In the mid 19th century whales were on the route to extinction. Albeit hunted for a very long time, whales had become the main source of the oil rich Americans used to illuminate their homes. Whaling rapidly rose to an industrial level, with a fleet of nearly 800 ships, taking a tremendous toll on the world’s biggest animals.

Thankfully, the cetacean species were spared by the almost concurrent invention of the kerosene lamp (in 1857) and the discovery of the first oil field in Pennsylvania (in 1859). Petroleum smelt better and did not spoil on the shelf, as whale oil did.

We now are at odds with what happened thereafter, when crude oil powered the most radical economic and social change in human history. Just today, the world will have consumed an average of 100 million barrels, or 15.9 billion litres. If we add other fossil fuel usage – coal and gas – we get the resulting emission of (a record) 37.1 billion tonnes of carbon dioxide spewed into the atmosphere last year. Oil saved the whales, yet it is endangering the entire planet.

Now, it turns out that we would be best off restoring whale populations to pre-whaling times. ‘When it comes to saving the planet,’ reads a recently published International Monetary Fund study, ‘one whale is worth thousands of trees.’ The equation is simple. Whales accumulate carbon in their bodies during their lifespan of 60 years. On average, each great whale sequesters 33 tons of CO2, which ends up at the bottom of the ocean when the animal dies.

But there’s more. Phytoplankton thrives on the iron and nitrogen found in cetacean excrements. ‘These microscopic creatures not only contribute at least 50 per cent of all oxygen to our atmosphere, they do so by capturing an estimated 40 per cent of all CO2 produced [by mankind],’ the study argues. In other words, having the original five million whales defecating in our oceans (instead of the current 1.3m) would be a blessing.

The IMF’s authors suggest an urgent world moratorium on whaling, to be compensated with international financial mechanisms. Emmanuel Macron said, at the (failed) UN Climate Summit in New York, that France will not strike trade deals with non climate-abiding countries. To be more effective, he should have told countries still engaging in whaling to simply stop killing the creatures.