Climate Change Puts Our Natural Carbon Sinks at Risk

Updated: Oct 22, 2021

By Hamilton Steimer


The Amazon is in trouble


If you paid attention to the news last week, you may have seen some concerning headlines involving the Amazon rainforest. Researchers announced in the scientific journal Nature that the Amazon rainforest was now a carbon emitter due to deforestation and climate change.


Historically known as “The Lungs of the Planet,” the Amazon rainforest, through the photosynthesis process, would absorb CO2 and produce oxygen. The Amazon was probably the most famous example of a carbon sink, a place that absorbs more carbon than it releases. However, over the last decade, the Amazon has been plagued by rampant deforestation as well as increasingly severe climate pressures.


From 2010 to 2018, researchers took almost 600 vertical profiles of CO2 and carbon monoxide concentrations in the lower atmosphere from four different sites in Amazonia. Meanwhile, the Amazon was being exploited for its natural resources and for agricultural purposes, which has been made worse under Brazil’s far-right president, Jair Bolsonaro. Forest fires, most set deliberately, released massive amounts of carbon dioxide into the atmosphere. The researchers concluded that over the last decade, the Amazon released 20% more CO2 than it absorbed, and they estimated the rainforest now emits about a billion metric tons of carbon dioxide annually.


The Amazon’s change in status from a carbon sink to a carbon emitter should trouble us all. The world relies on carbon sinks to help maintain the balance of the carbon cycle, but the planet’s natural carbon sinks are now at risk of becoming contributors to the climate crisis.


Carbon Sinks


The carbon cycle is the flow of carbon between the oceans, rocks, fossil fuels, plants, and even human beings and animals. About 45% of carbon is in the atmosphere with 25% in forests and 30% in the oceans. Ideally, carbon sinks and carbon emitters create a balanced carbon cycle, maintaining the Earth’s carbon concentration. However, human activity is releasing more carbon into the atmosphere than the planet and its carbon sinks can naturally handle. Now, like the Amazon, we are witnessing the degradation of the planet’s carbon sinks, and we must do everything possible to restore and strengthen them if we are to successfully combat climate change.


Forests


Forests typically act as large carbon sinks. Trees and other plants absorb carbon dioxide during the photosynthesis process, and the stored carbon is released once they die and decompose. Trees, in particular, can store massive amounts of carbon since they are 50% carbon by weight, and they can absorb 48 pounds of CO2 annually once they mature. Given that trees have very long lifespans, they can naturally absorb and store carbon for hundreds of years.


According to the World Resources Institute (WRI), between 2001 and 2019, forests absorbed twice what they emitted, absorbing a net 7.6 billion metric tonnes per year. However, the Amazon and other forests are under threat from human activity and climate change. Many forests are cut down and burned, so the land can be converted for agriculture and development. Other forests experience intense wildfires made worse by higher temperatures and drier conditions due to climate change. As forests burn, carbon that has accumulated within the trees over hundreds of years is released immediately. WRI estimates that only the Congo rainforest has enough standing rainforest to remain a strong net carbon sink.


Tundra


The Canadian Arctic and Russian Siberia are two prime examples of the tundra biome. The tundra is characterized by permafrost, any type of ground that has been frozen continuously for at least two years. The soils in the northern tundra are estimated to contain 1400-1600 billion metric tons of organic carbon consisting of the remnants of dead plants and animals that have built up over millennia.


Unfortunately, the carbon sink status of the tundra is climate-sensitive, and the Arctic is currently heating at twice the rate as the global average. As soils begin to heat up, microbes begin to decompose the organic matter and release greenhouse gases. At the current rate of warming, 40% of the world’s permafrost could disappear by the end of the century, resulting in a massive release of methane and CO2 into the atmosphere and a dramatic transformation of the tundra region.


Oceans


The world’s oceans absorb 22 million tons of CO2 per day, although the carbon is not evenly distributed as colder regions absorb the most CO2. Through atmospheric deposition, algae, and plankton, carbon is absorbed into the oceans with ocean circulation moving carbon down to the deep ocean water and floor sediments. Carbon concentrations are constantly in flux as oceans absorb CO2 when the concentration is higher in the atmosphere, but they release CO2 when the atmospheric concentration is lower. As the atmospheric concentration of CO2 has increased, the oceans have absorbed more CO2.


As carbon concentrations in the oceans continue to rise and water temperatures increase, oceans will be unable to absorb as much carbon as they have in the past. Besides the climate impacts, rising ocean carbon concentrations are leading to ocean acidification. When CO2 and H2O combine, they form carbonic acid, a weak acid. Since the industrial revolution, ocean acidity levels have increased by 30%. Increasing ocean acidity causes terrible marine life impacts, including dissolving the calcium carbonate shells and bodies of clams and corals.


How do we protect our carbon sinks?


Protect and Preserve Forests


We must protect and preserve existing forests, particularly old-growth forests, from overexploitation. Preserving forests is a guarantee the carbon within them stays out of the atmosphere, and with respect to American forests, President Biden’s “30 by 30” goal is a good start. However, there is currently a divide: those who see forests’ value as being sources of natural resources and those who see forests’ value as being sources of biodiversity and carbon storage resources. Unfortunately, convincing others to leave their natural resources alone is an uphill battle as the climate benefits of preservation seem too distant.


I think it is time we recognize the climate benefits of forests and natural lands and pay landowners accordingly. Countries concerned about climate change can either pay for the conservation efforts themselves, or they can pay landowners for the carbon reduction potential of their lands using the social cost of carbon. Countries that want to expand their economies and continue their economic development will only protect their natural resources if they do not have a financial incentive to develop them. By paying for forest conservation efforts or by directly rewarding forests’ carbon storage services, we can ensure countries like Brazil protect and preserve their forests and natural resources.


Get Off of Fossil Fuels


Changing climate conditions are pushing forests, oceans, and the tundra to the brink, and they are at risk of becoming carbon emitters instead of carbon sinks. Some of these carbon sinks, such as the Amazon, are already becoming carbon emitters, and as global temperatures continue to rise, they will release more and more carbon into the atmosphere. Therefore, anything that can mitigate the advance of climate change will benefit our carbon sinks.


The most obvious solution is to stop the use of fossil fuels for energy. President Biden’s climate agenda is a good first step for the United States toward reducing its greenhouse gas emissions, although his agenda’s future is at risk. While the US has made decent progress, at least in the electricity sector, rapid decarbonization remains a challenging task. A Bright Future by Joshua Goldstein and Staffan Qvist explores this dilemma and explains why they fully endorse nuclear energy.


Achieve Negative Emissions


Ending the use of fossil fuels will not be enough to prevent the worst impacts of climate change. Carbon dioxide and other greenhouse gases will remain in the atmosphere for years, still contributing to rising global temperatures long after we have stopped using fossil fuels. If we want to halt the advance of climate change and save our carbon sinks, we need to achieve negative emissions, where we withdraw enough emissions to ultimately reduce the concentration of greenhouse gases in the atmosphere.


You may have heard of the One Trillion Trees Initiative or the Trillion Trees Act, two climate solutions based on the dubious results of a study that suggests we could solve the climate crisis by planting a trillion trees. This silver bullet solution has gained traction in recent years, but it has also received a lot of criticism for oversimplification and exaggerated calculations. While planting more trees via reforestation and afforestation is a great idea, the trillion trees solution may not be the most reliable solution.


Another negative emissions solution is carbon sequestration, the process of capturing and storing atmospheric carbon dioxide in solid or liquid form. There are three types of carbon sequestration: biological, geological, and technological. Forests, algae, and plankton perform biological sequestration through the photosynthesis cycle. Geological sequestration is when carbon dioxide is captured and injected underground into porous rocks for long-term storage. The most well-developed technological sequestration solution is direct air capture, a process where the air is moved over chemicals that selectively react with and remove CO2.


Direct air capture, while exciting, is very expensive and costs between $250-600 per metric ton of CO2 captured. For now, this solution is too expensive to be financially acceptable, but hopefully, we can reduce the costs with continued research and development.


Reversing climate change is getting harder


Climate change and our degrading carbon sinks reveal the power of positive feedback loops. Because of climate change, our carbon sinks become carbon emitters, and their emissions accelerate climate change even more. Our carbon sinks may soon become part of the climate problem if we don’t take aggressive steps to protect them, rapidly decarbonize, and achieve negative emissions.


We are quickly learning that the Earth has been in a delicate natural balance, but human activity is beginning to disrupt that balance with catastrophic effects. Now we find ourselves on a slippery slope. Solving this crisis is more difficult now than if we tried to solve it 10, 20, 30 years ago. If you thought things were bad already, imagine how much worse things will be if we don’t take decisive action! Contact your representatives, change your consumption habits, put pressure on corporations, do something to make your voice heard! The planet is counting on you.


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