Protecting Whales from Plastic: A Climate Action!

“If the ocean dies, we die”.

This cult phrase from Captain Paul Watson, famous defender of the whales, sums up the situation. Life appeared in the ocean 4.5 billion years ago, and the ocean has sustained it ever since. Unfortunately, today 5 major scourges threaten the Ocean: overfishing, climate change, habitat destruction, pollution and invasive species. Plastic pollution amplifies each of these threats.
Indeed, 40% of floating macro-waste comes from fishing. Plastic waste degrades habitats, from river banks to the seabed. Plastic waste is obviously a pollutant, and an ideal carrier for many invasive species.
But the link between plastic and climate is often overlooked, and yet plastic pollution is estimated to account for 10 to 13% of the world’s carbon budget.

99% of all plastics are made from petroleum. At every stage in the life of a plastic product, from the extraction of the material to the UV degradation of the waste itself in nature, plastics emit greenhouse gases.

Plastic not only emits CO2, it also inhibits the world’s largest carbon pump, the ocean. In fact, the ocean absorbs 30% of anthropogenic CO2 emissions through two mechanisms:

• The physical carbon pump. On contact with water, CO2 dissolves and acidifies the ocean, threatening calcareous species such as corals and shellfish.
• The biological carbon pump. Phytoplankton (all the plant species that drift with the currents) absorb CO2 through photosynthesis and transform it into organic matter. The carbon is then stored in living organisms and either passed on through the food chain, or sinks with the corpses and faeces of marine species to be stored on the seabed.

The starting point of the biological pump is phytoplankton. Like all plants, it needs sunlight, CO2 and water to photosynthesize. That’s why it’s found at the surface of the oceans. But it also needs nutrients to grow. Nutrients found in organic matter (remains of organisms, faeces, etc.) sink and never stay at the surface. So how can phytoplankton absorb the nutrients it needs to survive?

Whales can feed at great depths, but are obliged to rise to the surface to breathe. These vertical movements bring nutrients to the surface. But that’s not all! Because of the pressure at depth, whales can only poop at the surface, and the larger they are, the more extensive the “fecal feathers” they release, loaded with iron and nitrogen, representing a veritable fertilizer for phytoplankton!
What’s more, most whales migrate great distances, spreading this precious fertilizer all over the surface of the oceans!

Whales are the gardeners of the oceans.

More whales mean more phytoplankton, and therefore less CO2 in the atmosphere. But the power of the whale pump doesn’t stop there. Whales are huge – the largest, the blue whale, can measure up to 30 m in length and weigh 150 tonnes – and they represent a huge carbon sink. When they die in the ocean, all this carbon is transported to the abyss, where it is stored for millions of years. By dying and sinking to the bottom of the Ocean, a whale would trap around 33 tonnes of CO₂ per year, compared with 22 kilos for a tree. Finally, their corpses constitute veritable islands of biodiversity in which abyssal species feed, which without these whales would disappear for lack of food.

Thanks to this “Whale Pump” mechanism (Joe Roman, 2010), whales are changing the climate!

Every year, over 100,000 marine mammals die as a result of plastic pollution: entanglement, entanglement in fishing gear or ingestion of plastic waste (fishing tackle, plastic bags, bottles, etc.).

This figure, already too high, does not take into account the long-term consequences of microplastic ingestion. A study published in 2022 in Nature communications estimated that the blue whale could ingest 10 million particles of plastic less than 5 mm in size per day. Researcher Zhe Lu, professor of marine ecotoxicology at the University of Quebec, explains in a Reporterre article that “due to their lipophilic nature, microplastics have the potential to absorb persistent organic pollutants present in contaminated regions. Such as heavy metals, polychlorinated biphenyls (PCBs) and pesticides”. While research into the effects of microplastics is still in its infancy, we do know that macroplastic debris (> 5 mm) has been found in half the marine mammals sampled worldwide to date. A report by the United Nations Environment Programme makes this worrying observation, highlighting the fact that this pollution affects all marine ecosystems and reduces the efficiency of the biological pump, further accelerating climate change.

On February 19, we celebrated whales, but it’s every day that we should pay tribute to these oceanic gardeners.