Whaling and climate change

Definition

Whales are marine mammals that occur in all the world’s oceans. They belong to the Order Cetacea, along with dolphins and porpoises. Although all cetaceans may be considered whales, the term “whales” traditionally refers to the members of this order that exceed 6 meters (20 feet) in length. These include the baleen whales, such as the blue whale and right whale, sperm whales, pilot whales, and killer whales.

Whales include the largest animals ever to exist. The mass of a blue whale, for example, is several times greater than that of the largest dinosaur known. Despite their fish-like appearance, whales are air-breathing mammals that have hair and mammary glands like other mammals and must come to the surface to breathe. Their ancestors, 50 million years ago, were hippopotamus-like creatures distantly related to modern hippos. Modern whales form two distinct groups, the baleen whales (Mysticetes)—also known as the rorquals—that feed on krill and the toothed whales (Odontocetes)—such as the sperm whales, dolphins, and porpoises—that feed on fish and larger marine invertebrates.

All the world’s whales are carnivores, and therefore many of the great whales are migratory, spending summer months in colder polar waters where food is plentiful and then returning to more tropical or subtropical waters to winter and spawn their calves. California gray whales, for example, feed along the northern pack ice of the Arctic but winter in warmer lagoon waters off Baja, California. Their twice-annual seasonal migrations northward along the California coast provide a popular pastime for wildlife enthusiasts, who line the shores to spot these leviathans on their migratory journeys.

Significance for Climate Change

Whaling is the commercial harvesting of whales for food, blubber, oil, whalebone, and other products. Whaling is a centuries-old industry that probably began when Indigenous peoples harvested beached whales for food. Commercial whaling began with the Basques of northern Spain and the people of the Azores Islands, who pursued slower whales such as the right whale. The activity soon spread across Europe. By the nineteenth and twentieth centuries, whaling ships regularly departed from ports in New England, Iceland, Norway, the Netherlands, and other locales for Arctic and Antarctic waters of the Pacific on cruises that lasted many years.

Commercial whaling reached its peak following World War II, when whaling fleets accompanied by floating whale processing factories took to the seas to harvest record numbers of whales. The whale slaughter that resulted from this efficient combination greatly exceeded the recruitment ability of major whaling stocks, and many of the largest whales, including blue, fin, sei, and sperm whales, drastically declined under this onslaught. In response, the United Nations declared a moratorium on whaling and whale products, and many other nations followed suit. Some countries, such as Japan and Russia, continued whaling activities but on a much-reduced scale. Following the curtailment of high-seas commercial whaling, most whale populations slowly began to recover; however, the threats posed by global warming continued to jeopardize the population stability of many great whales.

The higher temperatures and greater rainfall associated with global climate change are warming surface seawaters and hastening the melting of the Arctic and Antarctic pack ice and of the Greenland glacier, all of which result in changes in icy polar habitats and the food supply of most of the world’s whales. In the Arctic, the rapid melting of the ice cover threatens stocks of northern whales such as the narwhale, beluga, and bowhead whales, as well as gray whales that feed in these waters during the summer. Rainwater, along with water from the melting ice, dilutes seawater, sharply reducing its salinity and destroying the populations of marine organisms on which these northern whales depend.

Gray whales returning to their wintering grounds off Baja, California, to breed appear underfed, and their breeding success has declined. Furthermore, the melting of the Arctic ice cover awakened prospects for the development of northern sea trade routes and the exploitation of resources that underlie the ocean floor. Russia, Canada, and the United States have expressed interest in petroleum deposits on their respective continental shelves as the Arctic pack ice melts. Increased trafficking associated with exploration and economic development, such as commercial shipping, mining, and oil extraction, poses a major threat to the fragile Arctic habitat and its cetacean inhabitants.

At the other end of the Earth, rapid melting of Antarctic pack ice threatens southern baleen whales that gather to feed in these once krill-rich waters. Krill feed on plankton populations that grow beneath the pack ice and that are disappearing as rapidly as the melting ice. Lack of plankton causes loss of krill, forcing baleen whales northward into warmer subtropical water in desperate search for food that is not there. The lack of krill also results in loss of life-sustaining blubber, increasing susceptibility to both disease and starvation. Overall, the combination of these climate change factors may lead to the loss of the largest animals ever to exist.

In mid-2017, at least ten endangered North Atlantic right whales were found dead off the eastern coast of Canada or along its shores. This discovery was especially disconcerting for conservationists, as the North Atlantic right whale population was already particularly low; additionally, this rate of deaths was higher than average in such a short time, making 2017 the worst year for the whales' mortality in decades. Both US and Canadian authorities began planning methods for establishing the cause of so many deaths, with early speculation focusing on ship strikes and entanglements in fishing gear. Further research would also be conducted to determine whether the whales had been moving north from their typical summer habitats to find greater sources of prey that had also moved in search of cooler waters due to global warming.

During the 2010s and 2020s, the impacts of global climate change began to intensify across the Earth, resulting in negative effects on whale populations. Reduced sea ice levels made it more difficult for North Pacific right whales to find and feed on zooplankton, restricting their food sources and leading to diminished reproduction. Unpredictable changes in sea ice also interfered with the migration patterns of Beluga Whales, making it difficult for endangered populations to recover.

Whales play a critical role in ecosystems by acting as natural carbon sinks. A 2019 report by the International Monetary Fund (IMF) assessed the monetary equivalence of their role and reported that each whale sequesters around 33 tons of carbon annually. It takes approximately 30,000 trees to reach this level of carbon sequestration. The IMF estimated an average annual value of $2 million per whale. Similarly emphasizing the importance of whales, the 2022 Sixth Assessment Report of the International Panel on Climate Change suggested these animals as potential blue carbon ecosystems.

Bibliography

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Mychajliw, Alexis M., and Thomas A. Jefferson. “Marine Mammals: Exploited for Millennia, but Still Holding On.” The Living Planet: The State of the World’s Wildlife, edited by Norman Maclean, Cambridge UP, 2023, pp. 87–105.

Stokstad, Erik. "Endangered Right Whales Are Dying in Record Numbers off Canada, Raising Alarm." Science, 24 Aug. 2017, www.sciencemag.org/news/2017/08/endangered-right-whales-are-dying-record-numbers-canada-raising-alarm. Accessed 16 Sept. 2025.

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