In a joint project backed by the University of Maine, US, and
Gulf of Maine Research Institute, Pershing compared whales to
redwood trees as a store of carbon. Blue whales contain around nine
tons of carbon; in the biological world, only large trees can store
more than this. Using this analogy, whaling becomes equivalent to a
forest fire, potentially releasing carbon dioxide to the atmosphere
or "at the very least, removing it from the marine environment and
putting it somewhere else," Pershing told a press conference at the
AGU Ocean Sciences Meeting in Portland, US.
Populations of whales, it turns out, are in some ways better at
storing carbon than forests. Once a forest has finished growing or
regenerating and reached a steady state it tends not to store any
additional carbon - each tree that dies and releases its carbon to
the atmosphere is replaced by another. But the bodies of whales
that die naturally tend to sink to the ocean floor. If the whale
dies in a deep area of ocean the carbon from its body could remain
locked away for a couple of hundred years.
Whaling, on the other hand, has in the past led to use of the
whale's body parts in products, such as lamp oil and animal feed.
This probably enabled an earlier release of carbon to the
atmosphere. Even if the entire whale was not removed from the
ocean, its hacked-up remains were likely to have been consumed by
smaller organisms in surface waters, rather than sinking to the
depths. This would again have led to quicker recycling of the
Pershing calculated that one hundred years of whaling have added
105 million tonnes of carbon to the atmosphere. This is
equivalent to the carbon released by burning 130,000 sq km of
temperate forest or by 128,000 Hummers driving for
100 years. To perform the sums, Pershing assumed that all the
carbon in a whale killed by humans is released to the
Although the carbon released by whaling is just a small fraction
of the 7 billion tonnes that man emitted in 2005, Pershing
says it is comparable to the amount that would be saved by other
proposed carbon management and storage schemes. "Whales were the
oil of the 1700s and 1800s," he added.
Not everyone agrees that killing whales has affected
the level of carbon dioxide in the Earth's atmosphere. "It is
obvious that the dramatic decrease in the whale populations has
greatly altered the world's ocean ecosystem. However, I don't think
that whale hunting has had any major impact on the level of carbon
dioxide in the Earth's atmosphere," said Vasily Spiridonov, a
consultant of the Marine Program of the World Wildlife Fund
Having compared whales to trees, Pershing also introduced
poodles to illustrate that larger animals are more efficient at
storing carbon. Zelda, his wife's 6 pound toy poodle, eats one
cup of food a day. His standard poodle Padawan, meanwhile, which is
ten times heavier than Zelda, eats just five cups of food per day.
So Padawan is using relatively less carbon, in the form of food, to
store the carbon already in his body.
Because of this greater efficiency of larger animals, Pershing
says his findings provide an incentive to focus on conserving large
species of marine organisms, such as whales, sharks and tuna.
Populations of some of these animals and fish are down by 90% or
For the same reason it makes sense to focus on large individuals
of each species. In the case of fish, large individuals also tend
to produce more eggs, so this approach should increase the
population's recovery rate.