Olivera Tecuna is taking us to his village. I don't.

Think we're going to get much further.

It's a five-hour journey. I don't think we're going to have to get out. At least normally.

That's supposed to be the hardest bit, but we'll see.

The Amazon Rainforest has been through its worst drought on record. Its rivers, lakes, and streams drying up. So we.

Should be able to pass through here normally, even at the end of the dry season, but we're.

Getting stuck. It's a little dry, it's a little dry, but I've never seen it. It's dry.

And it's hot. Brazil is in the midst of a heat wave. Olivera's community, 40 families in the middle of the Amazon, has been badly affected by the drought. They're struggling to access clean water to bathe. Crops are affected too. And getting to and from the city is difficult. I think.

That's the end of the line. We've been traveling for nearly five hours now, and Olivia says we're not even halfway, so it looks like we're going to have to turn back. Are you worried about how the weather and the climate here is changing?

Thousands of thousands of thousands of thousands of thousands. Thousands of thousands of thousands.

Of thousands. Thousands of villages have been cut off by this drought. Over 100,000 people. But scientists are worried that this is an indication of something even more catastrophic, an ecological disaster. And there are signs. In two major lakes, dolphins have been turning up dead.

And what happened this year is something that we've never seen before. Nobody's been seeing before. It's unprecedented. We are used to seeing dolphins from the king in the lake every day, and we go by them, and we see babies and everything. And all of a sudden, one day we woke up and there were 20 carcasses along the shores. And then five days later, we had 70 carcasses. It was just devastating.

It was such a shock that the Brazilian government sent an emergency team to try to figure out what was happening. In some places, the water was up to 40.9 degrees Celsius, three degrees higher than human and dolphin body temperature.

What you do, that's where you live, and all of a sudden, you're in the middle of the soup, and you can't get away.

You've lived in the Amazon for a long time? For 30 years. Have you ever seen anything like this drought?

Never, never, never, never even thought about it.

The fear is that the forest is racing towards a theoretical tipping point. In the vast Amazon, water evaporates from the trees to form rain clouds, and in this way, it feeds itself the water it needs to sustain life. If vast swathes of the forest die, it may not be able to do that. And the Amazon would keep dying and faster in a catastrophic feedback loop.

This is the heart of the Amazon, and this is what the air is like. Just thick with smoke.

You can smell it. More signs that the forest is losing the ability to recover. When it's dry, small fires set to clear land for planting burn out of control. The Amazon saw more fires in the past year in its primary or untouched forest. We have lots of fires.

If you can see in the morning, you can hardly see anything here because it's so smuggy, and you can actually feel it. We've been coughing a lot. Scientists have been saying for years that this was going to happen to the Amazon in 2030, 2050, just getting worse and worse, and that we were going to be like Savannah, which is the dry areas. But I never expected to see it this dramatically. It was just too quick. It happened just.

Like that. You didn't think it would happen in your lifetime? No.

We live in the water. We depend on the water to drink, to bathe, to travel for everything. And the water is much less.

About 17 % of the Amazon has been deforeested since the 1970s. And if that figure hits 25 % and global temperature rises more than 2.5 degrees Celsius, then scientists say the tipping point could be triggered. It would be a disaster for millions of people south of the Amazon who rely on it to produce rainfall, and for the billions of us who rely on the rainforest to help keep the planet cool. The Amazon stores around 150 billion metric tons of carbon.

Do we have rain?

Yes, finally, but perhaps not for long.

Yeah, not enough.

Well, the climatologists are saying this route will continue.

Flavia Costa researches the health of plants and trees in the forest.

We got to see some plants that are already showing signs of being dead. Some colleagues that are flying drones, they say they can see also canopies that are completely defoliated.

It's too soon to assess what this drought has done to the Amazon, but the last big one in 2015 can give us a clue.

We have seen very large mortality in the last drought. When on average, the Amazon stopped to function as a carbon sink, and we mostly expect the same now, as I said. Yeah, there might be a moment where the forest starts to lose the capacity to recover. But this is probably not widespread. So some regions will probably become savanas, but there are pockets of forest that probably will remain.

With the rains here now, the forest can recover. But next year, another drought is predicted, and the question is, can it recover enough?

We always say these animals are sentinels and because they feel first what's going to come to us. That's why I say it's a slap on the face because it's happening to them. It's going to happen to us.

Are you scared?

Well, I am because not only because of the forest. I live here. I understand the drama of the population. Imagine if every five years we have a drought and each drought is a bit worse than the before, then the forest may really not stand and we might see this tipping point faster than what we were expecting.

We are guilty of this. We are guilty of this. We are guilty of this. We are guilty of this. We are not tentative to this. We are not trying to defend our mother, and today, we are screaming for help for their children. We are them. We know that it's a little late. We are not...