Can blue whales really capture carbon?

The concept of carbon capture, which involves removing carbon from the atmosphere and either changing its form or concentrating and storing it away so it does not reenter the atmosphere, is controversial. 

Carbon capture and storage is a technology that has been around for a long time, having been commercialised back in the 1970s. In the past, it was referred to as enhanced oil recovery, as the carbon dioxide obtained from oil and gas production was injected into depleted oil and gas reservoirs to help re-pressurise them and extract more hydrocarbons.

As the climate change movement gained momentum, the oil and gas industry rebranded enhanced oil recovery into a "climate-friendly" process known as carbon capture utilisation and storage (CCUS), according to Bruce Robertson, an Energy Finance Analyst at the Institute for Energy Economics and Financial Analysis.

However, more than 70 per cent of CCUS projects are used to produce more oil and gas through enhanced oil recovery, leading to more greenhouse gas emissions.

The Institute for Energy Economics and Financial Analysis notes most of the carbon captured throughout history has been used in enhanced oil recovery. This accounts for approximately 80-90 per cent of existing carbon capture projects. Only a tiny proportion of these projects (around 10-20 per cent) have stored carbon in dedicated geological structures without utilising it for oil and gas production.

Whale poo for carbon removal

The concept of carbon capture and storage, though not yet widely available outside the oil and gas industry, is gaining traction and showing promise. A collaborative effort between several prestigious institutions, including Cambridge University, the Woods Hole Oceanographic Institution in Massachusetts and the Institute of Maritime Studies in Goa, is focused on scaling greenhouse gas removal efforts and replenishing ocean ecosystems with marine life.

Whales play a fascinating role in this process. They cannot defecate underwater due to the pressure that seals their orifices, making their waste deposition a surface phenomenon.

When these majestic creatures surface, they release carbon-rich waste into the ocean. Their iron-rich faeces greatly encourage phytoplankton and marine plants to grow, which go on to remove carbon from the atmosphere through photosynthesis in a biosystem equivalent to a land-based forest. 

Humans have been exploiting whales for a long time. The discovery of oil originally stemmed from whale blubber, and humanity's longstanding exploitative relationship with these marine giants has disrupted crucial ecological cycles.

Innovative solutions are now being explored, including the possibility of introducing artificial whale poo to the surface of the ocean. According to renowned climate scientist Sir David King, the project lead, this approach could sequester between 3 and 12 billion tonnes of carbon, significantly contributing to global carbon mitigation efforts. That amount of carbon sequestration is equivalent to up to 1.5 billion homes' energy use each year (there are an estimated 2.3 billion homes worldwide).

Carbon is found in all living things, so plants and animals act as carbon reservoirs throughout their lifetimes.

Whales as carbon sinks

Whales also sequester carbon when they are alive. Animals that are larger and live longer store more carbon, which is why marine megafauna, such as whales, play a vital role in reducing global carbon emissions.

Whales live on a diet of carbon, not fish. A whale that survives to be 60 will accumulate 33 tonnes of CO2 on average. 

When they die, whales sink to the seafloor, trapping the vast quantities of carbon in the seabed, unlikely to resurface for thousands of years.

Industrial whaling decimated whales in the twentieth century. Still, before that, their populations (excluding sperm whales) were bringing up to 1.9 million tonnes of carbon per year to the ocean bottom - the equivalent of taking 410,000 cars off the road each year.

Restoring whale populations is, therefore, one of many remarkable solutions the ocean offers to help tackle the climate crisis.

Whale conservation is a climate policy

Whales play a critical role in mitigating climate change. A single fish lays hundreds of thousands of eggs yearly, but without phytoplankton, these eggs perish. Phytoplankton, in turn, relies on nutrients found in whale excrement to flourish, forming vital ecosystems at the ocean's surface. This interconnected web demonstrates the importance of preserving whale populations, not just for carbon sequestration but also for maintaining biodiversity.

Efforts to conserve whale populations are essential for maximising their carbon capture potential. Threats such as commercial whaling, habitat degradation, and marine pollution jeopardise whale populations worldwide. 

International regulations, such as the International Whaling Commission's moratorium on commercial whaling and various marine protected area designations, are crucial to safeguard whale populations and their habitats. These regulations aim to mitigate human-induced harm and ensure the long-term survival of whales and the ecosystems they support.

Recognising whales' significant carbon sequestration potential presents an opportunity to integrate whale conservation into broader climate policies. 

Acknowledging these ecosystem services whales provide can incentivise policymakers to develop innovative strategies to combat climate change effectively. This may involve strengthening existing regulations, such as enhancing enforcement mechanisms for marine protected areas and implementing stricter measures to reduce maritime pollution. 

A recent and promising development took place in the UK: MPs announced that the UK government has failed whales, dolphins and other marine mammals and called for ministers not to sign trade deals without considering cetacean welfare. Perhaps governments are beginning to realise the ocean's decarbonisation potential.  

Image by Thomas Lipke.