Great whales absorb large amounts of carbon dioxide, much more than trees do. A new study from the International Monetary Fund suggests climate activists should focus on increasing the number of whales in their efforts to save the planet. (Michael Dwyer/AP)

Climate activists would be better off trying to save whales rather than planting trees if they had to choose between those options, according to a new study published by the International Monetary Fund (IMF).

Great whales are the carbon-capture titans of the animal world, each absorbing an average of 33 tons of carbon dioxide, or CO2, throughout their lives before their bodies sink to the bottom of the ocean and remain there for centuries, according an article in the December issue of the organization’s Finance and Development Magazine. A tree, by contrast, absorbs no more than 48 pounds of the gas a year.

That difference prompted Ralph Chami and Sena Oztosun from the IMF’s Institute for Capacity Development, and two professors, Thomas Cosimano and Connel Fullenkamp, to argue that supporting international efforts to restore whale populations — which have fallen from about 4 million to 1.3 million after years of commercial hunting — “could lead to a breakthrough in the fight against climate change.”

The researchers urged countries that signed the Paris agreement on climate change to work together on protecting whales.

In addition to binding significant amounts of CO2 themselves, whales also support the production of phytoplankton (pronounced FI-toe-plank-ton), which contributes at least 50 percent of all oxygen to the Earth’s atmosphere and captures as much CO2 as 1.7 trillion trees, or four Amazon forests.

Increasing phytoplankton productivity by just 1 percent would have the same effect as the sudden appearance of 2 billion mature trees, according to the study.