(Beeps)

[Countdown]

(Clapboard claps)

Ten years is a long time for us humans on earth.

Ten turns around the sun.

When I was on the TED stage a decade ago,

I talked about planetary boundaries

that keep our planet in a state that allowed humanity to prosper.

The main point is that once you transgress one,

the risks start multiplying.

The planetary boundaries are all deeply connected,

but climate, alongside biodiversity, are core boundaries.

They impact on all others.

Back then we really thought we had more time.

The warning lights were on, absolutely,

but no unstoppable change had been triggered.

Since my talk, we have increasing evidence

that we are rapidly moving away

from the safe operating space for humanity on earth.

Climate has reached a global crisis point.

We have now had 10 years of record-breaking climate extremes:

fires blaze in Australia, Siberia, California and the Amazon,

floods in China, Bangladesh and India.

We're now enduring heat waves across the entire northern hemisphere.

We risk crossing tipping points

that shift the planet from being our best resilient friend,

dampening our impacts,

to start working against us, amplifying the heat.

For the first time, we are forced to consider the real risk

of destabilizing the entire planet.

Our children can see this.

They are walking out of school to demand action,

looking with disbelief at our inability to deviate away

from potentially catastrophic risks.

The next 10 years, to 2030,

must see the most profound transformation the world has ever known.

This is our mission.

This is the countdown.

(Clock ticks)

When my scientific colleagues summarized, about a decade ago,

for the first time,

the state of knowledge on climate tipping points,

just one place had strong evidence that it was on a serious downward spiral.

Arctic sea ice. (Water sounds)

Other tipping points were long way off --

50 or 100 turns around the sun.

Just last year we revisited these systems,

and I got the shock of my career.

We are only a few decades away from an Arctic without sea ice in summer.

In Siberia, permafrost is now thawing at dramatic scales.

Greenland is losing trillions of tons of ice

and may be approaching a tipping point.

The great forests of the North

are burning with plumes of smoke the size of Europe.

The Atlantic ocean circulation is slowing.

The Amazon rainforest is weakening

and may start emitting carbon within 15 years.

Half of the coral of the Great Barrier Reef has died.

West Antarctica may have crossed the tipping point already today.

And now, the most solid of glaciers on earth, East Antarctica,

parts of it are becoming unstable.

Nine out of the 15 big biophysical systems that regulate climate are now on the move,

showing worrying signs of decline

and potentially approaching tipping points.

Tipping points bring three threats.

First, sea level rise.

We can already expect up to one meter this century.

This will endanger the homes of 200 million people.

But when we add the melting ice from Antarctica and Greenland

into the equation,

this might lead to a two meter rise.

But it won't stop there, it will keep on getting worse.

Second, if our carbon stores like permafrost and forest

flip to belching carbon,

then this makes the job of stabilizing temperatures so much harder.

And third, these systems are all linked like dominoes:

If you cross one tipping point, you lurch closer to others.

Let's stop for a moment and look at where we are.

The foundation of our civilization is a stable climate

and a rich diversity of life.

Everything, I mean everything, is based on this.

Civilization has thrived in a Goldilocks zone:

not too hot, not too cold.

This is what we have had for 10,000 years since we left the last ice age.

Let's zoom out a little here.

Three million years --

temperatures have never broken through the two degrees Celsius limit.

Earth has self-regulated within a very narrow range

of plus two degrees in a warm interglacial,

minus four degrees, deep ice age.

Now, we are following a path

that would take us to a three to four degree world

in just three generations.

We would be rewinding the climate clock, not one million, not two million,

but five to 10 million years.

We are drifting towards hot-house earth.

For each one degree rise,

one billion people will be forced to live in conditions

that we today largely consider uninhabitable.

This is not a climate emergency, it is a planetary emergency.

My fear is not that Earth will fall over a cliff

on the 1st of January, 2030.

My fear is that we press unstoppable buttons in the Earth system.

What happens in the next 10 years

will likely determine the state of the planet we hand over

for future generations.

Our children have every reason to be alarmed.

We need to get serious about stabilizing our planet.

Two frontiers will guide this transformation.

The first one is in science.

Here's a new equation for a sustainable planet:

planetary boundaries plus global commons

equals planetary stewardship.

We need to a safe corridor for humanity

to allow us all to become stewards of the entire planet,

not to save the planet but to provide a good future for all people.

And the second frontier is in society.

We need a new economic logic based on well-being.

We are now in a position to provide science-based targets

for all global commons for all companies and cities in the world.

First task, we need to cut global emissions by half by 2030

and reach net-zero by 2050 or sooner.

This means decarbonizing the big systems that run our lives:

energy, industry, transport, buildings.

The fossil fuel era is over.

We need to transform agriculture from a source of emissions

to a store of carbon,

and critically, we must protect our oceans and land,

the natural ecosystems that absorb half of our emissions.

The good news is, we can do this.

We have the knowledge. We have the technology.

We know it makes social and economic sense.

And when we succeed, we can all take lungfuls of fresh air.

We will be saying hello to healthy lifestyles

and resilient economies in livable cities.

We are all on this journey around the sun together.

This is our only home.

This is our mission: to protect our children's future.

Thank you.

(Lights click off)