Living organisms are a great place to store carbon. Trees are the most common organisms to be used as carbon sinks, but other things might be even better. Whales are particularly good for this because they are large—blue whales are the largest animals on Earth—and when they die, they sink to the bottom of the ocean taking the carbon with them and keeping it out of the atmosphere where it would contribute to climate change.
Killing those whales, though, prevents all that carbon from being stored at the bottom of the ocean, whether the whale is turned into lamp oil, as it was a hundred years ago, or consumed as dinner, like in Japan today.
University of Maine marine scientist Andrew Pershing calculated that about 110 million tons of carbon has been released from the past 100 years of whaling (not counting the emissions from the boats used to hunt the whales). And while there are far bigger sources of carbon, such as our cars, whaling has released about as much carbon as deforesting much of New England would.
There has been some discussion lately of discontinuing the ban on commercial whaling (a ban that Japan, Iceland and Norway already ignore). The value of whales as a carbon sink, though, is a new enough idea that it hasn't yet made it into those talks. But Pershing suggested at a recent scientific meeting that a system of carbon credits could be developed to raise funds to protect whales and other large oceanic predators. As he explained to BBC News, "These are huge and they are top predators, so unless they're fished they would be likely to take their biomass to the bottom of the ocean."