Heat waves, droughts and extreme weather events endanger people and ecosystems in some part of the world almost every day. These extremes are exacerbated by climate change, largely caused by increased emissions of greenhouse gases that accumulate in the atmosphere and trap heat on the Earth’s surface.
With that in mind, researchers are looking for ways to draw carbon dioxide out of the atmosphere and trap it. This includes ocean use. However, while these techniques may work, they raise serious technical, social, and ethical questions, many of which still do not have clear answers.
We research climate change policy, sustainability and environmental justice. Before people start experimenting with ocean health, there are some important questions to consider.
Marine Carbon Dioxide Removal 101
Oceans cover about 70% of the Earth’s surface and absorb carbon dioxide naturally. In fact, about a quarter of anthropogenically produced carbon dioxide ends up in the ocean.
Marine carbon dioxide removal is an activity aimed at using the oceans to remove more carbon dioxide than it already removes and stores from the atmosphere.
From increasing the abundance and vigor of carbon dioxide-absorbing mangrove forests, to using ocean fertilization to stimulate the growth of carbon dioxide-absorbing phytoplankton, to building pipelines that pump liquid carbon dioxide into the subseafloor. It spans a wide range of technologies, from building to building. It eventually solidifies as carbonate rock.
There are other ways to remove carbon dioxide. For example, planting trees. However, it requires large amounts of land for other important uses such as agriculture.
Therefore, there is a growing interest in utilizing the vast ocean.
Can we store enough carbon with these methods?
The first key question is whether ocean carbon dioxide removal technologies can significantly reduce atmospheric carbon dioxide and preserve it over the long term beyond what the ocean already does. Greenhouse gas emissions are still increasing globally. This means that we need to remove ocean carbon dioxide to keep it out of the atmosphere, at least until greenhouse gas emissions decrease.
Early evidence suggests that some forms of ocean carbon dioxide removal, such as those that rely on short-lived biomass such as kelp forests and phytoplankton, may not preserve captured carbon for decades. This is because most plant tissues are rapidly recycled through decay and prey by sea life.
In contrast, mechanisms that form minerals, such as interactions when carbon dioxide is pumped into basalt layers, or mechanisms that alter the way seawater retains carbon dioxide, such as increasing its alkalinity, prevent carbon from escaping. Much more likely to prevent and maintain it.Atmosphere unchanged for hundreds and thousands of years.
Ecological risks and benefits
Another important question is what are the ecological benefits or risks associated with different marine carbon dioxide removal approaches.
Studies show that some options, such as supporting mangrove forests, can promote biodiversity and benefit nearby human communities.
Other options, however, may introduce new risks. For example, growing large amounts of kelp or algae and then submerging them can introduce invasive species. This increases the ocean’s ability to store carbon dioxide, but these rocks may also contain trace amounts of metals that can harm marine life, and these risks are Not well understood.
Also, each process can emit greenhouse gases, reducing overall effectiveness.
Interference with nature is a social problem
The ocean affects everyone on the planet, but not everyone has the same relationship with it or the same opportunities to be heard.
A large portion of the world’s population lives near the ocean, and some interventions could affect where jobs and communities are supported. For example, promoting algal growth can affect nearby wild fisheries or interfere with recreation. You’re trying to assess risk differently.
Additionally, people’s trust in decision-makers often shapes how people view technology. The use of oceans to remove carbon dioxide, such as those close to shore, may be managed on a regional basis. It is less clear how decisions about high seas and deep waters are made. This is because these waters are not under the jurisdiction of any particular country or global governing body.
People’s perceptions can also be shaped by factors such as whether they see the removal of marine carbon dioxide as hindering or protecting nature. However, your view of what is acceptable and what is not may change. As the impacts of climate change grow, there seems to be a growing tolerance for some unconventional interventions.
It’s also an ethical issue
Removal of marine carbon dioxide also raises various ethical questions for which there are no easy answers.
For example, it makes me think about relationships between humans and non-humans. Do humans have a duty to intervene to reduce their impact on the climate, or should they avoid intervening in the oceans? Do people have the right to intentionally intervene in the oceans? When considering such options Are there specific obligations that humans should be aware of?
Other ethical issues relate to who makes decisions about marine carbon dioxide removal and its consequences. For example, who should be involved in decision-making about the oceans? Relying on marine carbon dioxide removal is a way to reduce emissions through other means, such as reducing consumption, increasing efficiency, and transforming the energy system. Can social commitment be reduced?
Finally, marine carbon dioxide removal can be very costly.
For example, it is estimated that mining and adding rocks to reduce ocean acidity costs between $60 and $200 per tonne of carbon dioxide removed. Given this, in 2021 the world will generate more than 36 billion tons of carbon dioxide from energy alone.
Even the cultivation of macroalgae could be worth tens of billions of dollars if done on the scale deemed necessary to make an impact.
These methods are more costly than many actions that currently reduce emissions. Avoiding carbon emissions by using solar panels, for example, ranges from money savings to costs of $50 per tonne of carbon dioxide, while actions like reducing methane emissions cost even less. However, continued climate change is estimated to cost hundreds of billions of dollars annually in the United States alone.
These costs raise even more questions. For example, how much debt is appropriate for future generations to bear, and how should costs be distributed globally to solve global problems?
Marine carbon dioxide removal could be a useful way to curb global warming, but should not be viewed as a silver bullet, especially since there is no effective global system for making decisions about the oceans.
New study may reveal how carbon dioxide emissions from the Southern Ocean affect climate change
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