amazon

For over a century, the Nile has been called the longest river on Earth at about 6,650 kilometres. But a stubborn group of scientists argues the Amazon is actually longer — and the disagreement isn't sloppiness. It comes down to a genuinely hard question: where does a river begin, and where does it end? The answer changes the ranking, and reveals why even something as basic as 'how long is this river' has no single correct number.

The Amazon is not Earth's oxygen factory, but it stores vast carbon and recycles rain across a continent. Here is what the evidence says about deforestation, drought, and tipping points.

The Amazon holds tens of billions of tonnes of carbon, makes about half of its own rainfall, and shelters roughly one in ten known species. Here is what a total loss would set in motion, and why the forest may not need to be fully cleared to fail.