At first, it was very simple,

consisting of little more than hydrogen and helium

and lots of energy.

There were no stars or galaxies,

no planets and certainly no living creatures.

Then, gradually, more complex things appeared.

The first stars and galaxies

probably appeared within about 200 million years of the Big Bang.

As big stars lived and died, they blew up and created new elements.

Those new elements allowed the creation of new materials

such as the dust and ice and rocks and minerals

from which planets are made.

Our Sun and solar system appeared about 4.5 billion years ago,

and by 4 billion years ago,

it's likely that life had emerged on Earth.

Life evolved and diversified

but most of it consisted of tiny, single-celled organisms

until, about 1 billion years ago, the first many-celled organisms appeared.

From about five hundred million years ago,

big creatures became much more common,

from trilobites to trees to tyrannosaurus rex.

The first humans evolved very recently,

just about 200,000 years ago.

Though it wasn't obvious at the time,

the appearance of humans turned out to be hugely important

because humans were able to share ideas and information

better than any other species that ever existed.

Using that ability,

our ancestors gradually built up stores of information

that allowed them to control their environments

more and more powerfully.

The process accelerated until, in just the last 100 years,

we have become so powerful that what we do in the next few decades

will determine the future of the oceans,

the climate, and of most other species on Earth,

including our own descendants.

Many scholars believe that this represents a new geological epoch.

The Anthropocene.

In the last 50 years,

we humans have begun to control energy and resources

on such a vast scale that we are transforming the land,

the seas and the atmosphere of the Earth.

So, planet Earth is at a turning point in its history.

Humans, now the dominant species,

will either lead the biosphere towards a flourishing future,

or to catastrophe.

Perhaps triggered by nuclear wars

that could ruin swathes of the planet in just a few hours,

or caused more slowly by the continued release of greenhouse gases

until the land is flooded

and global climates are too hot to grow enough food.

Never before has a single species

determined the future of the entire biosphere.

The good news is that we understand the science,

and we already have many of the technologies needed

to build a sustainable future.

What's missing now is the political technology.

How can governments and peoples

be encouraged to see the challenges that they all share,

rather than simply defending their own local and immediate interests?

Only by collaboration can we avoid the many dangers we face today.

Can we steer planet Earth towards a prosperous future in which humans

and all the other organisms on which we depend can flourish for thousands,

even perhaps, for millions of years into the future?