BC’s carbon sinks: the natural and human-created solutions to climate change

Human activities that burn fossil fuels such as coal, oil, and gas have released huge amounts of carbon into the atmosphere. Atmospheric carbon dioxide has increased by more than 40% since the Industrial Revolution, leading to a rise in global temperatures and resulting in climate change.

Carbon is removed from Earth’s atmosphere by carbon sinks. A carbon sink can be natural or human-created. 

Landscapes are the biggest natural carbon sinks. “Forests are carbon sinks, and wetlands and bogs,” says Naoko Ellis, Associate Director, Clean Energy Research Centre at the University of British Columbia. “Those are areas that we actually have a lot of in the Lower Mainland.” 

Many people around the world are working on technology to artificially capture carbon. “Once you capture it, you have to do something with it,” says Ellis. In BC, we are mapping possible locations to artificially store captured carbon underground. 

Let's take a look at BC's natural and human-made carbon sinks:

Forests 

Trees are famous for their ability to store carbon in wood, leaves, and soil. In the past, BC’s large forests stored more carbon than they created. But the increasing number of trees killed by insects or burned in fires means that many of our forests are now creating more carbon than they store. 

BC's government has recently announced new measures to protect more old-growth forests by co-developing local plans with local First Nations. With the participation of 50 First Nations, Forest Landscape Planning incorporates local knowledge and community priorities. It prevents harvesting in old-growth forests that are important for ecosystem health, biodiversity, clean water, carbon storage and Indigenous values. 

Oceans, Estuaries, and Marshes 

Oceans, estuaries, and salt marshes are a major carbon sink. Atmospheric carbon dissolves into the ocean, where it can stay dissolved or be absorbed by sea creatures or plants. 

When carbon stays dissolved in water, it makes water more acidic. In the open ocean, this water will sink, staying trapped for decades or centuries until returning to the surface. Some of the carbon will also be used by plankton, sinking to the sea floor when they (and the creatures that eat them!) die. In some places like off the coast of BC, this sea floor is very slowly transported into the Earth’s interior by plate tectonic movement. While this can store carbon for millions of years, it also happens very slowly compared to other carbon sinks. 

In shallow water near coastlines, plants like seagrass trap carbon the same way trees on land trap carbon. When those plants die, the carbon is buried in soil and stays trapped for hundreds to thousands of years. British Columbia has a very jagged coastline with lots of rivers, so we have many estuaries for seagrass to grow and trap carbon. Eelgrass is particularly good at trapping carbon.  

When you’re at the coastline at low tide, be careful of exposed seagrass and do your best to not damage these important but fragile ecosystems. 

Soils

Carbon can also be stored in soil. Plants naturally absorb carbon from the atmosphere. Some of this carbon is used to grow plant stems, leaves, and flowers. But some of this carbon is released by plant roots as a sugary substance into the soil. Even more carbon is released into the soil when plants and animals die and are buried. That carbon is eaten by soil microbes. If the microbes are undisturbed, they can trap carbon in the soil for thousands of years. 

Right now, farming and raising animals produce a lot of carbon in British Columbia. This might change with more research into better farming techniques and adoption of better farming practices. In the Prairies, more carbon is stored in soil than is produced by farming. This is because of how farmers prepare the land for planting, how they use fertilizers, what crops they plant, and how they treat the forest after harvest. Scientists hope that by protecting soil microbes, agriculture can help soil trap more carbon while also allowing crops to grow better. 

Artificial carbon storage 

Engineers and scientists are working on new technology to artificially trap carbon. Some of these ideas focus on capturing carbon as it is emitted from sources like factories and cars. Other ideas focus on absorbing carbon from the atmosphere. BC has recently started to investigate the storing of captured carbon deep underground. This process is called geologic carbon sequestration.  

“The most popular thing to do is to inject it underground, where depending on the rock formation, it starts to form carbonates.” says Ellis. “It starts to become a part of a rock underground, which is a slow process.”  

If carbon is injected underground in the right sort of rock formation, it can be trapped and stay underground. Carbon can be injected into porous rocks like sandstone that have holes. This allows liquids and gasses like water, oil, gas, and liquid carbon to travel through the rock. However, these porous rocks need to have a solid rock like granite on top of them to keep the gas from rising back to the surface. If the carbon is successfully trapped underground for very long times, it will react with the surrounding ground to create new carbon-rich rocks like limestone. The best places to store carbon are oil and gas reservoirs, salt caverns, salty underground aquifers, and the same places where we find coal. 

Carbon capture and sequestration technologies are promising, but they are also very expensive. The best technique to slow climate change is to reduce how much carbon we produce. 

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