Recent research has highlighted the previously overlooked role of sea kelp as a so-called "blue carbon" carbon capture process. These findings are especially significant in light of the Intergovernmental Panel on Climate Change (IPCC) 's recent publication, the latest Assessment Report (2021). Here, the importance of net-zero carbon emissions targets in avoiding the most devastating effects of human-induced climate change in the next century is evident.
IPCC's 2021 Assessment Report: The Need to Cut Carbon
The latest report from IPCC summarizes the scientific community's consensus: human-induced climate change is having a significantly detrimental impact on the planet and its ecosystems, and it will continue to do so. This article is part of an AZO Cleantech series that examines critical problems highlighted in the IPCC reports and possible technological solutions.
Assessment Reports are a regular publication by the IPCC, containing a sweeping review of the latest scientific literature on environmental sciences and climate change, and are underwritten by all United Nations (UN) member states' governments.
The IPCC report warns we must dramatically reduce the level of net carbon emissions to avoid the worst possible outcomes in the next few decades. Our reliance on burning fossil fuels for energy must be eliminated while natural carbon capture must be enhanced. If not, global warming is predicted to soar between 1.5 °C and 2 °C.
Can We Reach Net-Zero CO2 with Carbon Sequestration?
Carbon capture is a natural part of the carbon cycle and happens without human intervention. CO2 is captured or sequestered through biological, chemical, and physical processes in nature.
When trees and forests draw carbon out of the atmosphere through plant photosynthesis, that carbon is stored within the wood and soil in the forest ecosystem. This is natural carbon sequestration. However, human carbon emissions have strongly affected the natural carbon cycle since the Industrial Revolution. Natural methods can no longer keep pace with the amount of CO2 that is released by anthropogenic activities.
The consequences of these unsustainable atmospheric and oceanic carbon dioxide levels include global warming, rising sea levels, ocean acidification, and other adverse effects on the environment. Bolstering the natural carbon cycle's sequestration processes has been proposed as a potentially effective means of reducing the levels of CO2 in the atmosphere. It could also help to mitigate the subsequent detrimental impact this has on the entire planet's ecosystems.
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Artificial carbon capture projects include converting crop and grazing land into an area for fast-growing non-crop plants. In other methods, subsurface saline aquifers, reservoirs, and ocean water have been installed at the site of heavy CO2 emitters such as power plants, capturing carbon before it enters the atmosphere.
Despite these efforts, capture technologies have not been able to replicate the scale of carbon capture possible in natural systems such as forests and ocean algae. Advocates argue that more effort should be taken to preserve the systems that currently exist in nature.
The financial costs of artificial carbon sequestration, in particular, have impeded attempts to scale these technologies. If the costs of carbon capture using existing technologies were passed on to energy end-users, energy costs would increase by up to 5 cents per kilowatt-hour.
The energy costs of most carbon sequestration methods in use today also severely limit the overall environmental benefit of these projects. Char production, for example, requires vast amounts of energy to complete the necessary pyrolysis process. Although, these costs could be effectively mitigated by carbon sequestration projects using fully renewable energy sources.
Sea Kelp's Understudied Blue Carbon Potential
Oceans cover 70% of the planet's surface, and their ecosystems contain a significant amount of potential for carbon capture and sequestration. When this process occurs in oceanic and coastal ecosystems, it is referred to as blue carbon.
Blue carbon is contained in algae, seagrasses, macroalgae, salt marshes, and large ocean fauna like mangrove forests. Only recently has research explored its carbon sequestration potential, with early efforts focussing on the world's inland forests.
A study published on October 9th 2020 in the journal Nature Scientific Reports has highlighted the role of sea kelp as a potential for blue carbon capture. Historically, sea kelp has not featured in blue carbon research and forecasting. Researchers Karen Filbee-Dexter and Thomas Wenberg make a note of this, stating that while global carbon budgets and carbon offset schemes have recently taken the contributions of other kinds of blue carbon into account, sea kelp has been largely overlooked.
In their investigations, the kelp forests in Australia's Great Southern Reef were found to contain 10.3 to 22.7 Tg (teragrams) of carbon and sequester between 1.3 and 2.8 Tg each year; this is over 30% of blue carbon stored and sequestered around Australia and approximately 3% of the world's total blue carbon.
Can seaweed help curb global warming? | Tim Flannery
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Future Outlook for Sea Kelp
With the release of this research, sea kelp's carbon capture contribution in carbon assessments may be acknowledged, ensuring more accurate modeling and forecasting in the future. By highlighting the critical role of sea kelp, researchers also hope to draw attention to the issue of declining sea kelp forest health worldwide.
Due to extreme marine heatwaves, coastal pollution, general ocean warming, drought, and changing ocean fauna populations caused by climate change, sea kelp forests are deteriorating.
When kelp forests are degraded like this, around 89% of the blue carbon they contain is incorporated into food webs in the ocean ecosystem. Eventually, it reenters the atmosphere as mineralized CO2. Therefore, it is crucially important to monitor and preserve the health of sea kelp forests going forward.
Industrial Response to Climate Change
This article is a part of the IPCC Editorial Series: Industrial Response to Climate Change, a collection of content exploring how different sectors are responding to issues highlighted within the IPCC 2018 and 2021 reports. Here, Cleantech showcases the research institutions, industrial organizations, and innovative technologies driving adaptive solutions to mitigate climate change.
References and Further Reading
IPCC. (2018) Summary for Policymakers. Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. Available at: https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15_SPM_version_report_LR.pdf
IPCC. (2021) Summary for Policymakers. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate. Available at: https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf
Dexter-Filbee, K. and T. Wernberg. (2020) Substantial Blue Carbon In Overlooked Australian Kelp Forests. Scientific Reports. Available at: https://doi.org/10.1038/s41598-020-69258-7
Dwivedi, R. (2008) What is Carbon Sequestration? AZO Cleantech. [Online]. Available at: https://www.azocleantech.com/article.aspx?ArticleID=28
Gibbins, J. and H. Chalmers (2008) Carbon Capture and Storage. Energy Policy. Available at: https://doi.org/10.1016/j.enpol.2008.09.058
Ortega, A. et al. (2019) Important Contribution of Macroalgae to Oceanic Carbon Sequestration. Nature Geoscience. Available at: https://doi.org/10.1038/s41561-019-0421-8
Sedjo, R. and B. Sohngen (2012) Carbon Sequestration in Forests and Soils. Annual Review of Resource Economics. Available at: https://doi.org/10.1146/annurev-resource-083110-115941
UNEP. (2017) Blue Forests: Finding Coastal and Marine Solutions to Meet the Paris Agreement. UNEP. [Online]. Available at: https://www.unep.org/news-and-stories/story/blue-forests-finding-coastal-and-marine-solutions-meet-paris-agreement