Why saving sperm whales is more important than ever

When the International Whaling Commission meets in Morocco next week to discuss lifting the moratorium on commercial whaling, delegates might pause to consider an unexpected fact: the faeces of sperm whales is helping to save the planet.

Australian researchers have found that the iron-rich faeces of sperm whales living in the Southern Ocean boosts the growth of phytoplankton, marine plants which suck in carbon dioxide from the atmosphere. They estimate that the whales are responsible for removing 400,000 tonnes of carbon each year, twice as much as they contribute through respiration.

According to the scientists, based at Adelaide's Flinders University, they would be disposing of 10 times as much carbon were it not for commercial whaling. Their faeces is useful because it is emitted in liquid form close to the surface of the ocean, where phytoplankton is found, according to the study, published in the journal Proceedings of the Royal Society B: Biological Sciences.

Trish Lavery, the lead researcher, based at the university's School of Biological Sciences, estimates that each of the Southern Ocean's approximately 12,000 sperm whales releases about 50 tonnes of iron into the sea annually.

Previously, the enormous mammals were regarded as climate criminals because they breathe out carbon dioxide. But Ms Lavery concluded that they are a major carbon absorbent, removing the equivalent of the emissions of 40,000 cars each year.

She said: "They have certainly gone past the carbon-neutral status that we all aspire to, and they're actually sinking more carbon from the atmosphere each year into the deep ocean... than what they add to the atmosphere.

"If we hadn't decreased sperm whale populations from their historical levels, we'd have an extra about two million tonnes of carbon being pulled out of our atmosphere every year."