Whales, with a scientific name of Cetacea, are a widespread and diverse group of entirely aquatic placental marine mammals. There are two groups of whales: baleen (Mysticeti) whales and toothed (Odontoceti) whales. There are four families of Mysticetes: the rorquals, right whales, the pygmy right whale, and the grey whale. Within the Odontocetes are belugas and narwhals, the sperm whale, the dwarf and pygmy sperm whale, and the beaked whales.
Whales are offshore animals. They feed, mate, give birth, suckle, and raise their offspring at sea. The smallest whales measure 2.6 meters and weigh approximately 135 kilograms. The biggest one is the blue whale, which can weigh 190 tons and is 29.9 meters long. That is also, knowingly, the largest animal that has ever lived. Baleen whales don’t have teeth. They have something called baleen. It is a fringe-like structure that allows them to discharge a huge amount of water from their mouth while they keep inside the krill and plankton they feed on. Their heads are massive—around 40% of their body mass—and since they have throat folds that allow them to expand their moths, they are able to swallow a huge amount of water at a time. Toothed whales have conic teeth, which are perfect for catching fish, seals, and squid. They also have super good hearing, and they can hear above and below the surface of the water. Since whales evolved from land-living animals, they have to come to the surface to breathe air. Whales have modified nostrils or blowholes on top of their heads. Through them, they breathe. Whales are warm-blooded. Under the skin, they have a layer of fat or blubber. Whales are also known for the sound they make underwater, especially the humpback whales. Whales prefer colder water, and they migrate closer to the equator to give birth.

Whales are big and mythical animals, but unfortunately, almost half of the species are endangered or vulnerable. Around 300,000 whales and dolphins are killed every year because of fisheries by catch, shipping, climate change, loss of food, diseases, and habitat loss. The most dangered species of whale is the North Atlantic whale, with only 400 left. The others range from 10 000 to 90 000 individuals.
In the past, it was hard to tell the threat to the whales, the reason being that there wasn’t just enough knowledge about these mammals. Nowadays, there are around 1.3 million whales. The number used to be 4 to 5 million. One of the reason why whales are endangered is the commercial whaling. In most of country’s it is strictly forbidden. The other reason is that the world’s busiest shipping lanes are similar to the areas where whales feed, birth, nurse, or travel between feeding and breeding areas. Clashes with ships, by-catch, and pollution injure and kill the whales. There’s also noise pollution. It disturbs whale communication or can even damage their hearing.
Internationally, the sale of whale products is forbidden, but there are still three countries that allow it: Iceland, Norway, and Japan. Because of this, over 1000 whales are killed every year.
Global warming is also affecting whales through warming oceans and habitat loss. Most likely, the number of plankton (both phyto and zoo) will change because climate change affects the seawater temperature, winds, and ocean currents. That can mean that blue and humpback whales, which feed on plankton, have to migrate more, and therefore they don’t have enough time to search food. Because of climate change, the North Atlantic whales are endangered, and their reproductive rates are also low.

Scientists have discovered that great whales, for example, baleen whales and sperm whales, can capture a large amount of carbon dioxide from the atmosphere. One whale is able to capture more CO2 than thousands of trees could.
As already said, the biggest whales feed on plankton. Phytoplankton captures CO2 from the atmosphere, and it also produces 50% of the oxygen. By producing the oxygen, they have to capture CO2, and they capture around 37 billion metric tons every year. Scientists have noticed that wherever whales are, phytoplankton is also there. They have discovered that the waste of whales contains iron and nitrogen, and these are needed for phytoplankton to grow. Whales also bring minerals to the surface of the ocean by their vertical movement. This is called the ‘whale pump’.
Whales also absorb carbon in their bodies. Some whales can live around one hundred years. When they die, their body sinks to the bottom of the ocean. That means that the carbon in their body is also settled at the bottom of the ocean. When land animals die, the carbon from their bodies is released back into the atmosphere. It can take up to 1000 years before the carbon from a whale’s body reaches the surface. This phenomenon is known as ‘blue carbon’.

In conclusion, whales are on top of the food chain. They have an important role to play in the overall health of the marine environment. Whales are important for fixing carbon dioxide in the atmosphere. On average, each bigger whale fixes around 33 tons of CO2, contributing to the fight against climate change. At the same time, trees absorb only 56 kg of CO2. So maybe protecting the whales will help us fight climate change.

Sources:
https://en.wikipedia.org/wiki/Whale
https://www.worldwildlife.org/species/whale
https://www.nationalgeographic.com/animals/mammals/facts/whale-facts
https://iwc.int/management-and-conservation/environment/climate-change
https://www.worldwildlife.org/stories/what-makes-whales-fin-tastic-climate-champions
https://savethewhales.org/threatened-and-endagered/
https://www.imf.org/en/Publications/fandd/issues/2019/12/natures-solution-to-climate-change-chami