The human era

"Humans have reshaped the planet, but at a steep cost."

Epoch: a subdivision of a geologic period

Humans are the most powerful species ever to live on Earth, and we got that way really fast—maybe too fast. We’ve spent most of our recent history making major discoveries and innovations, all while using energy sources we found deep in the ground. This energy has helped us generate electricity, power our factories, and fuel our vehicles—all the incredible things we’ve used to build our world and launch the modern revolution. But our use of this energy has also caused major problems. Most importantly, human activity is today driving big changes to Earth’s climate.

Climate change has been a part of life on this planet as long as there has been life on this planet. Longer, actually. In the past, natural climate change created major cooling and warming events that repeatedly reshaped Earth and all the life on it. Over billions of years, Earth has witnessed major climate events, species extinctions, and catastrophes. One of those climate events likely led to the appearance of modern humans, who evolved in response to a warming world. Another warming event about 12,000 years ago probably sparked the Agricultural Revolution.

Yes, climate change has always been part of life on Earth. But in the last 300 years, human activity has produced a new type of climate change, and it’s happening very fast. During the Modern Revolution, humans have transformed the planet, but at a steep cost. Some scientists argue that people are changing the Earth so much, so fast, that our impacts will be visible in the geological layers of the Earth millions of years from now. They claim that we have launched a new epoch: the Anthropocene.

The Anthropocene

Now, the Anthropocene isn't an official epoch—yet. But scientists who use the term say that human activity has profoundly changed the planet on every level, pointing to climate change as the biggest example.

Human impacts on the Earth’s climate started off slow. Most of human history has happened during an epoch called the Holocene. The Holocene was a warm period in Earth’s history, it followed the last big ice age, and for 12,000 years, the climate has been relatively stable and mild. Humans took advantage of this climate and developed agricultural systems and complex societies. Humans cut down forests, built cities, and did lots of big stuff. But in general, our impacts on Earth’s climate remained limited.

Then, about 300 years ago, we reached the most recent threshold of increasing complexity. The Modern Revolution started when people began using fossil fuels to power machines. These nonrenewable energy sources include coal, oil, and gas, and they’ve changed our entire world. Fossil fuels allowed humans to industrialize—mass-producing goods in factories and traveling long distances in trains, steamships, cars, and airplanes. Today, fossil fuels continue to power our homes, cars, electronics, manufacturing, farming, and so much more. At this point, they’re an essential part of how over 8 billion humans eat, move, work, and play.

What’s causing climate change?

Fossil fuels have a big downside. When we burn them, they release greenhouse gases. These gases—like carbon dioxide—collect in Earth’s atmosphere and trap heat from the sun, causing Earth to warm, much like it has over billions of years during similar climate shifts. Except this time the process is happening faster, and it’s driven by human actions.

The greenhouse gases in our atmosphere trap more heat from the sun on the surface of the planet, intensifying a natural process called the greenhouse effect. This intensified greenhouse effect is destabilizing our environment and threatening our planet.

This warming has created serious problems, including major shifts in temperature; rising sea levels; and more-dangerous, more-extreme, and more-frequent weather events such as wildfires, floods, hurricanes, and tornadoes.

Climate changes have happened before in Earth’s history, but those changes took tens of thousands of years. Today, changes are taking place before our eyes, reshaping the planet within a single generation, a single lifetime.

Addressing climate change

Individuals, companies, and governments are working hard to address climate change, but solutions require rethinking many aspects of our societies and the technology we use.

Humans today are burning a lot of fossil fuels and we’re burning them really fast. Each year, we release about 51 billion tons of greenhouse gases into the atmosphere. If that number sounds big, it’s because it is. Pretty much everything we do runs on fossil fuels, from turning on lights in our homes and powering up our computers to building houses and eating hamburgers. But bringing down that 51-billion-ton number is really important for decarbonization. Unless we slow down our greenhouse gas emissions, climate change will continue to speed up, and the changes we see will get worse.

Decarbonizing is really hard, but it’s not impossible. Human dependence on nonrenewable sources of energy like fossil fuels is causing modern climate change. And while it can be difficult to replace fossil fuels, there are renewable energy sources like solar, wind, and water, which can all be used to produce electricity without releasing greenhouse gases.

Solving these problems will take a lot of work, and we don’t have much time. Scientists largely agree that the next few years will be a critical time for action. If we don’t make major changes—and quickly—our world will become a challenging place for humans to live.

But there are ways we can avoid that, and not just through using the wind and Sun to power our cars and computers. Researchers are already hard at work trying to harness other energy sources, such as fusion technology, which would replicate the force that powers the Sun—and they’re closer than ever before.

Solutions are possible, and when we find them, our world might be transformed in ways we can’t yet imagine.