The role of wild animals in carbon sequestration

It is no secret that we are facing a climate crisis. The planet has been on a dangerous trajectory for several years, and now the consequences have caught up to us. There is widespread agreement in the scientific community that the temperature of the globe has risen at an alarming rate in recent years and that this rise is primarily due to human activity.

Specifically, the rise in global temperatures can be attributed in large part to the release of greenhouse gases—compounds that act like the glass in a greenhouse, trapping heat and warming the atmosphere.

The most common of these greenhouse gases is carbon dioxide (CO2). While governments around the world have put plans in place to reduce the level of carbon emissions and move toward net-zero futures, many of these efforts are focused on industrial and other human-driven activities.
Although these types of activities are many of the main drivers of climate change, it is easy to overlook the role the natural world plays in regulating global temperatures. In this blog, we explore the topic of carbon sequestration and how wild animals contribute to this critical function of the planet. 

The role of carbon dioxide

Before we dive into exactly what carbon sequestration is, let’s first examine the role of carbon—and by extension CO2—in the regulation of global temperatures.

Regulating temperatures on land

CO2 is the most abundant and important greenhouse gas in the atmosphere. In the face of scientific consensus that CO2 and other greenhouse gases are responsible for climate change, it may be tempting to think that we need to remove all of the CO2 from the atmosphere. However, this couldn’t be further from the truth.

Greenhouse gases—CO2 included—play a vital role in keeping the Earth at a temperature suitable for life. With proper atmospheric levels of CO2, heat radiating from the earth’s surface is trapped and released in multiple directions, including back down towards the surface. This mechanism is crucial for keeping global temperatures above freezing and sustaining life.

This is a finely tuned system that has been operating without issue for millions of years, leading to the development of the planet we live on today. The problem arises when humans release vast quantities of CO2 into the atmosphere, primarily by burning fossil fuels, amplifying the greenhouse effect and causing dangerous rises in temperatures.

Balancing pH at sea

As with all aspects of the environment, the ocean is a tightly controlled system that only functions optimally within a certain temperature and pH range. Atmospheric CO2 plays an important role in keeping the ocean’s balance by dissolving in the water and lowering its pH. 

However, the greenhouse effect causes ocean acidification—a process that involves surplus CO2 dissolving in the water, leading to a drop in pH and causing an imbalance in the ocean’s ecosystem. 

What is carbon sequestration?  

Carbon sequestration refers to the process by which atmospheric carbon is captured and stored. This removes CO2 from the atmosphere and helps mitigate the greenhouse effect.

There are two main ways in which carbon sequestration can occur—biological carbon sequestration and geological carbon sequestration.

Biological sequestration

Biological sequestration refers to CO2 that is captured and stored by animals, plants, and the soil. Much of this sequestration occurs in carbon sinks—natural features that absorb large amounts of CO2 such as forests, the ocean, and swamps (wetlands and peatlands). This is known as an indirect or passive form of sequestration, as it occurs naturally without human input. 

However, preserving this form of carbon sequestration relies on humans to protect and safeguard the natural world. With so much environmental destruction and disruption, we risk losing more of these carbon sink areas and exacerbating the greenhouse effect by indirectly raising levels of CO2 in the atmosphere.

Geological sequestration

Geological sequestration refers to CO2 that is captured and stored by geological formations and rocks. This is a direct form of sequestration as it is largely artificial, possible only with human input. Geological sequestration can be used to offset and mitigate CO2 emissions from human activities. 

With new technologies, large amounts of CO2 can potentially be stored in geological formations, removing it from the atmosphere and helping to blunt the greenhouse effect.

How wild animals contribute to carbon sequestration

When we think of biological carbon sequestration, it is tempting to think only about plants, as they take in CO2 and release oxygen. However, it is not just plants that play a role in biological carbon sequestration.

Animals also play a crucial role in the capture and storage of carbon from the atmosphere. Experts have found that strong, healthy populations of just nine different types of animals, including sea otters, grey wolves, and whales, could lead to the capture of 6.41 gigatons of CO2 every year. This represents 95% of the CO2 that needs to be removed from the atmosphere to ensure global warming remains below 1.5°C.

There are many ways in which animals contribute to carbon sequestration:

• Their natural behaviours increase ecosystems’ carbon storage capacity. Many animals perform carbon-sequestering roles as a part of their day-to-day lives. In particular, large vertebrates can increase an ecosystem’s carbon storage capacity by up to 250% through behaviours such as trampling, burrowing, and foraging.
• They support the growth of carbon-sequestering trees and plants. Many herbivore species disperse seeds in their faeces after eating plants, facilitating the growth of carbon-sequestering trees and plants. Others, like elephants, trample or eat the vegetation that would otherwise rob those trees of space and nutrients. This frees up room for carbon-sequestering vegetation to grow and means they do not have to compete with other foliage.
• They keep the ecosystem in balance. The ecosystems of the world are all finely balanced and keep themselves in check. Predators prey on herbivores that, without predation, might adversely impact essential fauna. This, in turn, ensures that carbon-sequestering plants can thrive at the correct levels in the environment.

Examples of animals that support carbon sequestration

We’ve looked at how wild animals can support carbon sequestration in their environments—now let’s explore some specific examples of animals that help remove carbon from the atmosphere.

African forest elephants

African forest elephants are smaller than their savannah elephant cousins and, as their name suggests, are found in the tropical forests of sub-Saharan Africa. It is estimated that they spend roughly 20 hours a day foraging for food.

It is in this foraging action that they assist with carbon sequestration. They prune the forests around them in their search for food, freeing up space and nutrients for the growth of larger, more mature trees that sequester more carbon than the low-level foliage they consume. In this way, African forest elephants sequester over 9,000 tonnes of carbon in their lifetimes.

Whales

We’ve already discussed the importance of the ocean as a carbon sink, and whales play a key role in this sequestration. Whales feed phytoplankton—tiny, plant-like organisms that float in the water—with their faeces and help them thrive. Through photosynthesis, these phytoplankton capture roughly 37 billion tonnes of CO2 per year, equivalent to 40% of the total CO2 capture on the planet.

Wolves

Wolves and humans have had a rocky relationship over the years. Although early humans domesticated these animals and many of us now share our homes with their descendants, wolves have also been wiped out from many areas.

This has led to the unbalancing of various ecosystems—in places like Yellowstone National Park—allowing populations of prey animals to explode and devastate plant life in the area. Additionally, wolves are often killed using toxic poisons, which also damage the environment and kill other animals and plants, exacerbating the problem.

By reintroducing wolves into their former habitats, they can help bring ecosystems back into balance through predation and allow carbon-sequestering plants to thrive once again.