Blue whale over water

How whales can help reduce global warming

June 30 2021

Apart from wildlife preservation, protecting whales has another interesting benefit for the Earth’s ecosystem. It can help control climate change by limiting greenhouse gases and therefore reducing carbon imprint (the amount of carbon dioxide released into the atmosphere). Many of the solutions proposed to fight global warming are too complex or have high costs, however increasing the global whale population may end up being a good solution, effectively and economically.

During the 16th century, the appearance of new technological improvements allowed whaling to become a global trade. In 1964 biologists warned about whale populations being in risk of extinction in the southern hemisphere, with only 2000 blue whales remaining. By 1974, the blue whale was about to be extinct, with only 360 specimens left.

In 1986 a worldwide ban on whaling was imposed by the International Whaling Committee and since then, whale population has slightly recovered (numbers for the Antarctic blue whale reached 3000 in 2018).



The role of whales in carbon sequestration

Carbon sequestration is described as the process by which carbon dioxide is removed from the atmosphere and held in solid or liquid form. Whales stock tons of carbon in their fat and protein-rich bodies during their lives. When they reach death, their body sinks into the deep ocean floor transferring all the carbon they had stored over the years, where it will remain for centuries. So instead of carbon being released into the atmosphere, whales attract big amounts of carbon during their lives and then bury it at the bottom of the ocean.

A study in 2010 stated that whales would have sunk between 190,000 to 1.9 million tonnes of carbon per year to the bottom of the ocean before commercial whaling started.





A chain of events

A decrease in global whale population not only affects carbon sequestration, it has other negative impacts too. They are valuable after they die, but also during their life. Whale waste is actually very relevant to fight climate change.

Whales feed themselves in the deep ocean, but they return to the surface to breathe and release waste. Their excrement is rich in iron and nitrogen which are key substances for the growth of phytoplankton. These microscopic creatures have a huge impact on the Earth’s atmosphere. They capture 40% of all carbon dioxide that is produced, which is actually four times the amount that the Amazon rainforest captures. They also produce 70% of the oxygen we breathe, so they are a very important piece of the puzzle.

Another negative effect of the decrease in whale population is related to the food chain. With whale numbers on the decline, orcas (their natural predator) started to prey on smaller mammals like sea otters. This led to sea otter numbers declining, which then led to sea urchins spreading and devastating kelp forests (kelp are large brown algae that live in cool, relatively shallow waters close to the shore). This ultimately had a negative effect on marine carbon sequestration.



The human impact

Over history, humans have been the biggest predator of whales. They have been killed for centuries for their meat, oil or whalebone (a series of stiff keratinous plates which grow in the upper jaw of some whales and is used by them to strain plankton from the seawater).

The exact number is uncertain, but whale population may have declined between 66% and 90%. According to biologist estimates, commercial whaling has left less than one fourth of the whale population that once existed, with some species like the blue whale having only 3% of their previous numbers left alive.

But commercial whaling is not the only hazard that humans present. Plastic waste, fishing nets, ship trikes or noise pollution are other threats that humankind puts on marine wildlife.



Breaking down the numbers

To get a better understanding of the impact whale preservation can have on global warming, here are some numbers:

A tree can absorb up to 22 kilos of CO2 per year. Meanwhile, a whale can averagely sequester 33 tons of CO2, removing that carbon from the atmosphere for centuries.

Commercial whaling released 70 million tons of CO2 into the atmosphere during the 20th Century.





Increasing phytoplankton by 1% thanks to whale preservation would allow millions of tons of additional CO2 to be captured per year, the equivalent to 2 billion trees.

In 2019, a report was published by the International Monetary Fund (IMF) trying to showcase the benefits of whale preservation by adding a dollar value to it.

The study concludes that the value of the carbon a whale can sequester in its lifetime together with other benefits like increased ecotourism or better fisheries adds up to more than 2 million dollars, with the global stock adding over 1 trillion dollars. A project is currently being worked on by economists to turn this from theory into reality. This would be done with carbon offsetting, which is a process by which carbon emitters pay to protect whale populations instead of investing in reducing their own carbon emissions.


Although whale population restoration is not a fix-all solution to global warming, it could be an important tool to help reduce climate change. Even though it would have an impact on the huge amount of carbon dioxide released by fossil fuels, further action needs to be taken. It would take an estimate of 30 years to double the current whale population and generations to reach the numbers that existed before commercial whaling was in full effect.





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