What is the Potential for Sequestering Atmospheric Carbon in Natural Systems?

 

Summary

 

The short answer is that it is so immense that it can not only remove all the CO2 generated worldwide each year but can significantly reduce CO2 below current levels. There is a growing body of solid scientific research validating just how much CO2 is being removed and sequestered long term in soils and natural systems through existing management approaches already in use around the world.

 

CO2 molecule

CO2 molecule

Our conclusion is that at the very least there can be no doubt based on this evidence that the win/win approach to sequestering atmospheric carbon in natural systems could buy the globe at least 75 to 100 years of declining CO2 levels. That would be more than enough time to transition to a sustainable future in the most economical, sensible and responsible way.

 

Unlike any alternative to dealing with CO2 these approaches are immediately scalable and are not only cheaper than any other approach being considered but generate a number of environmental and economic co-benefits at the same time.

 

In considering what the potential is for sequestering atmospheric carbon it is essential to understand that this concept has already been endorsed by scientists around the world and the international community.  The Paris Accords (see our analysis here) recognizes the importance of natural sinks as a means of reducing atmospheric CO2 and encourages protecting and expanding them.

 

Sequestration in natural systems has also been adopted as an interim approach to dealing with rising CO2  levels by nearly 40 developed and developing countries (but not the United States) through a voluntary international agreement called “4 per Thousand.” Spearheaded by France, these countries along with nearly 200 non-governmental organizations (NGOs) financial institutions, regional development agencies and university research institutes have all agreed to develop and implement policies to increase the average soil carbon stocks in just the worlds agricultural and forest soils by an average of just 0.4% per year. Research shows that if that can be accomplished all of the projected increase in anthropogenic CO2 emissions over the next several decades could be safely sequestered. As we explain in our analysis of 4 per Thousand, this is a very conservative goal and the potential is much greater.

 

The articles highlighted below represent just a small portion of this growing body of research. We have selected them to give an overview of the kind of research being done and the results that are being achieved.

 

(Also see our Policy and Analysis Brief, “Measuring the Amount of Carbon Captured in Natural Systems”.)

(Note that some of this research refers to tons of carbon sequestered and some refer to tons of CO2. It is essential to keep in mind which is being reported. The carbon atom represents about 27% by weight of the CO2 molecule so to convert the amount of carbon being sequestered into the weight of the CO2 removed from the atmosphere, multiply the amount of carbon by 100/27 or 3.7. For example, every ton of carbon sequestered represents 3.7 tons of CO2 removed from the atmosphere. Also, most of these scientific reports use the metric area measurement “hectare” (abbreviated “he”) which is equivalent to approximately 2.5 acres, so it is important to also keep in mind the area measurement system being used. In most cases, we have done these conversions for you in our summaries.)

“Drawing Down Carbon at the Landscape Level”

 

“Drawing Down Carbon at the Landscape Level” is a video presentation by New Mexico State University professor Dr. David Johnson in which he explains the truly astonishing carbon sequestration results he has obtained using his “Biologically Enhanced Agricultural Management System” (BEAM) on croplands. He has averaged a 0.24% increase in soil carbon in just the top foot of soil, which means approximately 15 tons of CO2 /ac/yr is being drawn from the atmosphere. At that rate he calculates that it would take only 40% of the world’s arable land to capture all anthropogenic (“human caused”) CO2 emissions. Using what he calls “Advanced BEAM” he projects being able to increase soil carbon levels by 0.51%/yr in the top one foot and thereby draw down approximately 28 tons of CO2 /ac/yr. At that rate, he calculates that it would require only 25% of the arable land worldwide to capture all anthropogenic CO2. His approach also generates a wide range of co-benefits, such as greatly increased yields, reduced production costs and more efficient water utilization. Also, keep in mind that other natural sinks for CO2, such as forests and rangelands have huge potential for capturing CO2 as well. The discussion of carbon sequestration begins at approximately 13:45 on this video. View it here.

“Carbon that Counts”

 

“Carbon that Counts” by Dr. Christine Jones, a world-famous pioneer in sequestering carbon through agricultural practices, is a report and commentary on the amount of carbon sequestered on Winona, a farm in Australia and one of the first demonstrations in the world to be extensively studied. The study period extended from 2000 to 2010, which also happened to be a period of below average rainfall, making the results even more impressive. The amount of carbon sequestered actually increased over the 10 year study period, especially after livestock grazing was introduced as part of the management approach. In the last two years of the study period, approximately 13 tons of CO2 was being sequestered per acre per year. During the study period, the carbon was being sequestered at increasingly deeper levels in the soil and nearly 80% of the carbon was being sequestered in a highly stable form. Mineral availability also increased dramatically over the study period. Read it here. 

“Regenerative Organic Agriculture and Climate Change: A Down-to-Earth Solution to Global Warming”

 

“Regenerative Organic Agriculture and Climate Change: A Down-to-Earth Solution to Global Warming” is a report by the world-renowned Rodale Institute that looks at the carbon sequestration rates achieved in field trials around the world and projects how much CO2 could be sequestered if these were implemented worldwide. They conclude “At Rodale Institute, we have proven that organic agriculture and, specifically, regenerative organic agriculture can sequester carbon from the atmosphere and reverse climate change… With the use of cover crops, compost, crop rotation and reduced tillage, we can actually sequester more carbon than is currently emitted, tipping the needle past 100% to reverse climate change.” The report explains the various techniques that have successfully sequestered massive amounts of CO2 and show that not only can regenerative organic agriculture be more productive than conventional agriculture, it is much more profitable and uses far less energy inputs. Read the report here. 

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“Restoring Atmospheric Carbon Dioxide to Pre-Industrial Levels: Re-Establishing the Evolutionary Grassland-Grazer Relationship”

 

“Restoring Atmospheric Carbon Dioxide to Pre-Industrial Levels: Re-Establishing the Evolutionary Grassland-Grazer Relationship” Provenza, et al. From the abstract: “We maintain that it has the potential to remove excess atmospheric carbon resulting from anthropogenic soil loss over the past 10,000 years and as well as all industrial-era greenhouse gas emissions. This sequestration potential, when applied to up to 5 billion hectares of degraded range and agricultural soils (former wild grasslands), could, in theory, return 10 or more gigatons of excess atmospheric carbon to the terrestrial sink annually and lower greenhouse gas concentrations to pre-industrial levels in a matter of decades.” Read it here.

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“Emerging land use practices rapidly increase soil organic matter”

 

“Emerging land use practices rapidly increase soil organic matter,” is an article by Machmuller, et al, in Nature Communications. They found that “In a region of extensive soil degradation in the southeastern United States, we evaluated soil C accumulation for 3 years across a 7-year chronosequence of three farms converted to management-intensive grazing. Here we show that these farms accumulated C at 8.0 Mg ha−1 yr−1, [ equivalent to approximately 11.7 tons of CO2/ac/yr ] increasing cation exchange and water holding capacity by 95% and 34%, respectively. Thus, within a decade of management-intensive grazing practices soil C levels returned to those of native forest soils, and likely decreased fertilizer and irrigation demands. Emerging land uses, such as management-intensive grazing, may offer a rare win-win strategy combining profitable food production with rapid improvement of soil quality and short-term climate mitigation through soil C-accumulation.” Read the study here. 

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“Carbon Sequestration in Semi-arid Ecosystems: Potential Benefits of Sagebrush Restoration”

 

“Carbon Sequestration in Semi-arid Ecosystems: Potential Benefits of Sagebrush Restoration” is a paper presented by Austreng, et al. at the Fall, 2011 meeting of the American Geophysical Union. From the Abstract: “The results of our work indicate that sagebrush restoration may have the potential to offset 23% of annual US carbon emissions. Invasion of native sagebrush communities by cheatgrass in semi-arid ecosystems of the Intermountain Northwest is degrading ecosystem structure and function and can significantly decrease soil carbon contents… The results of our work indicate that this stepwise reclamation strategy [to restore ecosystem structure and function] will produce significant increases in soil carbon storage with conversion of cheatgrass to bunchgrass facilitating carbon storage benefits of ~15 t C per hectare [approximately 22 tons of CO2/ac]and a bunchgrass to native sagebrush benefit of ~17 t C per hectare [approximately 25 tons of CO2/ac]. Extending these results to all ~10 million ha of cheatgrass-infested ecosystems in the Great Basin, suggests that sagebrush restoration may have the potential to compensate for 23% of US annual carbon emissions.” (Note: There are more than 100 million acres of sagebrush steppe in the U.S., much of it similarly degraded, and an additional more than 40 million acres of sagebrush shrubland, so there is huge potential for carbon sequestration just across these ecosystems.  Based on this research, the entire U.S. carbon footprint could be sequestered annually in just the sagebrush lands of the U.S.) Read the abstract here. 

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“GHG Mitigation Potential of Different Grazing Strategies in the United States Southern Great Plains”

 

“GHG Mitigation Potential of Different Grazing Strategies in the United States Southern Great Plains,” an article by Tong Wang, et al. published in the journal “Sustainability” looks at the question of net GHG (greenhouse gas) emissions from cattle grazing. It tested the impact of three different grazing approaches on unfertilized rangelands in this region of the U.S., which is characterized by relatively low-quality forage content, a condition that increases relative methane emissions from cattle. Methane is considered to have about 25 times the global warming impact of CO2. Compared to conventional grazing practices, using multi-paddock (MP) rotational grazing not only improves forage quality and quantity but it sequesters enough CO2 to compensate for the warming impact of the methane emitted by the cattle and sequester an additional approximately 800 lbs per acre as well, making it a net sink. From the abstract: “our analysis indicated cow-calf farms converting from continuous to MP grazing in SGP [Southern Great Plains] region are likely net carbon sinks for decades.” (Note that in making these calculations the authors did not take into consideration the consumption of the methane produced by the cattle by the methanotropic (methane eating) bacteria present in the soil. Since some researchers have concluded that these bacteria consume most or all of the methane produced by cattle on rangelands, the actual sequestration rates of CO2 by the MP grazing approach are much higher.) Read it here.

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There are no big, well funded and well-organized groups pushing for this approach because they do not stand to make the huge profits they will with the mechanical alternatives to dealing with CO2 that they are pushing. So, if this win/win approach is to become the first policy choice for dealing with excess CO2 it is up to people like you to help make it happen. You can easily and securely donate to support our efforts here.

 

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