The mammals accumulate carbon in their bodies throughout their long lives, with some species living for up to 90 years, and then when they die they take that carbon to the bottom of the ocean, where it is stored for centuries.
Each whale can lock almost 30,000 kilograms of carbon dioxide on average out of the atmosphere. A tree, meanwhile, absorbs only up to 21 kilograms of carbon dioxide a year.
As well as this, whales also support the production of phytoplankton, which contributes at least 50 per cent of all oxygen to the Earth’s atmosphere and captures as much carbon dioxide as 1.7 trillion trees, or four Amazon forests.
They do this as when they swim up to the surface from deep waters, their large bodies move nutrients up with them. Bringing nutrients to the surface increases the food source for the tiny but crucial organisms.
Whales bring minerals up to the ocean surface through their vertical movement, called the “whale pump,” and through their migration across oceans, called the “whale conveyor belt".
Increasing phytoplankton productivity by just 1 per cent would have the same effect as the sudden appearance of 2 billion mature trees, according to the study.
Ralph Chami and Sena Oztosun from the IMF’s Institute for Capacity Development, along with professors from Duke University and the University of Notre Dame said increasing whale populations “could lead to a breakthrough in the fight against climate change.”