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The Human Planet: How We Created the Anthropocene

By Simon Lewis and Mark A. Maslin

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Since the dawn of the Industrial Revolution we have released 2.2 trillion metric tonnes of carbon dioxide into the atmosphere, increasing levels by 44 per cent. This is acidifying the world’s oceans and raising the Earth’s temperature.

The unusually stable environmental conditions that began about 10,000 years ago, when farming emerged and increasingly complex civilizations developed, are over.

Can humans flourish on a rapidly changing planet, or is the future one of grim survival, or even our own extinction?

Perhaps we have prodded Earth one too many times and awoken a monster.

Today human actions constitute a new force of nature, increasingly determining the future of the only planet known to harbour life.

A dangerous experiment with the future of human civilization has begun.

The Anthropocene began with widespread colonialism and slavery: it is a story of how people treat the environment and how people treat each other.

The Anthropocene is one of the most arresting ideas to emerge from science in recent years. It could radically change the world.

The future of the only place in the universe where life is known to exist is increasingly being determined by human actions.

One key scientific challenge of our time is to understand the power we have. Only then will we be able to answer the political question of our age more wisely: what should we do with this immense power?

The idea that the Anthropocene is an ‘accidental’ occurrence – people just did not know what they were doing – is, again, the least discomforting to the status quo, allowing those in positions of power to avoid responsibility for today’s environmental problems.

Over the past 250 years, geologists have carefully pieced together a history of the Earth, one of the major collective intellectual feats of humanity.

Nonetheless, whether society stops emitting large quantities of carbon dioxide or we finally run out of fossil fuels, the climate impacts will not last a geologically important length of time in the context of Earth’s history.

Early farmers caused atmospheric carbon dioxide to rise from 260 ppm (parts per million) some 7,000 years ago to 280 ppm by the beginning of the Industrial Revolution, a rise of 0.003 ppm per year.

During the Industrial Revolution carbon dioxide levels rose from about 280 ppm at its inception to 404 ppm in 2016,

Concentration of carbon dioxide has risen by 1.5 ppm per year since 1958, almost seven times the rate during the early part of the Industrial Revolution.

Since the Industrial Revolution human actions have been changing the global carbon cycle faster than it changed coming out of an ice age, and since the 1950s, at ten or more times that rate.

There is now more carbon dioxide in the atmosphere than has been seen for at least 800,000 years, and possibly several million years.The majority of these additions have been in the past fifty years.

To put these changes in a geological perspective, the difference in mean global temperature between Earth when glaciers were at their maximum extent - when Britain and much of North America were under two miles of ice – and the warm interglacial conditions that human civilization was able to flourish in is approximately 4 to 5°C.

Looking into the past, carbon dioxide levels were similar to today at about 400 ppm around 3 million years ago, but at this time sea levels were 10–30 metres higher.

Scientists recently suggested a new way to understand both the scale and multifaceted nature of human disruption of the global environment:

The boundary for climate is 350 ppm of carbon dioxide in the atmosphere, which is well below the 2016 level of 404 ppm. This indicates that we are running a very dangerous experiment as we use more fossil fuels.

Will the remarkable changes humans have wrought last? One approach is to ask: What would happen if humans suddenly disappeared?

We do not know of any way of removing humans that would not cause huge disturbances to the Earth system. Either a global pandemic or nuclear war would leave billions of human bodies rotting and contaminating the environment.

From studying past climate events we can estimate how long it would take for the global carbon cycle to recover

One such event is the Palaeocene–Eocene Thermal Maximum climatic event 56 million years ago.

A huge release of methane drove a 5°C rise in global temperatures over just a few thousand years, with obvious parallels to today’s fast global warming.

The result was hotter and more humid conditions. Earth was essentially ice-free.

Current evidence suggests that the added carbon took between 150,000 and 200,000 years to be removed from the atmosphere

If human impacts on the carbon cycle stopped today, our legacy would probably run to almost 200,000 years into the future.

We are a force of nature: the chemical composition of the atmosphere, the acidity of the oceans and the energy balance of Earth is in our hands.

At the beginning of the book we asked two questions that require a positive answer in order to be able to say that we are living in the Anthropocene.

First, is Earth in a new state or is it irreversibly headed towards a new state, caused by humans, and on a similar scale to past geological shifts caused by plate tectonics, massive volcanic eruptions and meteorite strikes? And then, is there measurable physical evidence of this new state captured in geological archives, those natural data storages devices that document critical shifts over its history?

The re-threading of Earth’s surface into a single global ecology shows that humans are changing the Earth system from one distinct state towards another.

These changes will play out over millions of years, a geologically meaningful amount of time.

Our cities, rubbish-dumps, plastic pollution in the oceans and much more will become a thin but clear marker within future rocks.

It is safe to conclude that we live in the Anthropocene.

We ought to try to face reality – as we can best understand it – in order to address the monumental challenges of living in a dangerous new epoch.

It is the emergence of a single global interconnected network of cultures powered by a vast use of energy and coordinated by the management of huge amounts of information that has led to humans becoming a force of nature.

The critical question is: will this mega-civilization continue?

If the world’s population consumes resources at the same rate as those in the UK, US, France, Australia or Japan, we face environmental catastrophe.

But it is a tall order for greenhouse gas emissions to reach net zero emission globally across energy, infrastructure, industry, transport and land use within the next few decades. So how do we get there?

Restructuring the global energy system is an unparalleled opportunity to re-engineer it to deliver benefits much more equally, avoid energy poverty and increase freedom.

People’s increased ability to access information without mediation by the old gate-keepers of chiefs, priests, monarchs, governments and newspaper proprietors represents an epochal shift.

This allows people to organize and coordinate activities which are not necessarily controlled by governments, the media or powerful interest groups.

In the UK enough energy is produced so that nobody need be in fuel poverty, but many are. There are empty houses, but people are homeless. The limitation to living freely and without want is political: it is about who owns and controls resources.

At the core of today’s mode of living is the drive for ever-greater labour productivity, organized on the basis of class.

The end of this book is not the place to sketch a political programme for humanity to manage itself in the human epoch, including a possible shift from our current mode of living.

We finish with two important ideas that we think should be further investigated,

What is clear is that the future of the only place in the universe where life is known to exist is being increasingly determined by human actions.

Arriving at necessary common global agreements to manage Earth collectively, will be difficult, but we cannot afford to fail.