Sperm whales may put a gentle (and unwitting) brake on climate change

Sperm whale faeces may help oceans absorb carbon dioxide from the air, scientists say.

Australian researchers calculate that Southern Ocean sperm whales release about 50 tonnes of iron every year.

This stimulates the growth of tiny marine plants – phytoplankton – which absorb CO2 during photosynthesis.

The process results in the absorption of about 400,000 tonnes of carbon – more than twice as much as the whales release by breathing, the study says.

The researchers note in the Royal Society journal Proceedings B that the process also provides more food for the whales, estimated to number about 12,000.

Phytoplankton are the basis of the marine food web in this part of the world, and the growth of these tiny plants is limited by the amount of nutrients available, including iron.
Faecal attraction

Over the last decade or so, many groups of scientists have experimented with putting iron into the oceans deliberately as a ‘fix’ for climate change.

Not all of these experiments have proved successful; the biggest, the German Lohafex expedition, put six tonnes of iron into the Southern Ocean in 2008, but saw no sustained increase in carbon uptake.
The Polarstern The Lohafex expedition was […]