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To fight climate change, save the whales, some scientists say

  • In death, whales carry the tons of carbon stored in their massive bodies down to rest on the seafloor, where it can remain for centuries.
  • Whale excrement fertilizes the ocean, producing large phytoplankton blooms that absorb enormous amounts of carbon dioxide.
  • Scientists point out that helping whale populations recover from past overharvesting can help reduce greenhouse gas levels in the atmosphere.

Science has established the urgency of reducing carbon dioxide emissions into the atmosphere. If humans do not reduce greenhouse gas emissions by 45% from 2010 levels in the next nine years and eliminate them completely by 2050, the planet’s temperature will rise to 1.5° Celsius (2.7° Fahrenheit) above that of the pre-industrial period. This would have far-reaching effects on ecosystems and on humankind’s ways of life — effects that are already beginning to unfold.

The conservation of whales plays a key role in the race to stop this planetary crisis, some scientists say. “Contrary to most terrestrial organisms, which release their carbon into the atmosphere after death, carcasses of large marine fish sink and sequester carbon in the deep ocean,” according to the authors of a study published last October in the journal Science Advances. This is an example of what’s known as “blue carbon,” and the principle applies to whales as much as to fish.

Image courtesy of Patagonia PhotoSafaris.

For decades, a large portion of this blue carbon, instead of coming to eternal rest on the ocean floor, has been released into the atmosphere as a result of people capturing excessive numbers of fish and whales.

According to the study, fisheries have released at least 730 million tons of carbon dioxide into the atmosphere since 1950, about the same amount as 188 coal-fired power plants release in a year. These emissions come from the release of carbon in fish bodies into the air when they’re eaten or disposed of on land instead of in the sea, and from vessels’ fuel consumption, and they contribute significantly to global warming and climate change.

The figure accounts for the capture of large-bodied fish, including tunas, mackerels, billfish and sharks, that typically sink when they die of natural causes. It does not, however, account for the biggest-bodied creatures in the sea and therefore the ones that store the most carbon: whales.

When whales die of natural causes, “their bodies, which are gigantic and which have captured carbon during their lives, fall to the bottom of the sea, keeping carbon dioxide on the ocean floor,” said Elsa Cabrera, executive director of the Cetacean Conservation Center in Chile, who was not involved in the study.

A 2019 report in the magazine of the International Monetary Fund (IMF) stated that “each great whale sequesters 33 tons of CO2 on average, taking that carbon out of the atmosphere for centuries.” Rebuilding populations of large baleen whales would store carbon in their bodies equivalent to the amount in 110,000 hectares (272,000 acres) of forest, “an area the size of the Rocky Mountain National Park,” in Colorado, U.S., the authors of a 2010 paper in PLOS ONE calculated.

This is why whales are “an extremely powerful ally in the fight against the climate crisis,” Cabrera said.

Whales still being hunted

According to the Science Advances study, 43.5% of the blue carbon extracted by fisheries in international waters comes from areas that would not be profitable to fish in without governments subsidizing the fisheries that operate there.

Many scientists and conservationists say fishing subsidies are one of the main drivers of the overexploitation of marine resources. “It is very important to reach an agreement to stop them,” said Alex Muñoz, the director of National Geographic’s Pristine Seas program for Latin America.

The international community has been attempting do just that for 20 years, with talks at the World Trade Organization missing the latest deadline to reach an agreement at the end of 2020. Negotiations resumed early this year but numerous large sticking points remain.

The study provides more reasons to end subsidies for fishing that occurs far offshore. Doing so would curtail fishing in unprofitable areas, not only allowing depleted fish stocks to rebound but also reducing carbon dioxide emissions, according to the study.

A similar logic applies to whaling, Cabrera said. “In this sense … Japan has a very dark record regarding whales, because with the number that it has helped to capture through state subsidies, it is responsible for a large loss of these animals from the ocean, even though they are key allies,” said Cabrera, who is an accredited observer in meetings held by the International Whaling Commission (IWC), the international body that manages whale conservation and regulates whale hunting.

The NGO Greenpeace’s inflatable boats try to obstruct the transfer of a dead minke whale from a Japanese whaling ship to a processing ship, circa 2005. Image by Jeremy Sutton-Hibbert/Greenpeace.

On June 29, 2019, Japan exited the IWC so it could restart commercial whale hunting in its maritime territory after a 31-year hiatus. It did so immediately, by July 1 of that year. For 2020, the number of large whales it could capture — within Japanese waters only — was 171 minke whales (Balaenoptera acutorostrata), 187 Bryde’s whales (Balaenoptera edeni) and 25 sei whales (Balaenoptera borealis), according to the Ministry of Foreign Affairs website. The numbers for 2021 are reportedly the same.

Prior to withdrawing from the IWC, Japan conducted a controversial whale hunt for what it called scientific purposes under two different programs. One was in the Southern Ocean around Antarctica and involved the capture of minke whales; the other was in the North Pacific Ocean and involved the capture of minke, Bryde’s and sei whales. Japan was killing about 600 whales per year under the programs, according to IWC figures.

Japan argued that the objective of these studies was to collect information necessary to give future commercial whaling a scientific basis. However, critics said Japan’s whale hunt never had scientific objectives. “This was never an issue of science,” Cabrera said.

This was evident in 2014, she said, when the International Court of Justice ruled against Japan in a lawsuit filed by Australia and New Zealand. “The special permits granted by Japan for the killing, taking, and treating of whales in connection with JARPA II [the Antarctic program] were not ‘for purposes of scientific research,’” the court ruling stated.

A blue whale. Image courtesy of the Cetacean Conservation Center.

In addition to Japan, Norway and Iceland are the two other countries that currently allow commercial whaling. However, some scientists believe the days of whaling are numbered. While Norwegian whalers are going strong, Iceland hunted no whales in 2019 and 2020, apparently due to financial decisions by the country’s two main whaling companies. According to a July 2019 article in The New York Times, “The [Japanese] government also hopes to start reducing the $46 million in annual subsidies it pays to whale hunters within three years.” Without subsidies, whaling would be economically unviable.

More whales in the fight against climate change

In addition to the carbon dioxide that whales capture in their bodies and store deep in the ocean when they die, they also fertilize the ocean with their feces and urine, leading to large phytoplankton blooms. Phytoplankton produce at least 50% of the oxygen in the atmosphere and capture an estimated 40% of all the carbon dioxide produced in the world, according to the IMF report. “To put things in perspective, we calculate that this is equivalent to the amount of CO2 captured by 1.70 trillion trees — four Amazon forests’ worth,” the report says.

Decades of industrialized whaling greatly reduced whale populations, a number of which have yet to fully rebound, and biologists estimate that there are now fewer than a quarter of the whales that once existed, according to whale experts Mongabay interviewed for this story.

“We are realizing that oceans were once more productive because there were so many whales,” said marine biologist Rodrigo Hucke-Gaete, a professor at the Austral University of Chile and president of the Chilean NGO Blue Whale Center, who was not involved in the recent study. “We need to let them recover to see if they are able, in their astonishing role that they play on a global level, to return the oceans to what they were at the time.”

A humpback whale mother and her baby near the water’s surface. Image by montereydiver via Flickr / CC BY 2.0.

The IMF magazine report calculates that if the 1.3 million or so whales alive today are left to rebound to their pre-whaling numbers of 4 million to 5 million, “it could significantly increase the amount of phytoplankton in the oceans.” Even if phytoplankton productivity increased by just 1%, it “would capture hundreds of millions of tons of additional CO2 a year, equivalent to the sudden appearance of two billion mature trees,” the report says.

The upshot, according to the report and whale experts consulted for this story, is that supporting international efforts to restore whale populations could help advance the fight against climate change.

For Hucke-Gaete and Cabrera, continuing to hunt whales makes no sense and does not align with the science. “We are in an enormous environmental crisis from which we do not know whether we will emerge,” Cabrera said.

“We should not have whaling in the 21st century,” Hucke-Gaete said. He noted, however, that other factors take an even greater toll on whale populations: collisions with ships; climate change, which is causing whales’ ecosystems and food supplies to shift and encouraging harmful algal blooms; pollution; and fisheries, which affect the entire marine food web as well as injure or kill whales that become entangled in fishing gear.

“We have to minimize every threat affecting whales (and marine ecosystems as a whole) arising from human activities through decisive and concerted actions,” Hucke-Gaete said. Because of their ability to capture and store atmospheric carbon, as well as the many other ways they help stabilize marine ecosystems, he said, “Every whale counts and we should take care of them as if they were the golden goose.”

 
Banner image courtesy of the Institute for the Conservation of Whales.

This article was first reported by Mongabay’s Latam team and published here on our Latam site on Nov. 11, 2020. Additional context was added in translating it to English.

Citation:

Mariani, G., Cheung, W. W., Lyet, A., Sala, E., Mayorga, J., Velez, L., … Mouillot, D. (2020). Let more big fish sink: Fisheries prevent blue carbon sequestration — half in unprofitable areas. Science Advances, 6(44), eabb4848. doi:10.1126/sciadv.abb4848

Pershing, A. J., Christensen, L. B., Record, N. R., Sherwood, G. D., & Stetson, P. B. (2010). The impact of whaling on the ocean carbon cycle: Why bigger was better. PLOS ONE, 5(8), e12444. doi:10.1371/journal.pone.0012444