So, what comes next? What new combinations could push complexity even further? And what part will you play in shaping it?

History—even 13.8 billion years of it—doesn't give us a crystal ball, but it does offer some patterns we can use to think about the future. So, what does the history of the Universe tell you about yourself? What does it suggest about the future?

We can't predict the future, but we can spot some big trends. Climate change, AI, and biotechnology are reshaping the biosphere at record speed. Advances in space exploration hint that humans might soon spread beyond Earth the way our ancestors once spread across continents. Welcome to the future. We're entering uncharted waters here, and it's your job to make the map.

Climate history and future

Earth's climate has never stood still—but humans are now changing it faster than nature ever did. This video explores how past climate shifts shaped life on Earth, and what they can teach us about surviving the one we're causing now. The challenge isn't just saving the planet—it's learning to live responsibly on a dynamic one.

Strangely, the far future is easier to imagine than the next century. The physics is simple: In roughly 5 billion years, the Sun will swell and consume the inner planets of our Solar System, Earth included. The Universe itself is expanding faster and faster. Eventually, galaxies will drift apart, stars will burn out, and black holes will swallow the leftovers. The cosmos will end not with a bang, but a long, cold fade into simplicity. Luckily, we have some time before that happens—perhaps trillions of years. For now, we are living in the Universe's youth, while energy and creativity still abound.

Deep space travel

For most of history, the stars were out of reach. Now, they're the next frontier. From satellites to interplanetary probes, humanity is testing how far collective learning can travel. This video looks at space as the possible ninth threshold, as we seek to move life beyond Earth's cradle.

Our near future is murkier and far more urgent. The same ingenuity that built the modern world now threatens to destabilize it. We face warming oceans, dwindling biodiversity, and a planet straining under the weight of eight billion people. Yet collective learning is still our best tool. We can get better at collaborating, sharing data, and facing global problems together.

The next threshold may not spring from a lab or launchpad. It might emerge from how well we learn to manage ourselves. Whether it's restoring Earth's balance, redesigning our societies, or improving global governance, the outcome depends on the decisions being made right now. At present, we can see both dangerous trends, such as global warming and the continued existence and insistence on nuclear weapons, as well as positive trends, such as increased collaboration in dealing with climate change, a slowing in population growth, and an acceleration in our knowledge about the biosphere.

History suggests that complexity doesn't stop. The question isn't if there will be a next threshold. It's whether we'll be ready for it and what kind of world we'll build when it arrives.

Life on Mars (Podcast)

Mars has always been the stuff of myth. Now, it's becoming an engineering problem. In this podcast, David Christian and astrobiologist David Flannery imagine what life might look like on the Red Planet—thin air, long days, and plenty of dust.