Are we at risk of destabilizing the whole planet? Recent discoveries made by scientists studying the ways in which our planet works are surely of the greatest importance for all of us. Their insights are deeply troubling. Nonetheless, they also give us hope because they show us how we can fix things.
Johan Rockström has focused on what keeps our planet stable. What he and his colleagues around the world have discovered is perhaps the most important scientific insight of our times. This comes from ice core data, and I think that this is the most important graph we have today. The graph is a revelation.
It shows global temperature variability over the past 100,000 years, since the first appearance of modern humans. We were jumping between plus minus 10 degrees Celsius in a decade. We had, to put it simple, a rough time.
What's critical is that the temperature stabilized just 10,000 years ago. Geologists have given this period of stability its own special name. It's called the Holocene.
The Holocene is remarkable. It is a warm period where the planet's global mean temperature varies between just plus minus one degree Celsius during the entire period. The Holocene's stable temperatures gave us a stable planet.
Sea levels stabilized. For the first time we had predictable seasons and reliable weather. This stability was fundamental. For the first time, civilization was possible and humanity wasted no time in taking advantage. The Holocene is the only state of the planet we know for certain can support the modern world as we know it.
But we have just left the Holocene behind. The exponential rise in human pressures on planet Earth has now reached a stage where we have now created our own geological epoch. We are now in the Anthropocene, the age of humans, because we now are the primary drivers of change on planet Earth. It's just a mind-boggling situation to be in.
For the first time, we have to seriously consider the risk of destabilizing the entire planet. There is a danger that we have already crossed the boundary in Earth's climate. The most alarming evidence of this is in the change of our planet's ice. Having two caps of permanent ice in the Arctic and in Antarctica is the very precondition for the planet to stay in the state that has enabled us to develop civilizations as we know it.
A permanent white surface like what we can see around us here is reflecting back 90-95% of incoming heat from the sun. When these ice sheets start melting, you can come to a point where the ice sheets tip over from being self-cooling to becoming self-warming. And that is the most dramatic tipping point in the Earth's system. A tipping point is a point beyond which a change becomes irreversible.
So in the current climate, Greenland is already beyond its threshold, where it's now losing 10,000 cubic meters of ice per second. That's the average loss rate. Now, that loss rate will only continue as the climate heats up. So is Greenland lost? evidently it is the drama here is that one characteristic of tipping points is that once you press the on button you cannot stop it it takes over it's too late it's not like you could say oops now i realize i didn't want to melt the green and ice sheet.
Let's back off. Then it's too late. The important point to make here is that everything in the Earth's system is connected.
If one part of the climate system crosses its tipping point, then that might make it more likely for other parts of the system to also cross their critical threshold. So you can think of this in terms of dominoes. If you tip one of them over, then this might lead to a cascading effect.
When we cross tipping points, we unleash irreversible changes. That would mean that the planet will go from our best friend's position, where it dampens and reduces the stress, sucking up carbon dioxide, taking up heat, absorbing impacts, and tipping over to a point where it could self-reinforce warming and become a foe. In 1988, we passed 350 parts per million of carbon dioxide in Earth's atmosphere.
This was the moment we crossed the boundary. Ever since then, we've been at risk of triggering changes... that lead to runaway warming. Right now, we've reached a point of carbon dioxide concentration in the atmosphere of roughly 415 parts per million.
We're starting to see the impacts of being in the middle of the danger zone in the climate boundary in terms of rising frequency of droughts and heat waves and floods and accelerated melting of ice and accelerated thawing of permafrost and higher freezing temperatures. frequency of forest fires. Today our assessment is that the uncertainty range in science lies between 350 ppm, which is the boundary between the safe zone and entering the danger zone, up to 450 ppm, which is when you exit the danger zone and go into really high risk zone. If we enter the high risk zone, irreversible tipping points become highly likely, if not inevitable.
And this is a conservative estimate given that the science of tipping points are all around us now. We are fast approaching a major tipping point in one of the planet's largest remaining wildernesses, the Amazon. Large parts of the rainforest are drying out.
As the forest is reduced and fragmented, its ability to recycle water and generate rain into the dry season is diminished. If the dry season becomes longer than four months, the jungle trees die and are replaced by savannah and carbon is released into the atmosphere. Carlos Nobre has calculated the Amazon could release two thousand tons of carbon per year. 200 billion tons over the next 30 years.
That's equivalent to all the carbon emitted worldwide for the past five years. We are very, very close to the tipping point. Are we concerned about fighting the climate crisis? Are we concerned about keeping the carbon in the forests? Or I don't care.
Now that Johan and his colleagues have turned on the headlights, we can clearly see the boundaries. We can see the path back to a safe space, to a more resilient future. It is achievable.
An immediate priority is to reduce carbon emissions to zero and stabilize global temperature as low as we possibly can. Since the beginning of the Industrial Revolution, we have emitted billion tons of carbon dioxide. To stay below 1.5 degrees, we must emit less than 300 billion tons more. If we continue to emit 40 billion tons each year, our budget will run out within seven years.
Of course, we cannot shut down all energy utilities in the world overnight. So the only orderly way to do this is to bend the global curve of emissions now. That's what all science shows. Now is the last chance we have to bend the global curve.
Cutting our emissions in half every decade is an exponential rate of change. Anyone can adopt this pace, and a company can do it, or a country can do it, or the world can slash must do it. The future is not determined.
The future is in our hands. What happens over the next centuries will be determined of how we play our cards this decade. I would say that we do not have environmental problems in the world anymore.
Destabilizing the planet, the risk of destabilizing the planet, is a question of security and stability. for all societies in the world. Therefore, it is a question for the Security Council. It's a remarkable time to be alive, but it also carries great responsibility to act decisively.
We have no time to lose. We still have a chance. The window is still open for us to have a future for humanity.
That, I think, is the beauty of where we are today.