While trees may be the best nature-based terrestrial solution to capturing carbon from human emissions, a new report shows that the ocean has its own gentle giants with an incredible potential to combat climate change — whales.

According to the report, published by the International Monetary Fund, great whales are the carbon-capture titans of the animal world, absorbing an average of 33 tons of CO2 each throughout their lives before their carcasses sink to the bottom of the ocean and remain there for centuries. A tree, by contrast, absorbs no more than 48 pounds of the gas a year.

In addition to binding significant amounts of CO2 themselves, whales also support the production of phytoplankton. These tiny creatures produce every second breath we take, by contributing to at least 50 percent of all the oxygen in our atmosphere. They also capture about 37 billion tons of carbon dioxide or four Amazon forests’ worth. 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.

The researchers argue that if the whale population was allowed to grow to around 4 to 5 million — the total before the era of whaling — the mammals would be able to capture 1.7 billion tons of CO2 annually.

Overall, the report aims at highlighting the urgent need to support international efforts of protecting and raising the numbers of these magnificent leviathans, which are currently under significant man-made threats, including ship strikes, entanglement in fishing nets, waterborne plastic waste, and noise pollution.