New research from a pair of scientists at the excellently-named
Flinders University in Australia reveals that sperm whales are
actually able to offset their own carbon emissions. Like all
mammals, sperm whales take in oxygen and turn it into carbon
dioxide, but it turns out that the creatures also defecate iron-
rich nutrients which stimulate phytoplankton growth. That extra
phytoplankton, which wouldn't otherwise exist due to the natural
lack of iron in the Southern Ocean, takes carbon dioxide out of
the atmosphere and replaces it with oxygen during
photosynthesis. The carbon sinks to the bottom of the ocean when
the phytoplankton dies, removing it from the atmosphere for
millennia and eventually -- under the right conditions --
becoming oil. Trish Lavery and Jim Mitchell reckon that the
whale population in the Southern Ocean, which numbers around
12,000, defecates around 50 tonnes of iron per year into the
photic zone - the zone in the upper regions of the ocean where
there's enough light for photosynthesis