Whales and climate change: what’s the connection?

Way below the ocean surface, some 2,000 meters into its depths, is where you’ll find whales. These mammals are impressive in size – they can reach 30 meters in length and 200 tons. Whales roam every ocean and are excellent communicators, using mysterious sounds that cross vast kilometres. The immensity of the oceans and the migratory nature of whales makes studying these animals extremely challenging.

The various species of whales can be divided into two large groups:

• Toothed whales (Odontoceti)

  These whales have teeth and are generally active predators. The two best-known species are the sperm whale (physeter macrocephalus), famous for its spermaceti, a fatty, waxy substance produced in cavities in their heads that helps focus sound, and the orca (orcinus orca), which stands out for its black and white colour pattern, intelligence and sociability.

• Baleen whales (Mysticeti)

  Instead of teeth, this type of whale filters food through keratin plates (baleen). This group includes the blue whale (balaenoptera musculus), the largest animal on the planet, and the humpback whale (megaptera novaeangliae), known for its acrobatic leaps and mysterious songs.

Like any other mammal, whales breathe air (which is why they come to the surface), lactate their young and have warm blood. They have a thick layer of blubber that protects them from cold waters; however, they cannot protect themselves from every threat and the conservation status of some species, such as the blue whale, is “Endangered”.

There is another fact whose importance is as great as these beings: whales play a crucial role in balancing the ecosystem and regulating the planet’s climate.

One of the most fascinating functions of whales is their ability to capture carbon from the atmosphere – something essential in the fight against climate change.

Whales are responsible for capturing and storing carbon in the following ways:

1. Nutrient migration

   Whales make some of the longest migrations on the planet, which can reach around 20,000 kilometres. They move from nutrient-rich feeding grounds to breeding areas with fewer nutrients, where they mate and give birth. During these migrations, whales expel the nutrients consumed in the form of faeces and urine, both along the migratory routes and in the breeding areas. Whale faeces are rich in nutrients, such as iron, essential for the growth of phytoplankton. Besides being responsible for around 50% of the planet’s oxygen production, phytoplankton is a food source for many other marine species and absorbs large amounts of carbon dioxide during photosynthesis. When phytoplankton die, some of the carbon they have absorbed is stored at the bottom of the sea.

2. Vertical movement

   Whales move between different water columns, from the depths of the ocean to the surface and vice versa. This behaviour helps to mix the waters, which contributes to a good circulation of nutrients and stimulates phytoplankton growth. It also moves carbon from the ocean’s surface to its depths, a cycle that helps regulate the planet’s climate.

3. Whale biomass

   Throughout their lives, whales accumulate a huge amount of carbon in their bodies. When they die, they sink into the ocean, taking this carbon with them. It is a phenomenon known as “whale fall” and allows carbon to be stored for hundreds to thousands of years, which helps to keep carbon dioxide levels in the atmosphere lower.

Many of the threats whales face are the result of human activities. Learn more about them.

Commercial capture and illegal hunting

At the beginning of the 19th century, began a period of whale hunting that lasted several years, with the aim of obtaining meat, blubber, fins and other by-products. Whale oil was extremely valuable, used to light streets and houses, as a lubricant or in the production of soap, candles and margarine – a commercial activity that led to the endangerment of the species.

It wasn’t until 1986, almost two centuries later, that the International Whaling Commission (IWC) was created, which implemented a global moratorium on commercial whaling to allow the species to recover. Portugal became an international example by being one of the first countries to voluntarily ban whaling in the early 80s.

In the 1930s, whale catching fuelled the economies of the Azores and Madeira; on the mainland, hunting took place between São Vicente and Cape Carvoeiro, in the western region. Everything changed when the country decided to ban whaling – in 1981 in Madeira and 1984 in the Azores. However, 40 years later, things have changed and observing giant cetaceans in their natural environment is one of the most important tourist activities.

Despite the changes to the law, some countries, such as Japan, continue to practice commercial whaling, claiming scientific or cultural purposes.

Marine pollution

Plastics – and microplastics – also “inhabit” the oceans and, whether through accidental ingestion, contact with toxic chemicals in the waters, or by being trapped or strangled in plastic, whales and other marine creatures suffer the consequences. Pesticides, herbicides, industrial pollutants and heavy metals such as mercury and lead can also end up in the oceans, contaminating the marine food chain.

Climate change

Climate change and global warming have an impact on the aquatic world, making waters warmer and more acidic and influencing migratory flows. These factors affect the whales’ diet, as their prey moves to other areas, and their reproduction levels. Sea acidification also has an impact on coral reefs and the available phytoplankton.

Despite the threats they face, there are small gestures we can all take to help protect whales and marine ecosystems.

1. Reduce the use of plastics, favour reusable products and recycle.
2. Join beach clean-ups to remove waste from the marine environment.
3. Put chemicals to a safe use to prevent them from ending up in the oceans.
4. Travel responsibly and support tour operators who follow sustainable practices with marine animals.
5. Include small actions in our daily lives to reduce our ecological footprint, such as saving water, electricity and gas at home.
6. Support organizations that protect whales and the oceans through donations or volunteering.

• It is estimated that there are currently around 1.3 million whales – before the era of whaling, that figure was around 4 to 5 million;
• The blue whale is the largest known animal to have ever existed on Earth. It can reach 30 meters in length and weigh up to 200 tons;
• Some whale species live surprisingly long lives, up to 200 years;
• Whales turn off half their brain to sleep (the other half has to stay “awake” in order to remember to go to the surface to breathe) and, to rest the entire brain, they just switch the “sleeping” side;
• Whales’ diet includes squid, octopus, crab and small fish;
• The Azores is one of the largest whale sanctuaries in the world and one of the best places for whale watching;
• Whales can hold their breath underwater for long periods, which vary depending on the species – the Cuvier’s beaked whale made the longest dive ever recorded, lasting 222 minutes, or almost four hours.