It is one of the most magical sights in nature. Tail sailing: when the tail of a whale crests above the water. In 2022, photographers captured a humpback whale tail sailing off the coast of ZanzibarA group of islands off the coast of Tanzania. in the Indian Ocean. When scientists studied the whale's markings, they realised the same animal had been spotted before, 13,000km away, off the Pacific coast of Colombia.

How far is 13,000km? Well, imagine catching a train from Lisbon to Paris, and then another train from Paris to Moscow, and then a third train from Moscow to Beijing. And that's still only 12,868km!

But this is just the shortest distance between the two places where the whale was spotted. In reality, the animal would have taken a less direct route, meaning the journey was even longer. According to marine expert Dr Ekaterina Kalashnikova, it was "truly impressive and unusual even for this highly migratory species".¹

The journey was likely caused by climate change. Shortages in krill - the shrimp-like creatures that humpback whales feed on - have forced them to travel further in search of food. Alternatively, the whale may have been looking for new breeding grounds, as whale populations start rising again.

Humans have hunted whales since at least the Middle AgesThe Middle Ages was the period in European history that came between ancient and modern times. It lasted from about 500 to about 1500.. In the 19th and 20th Centuries, industrial fishing methods depleted their populations. By the 1960s, humans were hunting 80,000 whales a year and many breeds were facing extinction.

Commercial whaling was made illegal in the 1980s. Since then, whale populations have recovered, with added benefits for the environment.

Whales consume carbon-rich food, which they then store in their bodies. An average whale can capture 33 tonnes of carbon dioxide during one lifetime; by comparison, an oak tree captures just 12 tonnes over the course of its life.³

Whale poo is also a rich source of nutrients for phytoplanktonVery small plants that float near the surface of water. Sea creatures feed on them. . Together, these microscopic creatures capture 40% of carbon on the planet - the equivalent of 1.7 trillion trees.

But whales are still at risk. Some 300,000 whales, dolphins and porpoises die each year from being trapped in fishing gear. And whales near large cities ingest up to three million particles of microplastic a day.           

Humans are no longer hunting whales, but six out of 13 great whale species are classified as endangered or vulnerable. Warming polar regions also make it harder for them to find food.⁵

If whale populations can recover to historic levels, the benefit for the environment would be huge. A recent report by the IMFThe international Monetary Fund. Its main function has been to manage debt difficulties in many countries, often enforcing strict financial discipline in exchange for loans to governments. argued that whales were "irreplaceable in mitigating and building resilience to climate change".⁶

Repairing environmental damage is not the only reason to worry about whales. As the 13,000km journey shows, these are some of the most remarkable animals on the planet. Whether or not humans benefit from their survival, whales will benefit from protected habitats and restored populations. Surely this is reason enough to care.

Could these gentle giants save the planet?

Yes: Whales can capture 33 tonnes of carbon over the course of their life, as well as providing nutrients for phytoplankton. Restored whale populations are vital to climate resilience.

No: Whales remain at risk from busy shipping lanes, intensive fishing and water pollution. Rebounding populations are good news, but more must be done to protect these animals.

Or... Restoring whale populations will not reverse all the damage humans have done to the environment. But this one whale's 13,000km journey shows why we should still care about protecting them.

Zanzibar - A group of islands off the coast of Tanzania.

Middle Ages - The Middle Ages was the period in European history that came between ancient and modern times. It lasted from about 500 to about 1500.

Phytoplankton - Very small plants that float near the surface of water. Sea creatures feed on them.

IMF - The international Monetary Fund. Its main function has been to manage debt difficulties in many countries, often enforcing strict financial discipline in exchange for loans to governments.