Do Plants Prevent Atmospheric CO2 Levels from Falling Too Far?

by Emil Morhardt

A recent paper discussed in the previous post (Galbraith and Eggleston, 2017) claims that during the past 800,000 years when the Earth has been in a glacial condition with the occasional interglacial period (such as now), there is a strong correlation between global temperature and atmospheric CO2 levels, and that they tend to go to the same low point again and again and stay there. These authors argue that if CO2 were to go lower, so would the temperature, and that therefore something is keeping the CO2 level from going any lower then 190 ppm. One intriguing possibility they bring up comes from a paper (Pagani et al., 2009) by Mark Pagani at Yale, and his colleagues at the Carnegie Institution in Stanford and at the University of Sheffield who claim that plants stop effective photosynthesis if CO2 levels fall below 190 ppm, depriving the carbon cycle of two sources of removal of atmospheric CO2; photosynthesis, and a more subtle plant activity called biologically enhanced silicate chemical weathering. The mechanisms of these two processes are interesting. Continue reading

Carbon Storage Increases Continuously as Trees Grow

by Stephen Johnson

Though it has been assumed that the rate of carbon accumulation declines with the age of an individual tree, little empirical evidence has been produced to support this assumption. Understanding how carbon storage capacity changes throughout the life of the tree is important in modeling carbon dynamics in forests, which can be used to determine how forests will contribute to climate change mitigation plans. Net primary productivity is well known to decline in even-aged forests, as does mass gain per unit leaf area. However, few forests are completely even-aged, and many are subjected to selective logging that removes the largest trees. Proper modeling of the amount of carbon lost through this logging can be used to more accurately price carbon credits for the preservation of natural forests, aiding efforts to keep them intact. In order to determine how carbon storage rates change with tree age, Stephenson et al. (2014) collected data from long-term monitoring plots in tropical and temperate areas across the globe. By measuring the diameter of each tree and using allometric equations, the researchers determined how much carbon was being stored over time. They found that while stand productivity declined with age, individual tree carbon gain rate increased, with no signs of declines at any age. Continue reading

Make Rainforests Pay

by Jackson Cooney

Deforestation significantly impacts our world’s climate. Within the last 40 years, one billion acres of tropical forests have been cleared, contributing to a massive increase in overall CO2 levels. Because forests store huge amounts of carbon, cutting or burning them releases their stored carbon back into the atmosphere where it mixes with oxygen to create CO2. CO2 increases at an annual 12 to 15 percent due to deforestation. Although there are economic incentives to cut down these forests, for timber, farmland and mining sites, there may be a greater incentive to preserve them. Forest carbon reserves can be monetized and traded or sold to offset releases by companies that produce greenhouse gases. This benefits companies that need these reserves to stay below a polluting limit set by the government. The offsets are subtracted from their emissions, keeping them within the legal limit. Revenues can then be used to support energy efficiency or energy saving projects. Until recently, it was difficult to quantify “emissions avoided by not destroying tropical forests”. However, techniques have been implemented to quantify the emissions that would be saved, specifically, a process that protects an acre of forest, even if the specific acre in question is destroyed. The proceeds of the sale would then be returned to the local communities. Continue reading

Hierarchical Responses of Plant-Soil Interactions to Climate Change

by Makari Krause

Ecosystems provide a multitude of services to humans, but one that will continue to grow in importance as climate change progresses is terrestrial carbon storage. In their paper, Bardgett et al. (2013) develop a framework for understanding the multiple mechanisms through which climate indirectly impacts the carbon cycle. These mechanisms are broken into three categories: individual responses, community reordering, and species immigration and loss. Individual responses only include changes to individual organisms without any alteration of the larger communities in which they live. While the individual responses occur in the short term, in the long term (years to decades) observable changes will occur within entire communities. This community reordering involves changes in the abundance of certain species but not the complete extinction of species or the invasion of new species. If the time period is extended even further there will be shifts in species resulting in the invasion of new species and the extinction of old ones. Each of these responses alters interactions between soil and plant communities and has associated implications for the global carbon cycle. Continue reading

The Effects of Deep Ocean Carbon Sequestration on Different Oceanic Locations

Methods to mitigate global warming have been ineffective thus far. For this reason, geoengineering methods to combat climate change have become a topic of much interest. Because the ocean holds a significant amount of anthropogenic carbon, deep ocean carbon sequestration is proposed to be a long-term solution to reducing the amount of carbon accumulation in the atmosphere. However, this solution also enhances ocean acidification at the seafloor. The authors study the effectiveness and side effects of CO2injection at various locations using an Earth model system. They compare the effects at the injection sites to the effects that would occur without using this mitigation method at those sites. The authors conclude that sequestration of CO2 was more effective under climate change and with larger overall emission, but poorly chosen sites that are shallow and or less accessible to the ocean can exacerbate future climate change. There are also many obstacles to using this method: a lack of public acceptability, costly and under-developed technologies for ocean CO2 storage, and a lack of complete evaluation of the benefits and consequences. The authors conclude that more thorough research is needed before the method is employed. —Michela Isono
Ridgwell, A., Rodengen, T., Kohfeld, K. 2011. Geographical Variations in the Effectiveness and side Effects of Deep Ocean Carbon Sequestration. Geophysical Research Letters 38, doi:10.1029.

            The rising accumulation of carbon in the atmosphere has proven to affect the planet detrimentally . Methods to mitigate these effects have therefore been proposed and studied. Because the ocean holds a significant amount of carbon, deep ocean carbon sequestration is a specific technique of geoengineering. This method injects liquefied CO2thousands of meters deep into the ocean, where the carbon would sink and be stored. The geologic storage of CO2 in the ocean serves to prevent CO2 from entering the atmosphere and perpetuating the effects of global warming.  
            Methods: A low resolution Earth system model (GENIE) is used to represent ocean circulation and carbon cycling. Five models are used in total: a bathymetry of the Earth system model is used to track measurements of ocean depth; an observation model based on data-estimated observations from other studies; a control model based on a 10,000 year spin-up under pre-industrial boundary conditions which is continued to year 2010 where levels of atmospheric CO2are based on historical data; a model based on model-estimated distributions of water-column integrated anthropogenic CO2 inventory for year 1994; and an experimental model that incorporate SRES emission scenarios for years 2100 and 2000 where 10% of the emissions are directed towards the ocean and the other 90% enter the atmosphere. Seven location points for injection were used: Bay of Biscay, New York, Rio de Janerio, San Francisco, Tokyo, Jakarta, and Bombay. These points represented the Antlantic Ocean, the Pacific Ocean, and the Indian Ocean. The injected CO2, once dissolved, is referred to as Dissolved Inorganic Carbon (DIC).
            Results and Discussion: CO2 that is injected at the ocean floor instead of being released into the atmosphere man interact with CO2 taken up at the ocean surface. Sequestration efficiency is therefore considered in the context of how much CO2 would invade the ocean from the atmosphere. In the San Francisco location, DIC extended outward from the injection point but there was also a reduced DIC in the North Atlantic because less CO2was taken up from the atmosphere. Higher DIC concentrations were found in the Pacific, but there was also a reduction in the amount of calcium carbonate saturation and an increase in the amount of seafloor area that had unsaturated conditions. However, in the Atlantic, the reduction of atmospheric CO2increased the amount of seafloor area that had saturated conditions. 
            Data regarding the variation in effectiveness of CO2 depletion and relative mitigation of the surface ocean acidification as a function of time, injection depth, and ocean sector demonstrate that carbon sequestration can fail to work. The Pacific and Indian Ocean point of injection sites were more likely to fail and result in a negative sequestration at year 3000 compared to unmitigated atmospheric CO2 release. However, the Atlantic injection sites did not have negative sequestration even though there were more shallow and intermediate ocean depth levels within this location.
            Sequestration efficiency was mapped to visualize the retention of injected CO2 in the entire ocean for the release at each grid point. The relative efficiency of carbon sequestration in percent (RE) at the beginning of the time period and located away from shallow continental margins was more or less the same at over 70%. However, later in the millennium, many inter-basin gradients in CO2 retention developed and RE approached zero because the carbon equilibrium was reestablished between the ocean and atmosphere.
            In locations where climate change was strongly prevalent, RE was enhanced.  In this case, carbon mitigation led to lower CO2 in the atmosphere and decreased the temperature of ocean surfaces. This increased the solubility of CO2 and improved CO2 uptake at the ocean surface. RE was higher for greater emissions. This means that carbon buffering is reduced when more CO2 is released and absorbed by the ocean surface. Thus, the results indicated that CO2 injection improved the ability for uptake from the atmosphere. Locations that included shallow sites and sites that are not well connected to the entire ocean exhibited an RE < 0.0.
            The choice of CO2injection site was also analyzed based on levels of under saturated waters. At year 2100, there was little changed by injection in the NW Pacific compared to the unmitigated case. Injections in the SE Pacific and S Atlantic experienced a 10% additional increase in the seafloor area that was under saturated. By the end of the millennium, injection led to less than a 2% increase in additional under saturated seafloor area.
Conclusion: Sequestration of CO2was more effective under climate change and with larger overall emissions. For higher emissions, the naturally occurring CO2 buffer of ocean surface waters is depleted faster. Overall, RE is better than 70% by year 2100 and in certain places can stay above 50% by year 3000. Poorly chosen sites that are shallow and or less accessible to the ocean can exacerbate future climate change. Injection in the deep NW Pacific (a high efficiency site) minimizes the exacerbation of under saturated seafloor conditions. There are many practical constraints that would limit the use of this geoengineering technique such as negative environmental impacts, harmful effects on organisms, and the method’s effect on other associated biotic impacts still need further research and analysis. 

Effects of Multiple Interacting Disturbances and Salvage Logging on Forest Carbon Stocks

Forests contain approximately 80% of aboveground terrestrial carbon. Therefore, minor alterations to carbon stocks or cycling in forests ecosystems may exacerbate global warming by increasing atmospheric carbon dioxide levels. Yet, current climate change is expected to increase the severity and frequency of stand-replacing disturbances such as wildfire and windthrow, which will ultimately decrease ecosystem carbon stocks over large areas for several decades. Previous studies have assessed the effects of individual disturbance on forest carbon storage. However, the consequences of multiple, interacting disturbances are relatively unknown. Using field data and statistical analyses, Bradford et al. (2011) quantified the changes in carbon stocks in ecosystem carbon pools (live biomass, snags, down woody debris, forest floor, and total ecosystem) that resulted from blowdown from windstorms, post-disturbance salvage logging, and wildfire in a forest in Northern Minnesota. Each disturbance was analyzed individually and in combination with one another. The authors found that total live carbon and carbon in live trees were highest in the control plot (no disturbance) and lower in all other treatments. Carbon in understory biomass was highest in the blowdown followed by salvage logging followed by fire plot (BSF). Carbon in snags and dead woody material was highest in the fire treatment while carbon in down woody debris and the florest floor was highest in the blowdown treatment. Total ecosystem carbon was highest in the control treatment, intermediate in the blowdown and fire treatment, and lowest in the blowdown and fire (BF) and BSF plots. Both blowdown and fire disturbances resulted in roughly equal decreases in live carbon and total ecosystem carbon. Fire further decreased carbon in the forest floor and down woody debris after blowdown, resulting in additional total ecosystem carbon losses. Salvage logging and fire after blowdown demonstrated similar results. Overall, these results indicate that increasing disturbance frequencies may challenge land management efforts to sustain and enhance ecosystem carbon stocks.—Megan Smith

Bradford, J.B., Fraver, S., Milo, A.M., D’Amato, A.W., Palik, B. Shinneman, D.J., 2012. Effects of Multiple Interacting Disturbances and Salvage Logging on Forest Carbon Stocks. Forest Ecology and Management (267), pgs. 209 – 214.

The study was conducted in Northeastern Minnesota along the Southern edge of the North American boreal forest ecotone, and within the Superior National Forest. On July 4, 1999, a large derecho (a widespread, straight-line windstorm) affected over 200,000 hectares of the Superior National Forest. After the storm, the US Forest Service began salvage logging operations to reduce fuel loads and mitigate wildfire. Salvage logging occurred between the fall of 1999 and the fall of 2002. Despite these efforts, a section of the region was burned by the Ham Lake Wildfire in 2007. Patchy, overlapping disturbance patterns resulted in five “treatments:” undisturbed control, blowdown only (B), fire only (F), blowdown followed by fire (BF), and blowdown followed by salvage logging followed by fire (BSF). Unburned salvaged areas were unidentifiable. The authors examined mature jack pine (Pinus banksiana) communities. A map displaying the location of the 1999 blowdown, the 2007 wildfire, and the study site was constructed.

Bradford et al. established six study sites in each study plot, creating 30 sites total. Eight of these sites contained previous data from an earlier investigation and were included in the author’s study. The remaining 22 sites were randomly selected. Although the authors lacked pre-disturbance data for most of their sites, they conducted comparisons of treatment stand structures and reconstructed structures for the other treatments (based on deadwood pools) with the plots with pre-existing data. As a result, the authors confirmed that all the sites were comparable regarding pre-disturbance stand structure and successional stage. Randomly selected sites were then ground-truthed for adherence to the expected forest type and disturbance combination. Within each site, 6–10 circular plots (200-m2) were established along a 40 x 40 m grid that originated from a randomly chosen starting point, creating 239 plots total.

Within each circular plot, standing live and dead trees (diameters greater than 10 cm at breast height), and saplings (stems sizes greater than 2.5 cm and diameters less than 10 cm at breast height) were recorded by species and diameter. Stems of shrubs and tree seedlings (stems smaller than sapling class) were tallied by species within a 10-m2 circular plot centered within each 200-m2 plot. Additional seedling data were collected in in 10-m2 plots located equidistant between each 200-m2 plot, resulting in 14 – 20 seedling plots at each site. Downed woody debris (DWD) on each plot was inventoried. Diameters of all DWD with measurements greater than 7.6 cm were recorded along a 32-m transect that passed through the middle of each 200-m2. The authors also collected samples of herbaceous vascular plant material, forest floor material, and soils at a set location within each 200-m2 plot.

The biomass of living and intact standing dead trees was calculated for all woody stems greater than 2.5 cm in diameter and breast height. The authors used species-specific allometric equations that were regionally derived. The biomass of broken standing dead trees was estimated using taper functions to determine large and small end diameters. Then, a conic-paraboloid formula was applied to determine the volume of the intact portion of the tree. Volume was converted to biomass using species-specific density values for decay class I taken from another author’s study. For unidentifiable standing dead trees, the authors used the average decay class II densities from all species present. Shrub and tree seedling biomass was calculated using species-specific allometric equations. Biomass calculations for these components included stems, roots, branches, as well as foliage, if it was alive. Dead woody debris biomass was calculated using Van Wagner’s formula. This formula was applied to the planar intercept data, adjusting for species and decay class-specific densities. The volume of coarse woody debris in decay class IV or V was adjusted for collapse using collapse ratios of 0.82 and 0.42. Carbon content was calculated from total biomass using species-specific values. Additionally, carbon was assumed to compose 50% of biomass for shrub species and unidentified down woody debris.

Separate mixed-model analyses of variance (ANOVA) were used to assess differences in carbon pool sizes among treatments. Disturbance combination was treated as a fixed effect and site was treated as a random effect. Analyses of variance was also calculated for carbon stored in live trees, understory (herbaceous plants, shrubs, and seedlings), live biomass (sum of live trees and understory), down woody debris (DWD), snags, dead woody material (snags plus DWD), forest floor, soil, and total ecosystem carbon (sum of live biomass, deadwood, forest floor, and soil). When the authors detected significant disturbance effects, post hoc Tukey’s honest significant difference tests were used for pairwise comparisons between disturbance types. All data were checked for normality and transformed before statistical analyses were undertaken.

Brandon et al. found that carbon in live biomass was stored primarily in live trees. Total live carbon and carbon in live trees were highest in the control plot (104 MgC ha-1) and lower in all other treatments (from 1 MgC ha-1 in the BSF plot to 21 MgC ha-1 in the blowdown treatment). Carbon in understory biomass was higher in the BSF treatment (1.3 MgC ha-1) than the control, blowdown, or fire treatments (0.2 to 0.6 MgC ha-1). Carbon in snags was much higher in the fire treatment than other treatments (53 MgC ha-1), and the BF treatment (19 MgC ha-1) was higher than the BSF treatment (1.7 MgC ha-1).

Carbon in DWD was highest in the blowdown stands (35 MgC ha-1), intermediate in the BF treatment (21 MgC ha-1), and lowest in all other treatments (9–10 MgC ha-1). Carbon in all dead woody material (snags and DWD) was highest in the fire treatment (62 MgC ha-1) and lowest in the BSF treatment (11 MgC ha-1). Carbon stored in the forest floor was highest in the blowdown treatment (35 MgC ha-1) and lowest in the BSF treatment (9 MgC ha-1). Furthermore, soil carbon means were not significantly different among treatments. Total ecosystem carbon was highest in the control treatment (177 MgC ha-1), intermediate in the blowdown and fire treatments (122 and 106 MgC ha-1), and lowest in the BF and BSF treatments (66 and 40 MgC ha-1).

Differences in carbon pools suggest that individual natural disturbances (blowdown and fire) resulted in similar decreases in live carbon (83 and 91 MgC ha-1) and total ecosystem carbon (55 and 71 MgC ha-1). Blowdown increased DWD carbon by 25 MgC ha-1 and forest floor carbon by16 MgC ha-1 and had no significant effect on sang carbon. However, fire increased snag carbon by 40 MgC ha-1. Compared to blowdown alone, fire following blowdown decreased both DWD and forest floor carbon by another 14 and 22 MgC ha-1, and resulted in additional total ecosystem carbon losses of 56 MgC ha-1. Similarly, salvage logging and fire after blowdown decreased carbon in both DWD and forest floor by another 26 and 39 MgC ha-1, and caused additional ecosystem carbon loss of 83 MgC ha-1 when compared to blowdown alone. A figure displaying carbon stocks for individual carbon pools and total ecosystem carbon for forest stands in each treatment was constructed, as was a figure demonstrating the consequences of windthrow, salvage logging, and wildfire on ecosystem carbon stocks.

These findings indicate that all combinations of disturbances resulted in lower total ecosystem carbon than the undisturbed control. Additionally, the results demonstrate that individual disturbances (wind and fire) resulted in similar shifts of carbon from live biomass to detrital pools, as well as similar losses of total ecosystem carbon. However, blowdown shifted live tree carbon into downed woody debris and forest floor pools while fire shifted this carbon into snags, which have slower decomposition rates than downed wood or forest floor. Total ecosystem carbon loss was attributed to the amount of carbon immediately lost from trees.

Overall, the authors’ results demonstrate that secondary major disturbances can cause substantial additional decreases in ecosystem carbon, though the magnitude may vary depending on the time between successive disturbances and disturbance types. Furthermore, the original blowdown disturbance increased carbon stored in DWD and forest floor, providing larger surface fuel loads that increased burn severity and carbon loss. Although forest floor and DWD carbon pools were elevated after the blowdown, the fire released all the carbon added to the litter in the forest floor and more than half of the carbon added to DWD. Salvage logging also modestly enhanced carbon losses. Post-blowdown salvage logging prior to fire decreased carbon in DWD to control levels, removing all of the carbon added to DWD in the blowdown. It also resulted in less carbon stored in snags. Yet, salvage logging did not significantly affect total ecosystem carbon despite its effects on individual carbon pools.

In conclusion, forest managers must address the issue that increasing disturbance frequencies may counteract efforts to sustain and enhance ecosystem carbon stocks, thereby exacerbating climate change by releasing more carbon into the atmosphere.

Ocean Iron Fertilization: A Viable and Significant Geoengineering Method Limited by Misplaced Concerns and Policy Restrictions

The ocean is a major player in determining global climate, partly because they regulate the amount of CO2in the atmosphere, and hence, strongly influence the greenhouse effect. However, since anthropogenic CO2 has altered the natural carbon cycle, a potential mitigation is to stimulate the ocean’s uptake of CO2. Ocean iron fertilization (OIF) is a particular method that has received much attention within the scientific community. Naqvi and Smetacek (2011) discussed previous OIF hypotheses and experiments, and analyzed results. They then addressed opposition to OIF and stated common arguments against the technique. Threats to OIF research were also discussed. Naqvi and Smetacek addressed their own proposal for an OIF experiment- LOHAFEX. Naqvi and Smetacek stated that their research allowed for significant findings about plankton ecology and that restrictions on it prevented important information from being discovered. The authors opposed commercialization of OIF and concluded that OIF research should not be highly regulated. —Michela Isono
Naqvi. S., Smetacek, V., 2011. Ocean Iron Fertilization. A Planet For Life 1, 197–205.

The Ocean’s Role in Combating Climate Change and Supporting Experiments
The oceans’ ability to absorb CO2is very important to combat global warming; oceans hold approximately 50 times more CO2 than the atmosphere. The amount of CO2 in the atmosphere now equals a third of the total carbon in all terrestrial vegetation, equivalent to about 100 parts per million/volume (ppm/v) higher than in preindustrial times. The authors support research for geoengineering methods to decrease the amount of CO2 in the atmosphere, particularly, the use of the biological carbon pump in the ocean. They introduced trace amounts of iron to nutrient-rich regions of the ocean in order to stimulate the growth of phytoplankton (microscopic organisms that consume carbon dioxide and release oxygen). Iron is used because it is the limiting nutrient for phytoplankton growth in some parts of the ocean. Phytoplankton die and sink after a bloom. Carbon is thus transferred to the deep ocean and sea floor.
Ocean iron fertilization experiments were first used in the mid 1900s to analyze ecological and biogeochemical phenomena in the ocean, explaining the inconsistency of low phytoplankton efficiency in three large, nutrient-rich regions: the sub-arctic Pacific, the Equatorial Pacific, and the Southern Ocean at both tropical and polar latitudes. It was hypothesized that low phytoplankton growth and productivity was due to low supply of iron. Additionally, in the last Ice Age in northern Europe and North America, the concentration of CO2 in the atmosphere was 100 ppm/v lower than that of the previous century. A large increase of iron to northern Europe and North America during the ice age would have increased phytoplankton productivity and removed more CO2 in the deep ocean compared to the warm, wet periods that followed. The introduction of iron to ocean surfaces to increase the removal of CO2from the atmosphere was termed the “iron hypothesis.”
Numerous studies confirmed parts of the iron hypothesis in regions with sufficient nutrients but low-productive phytoplankton. The studies increased the growth of phytoplankton most of which were diatoms (a major group of algae and the most common type of photoplankton). These diatoms had a protective shell made of silica, and died and sank as a group. The European Iron Fertilization Experiment (EIFEX) was done to confirm this natural diatom process. The experiment took place in an oceanic eddy (circular current) with a closed core that was 100 km wide and 3,500 km deep; oceanic eddies are important because they supply major areas of biological and physical activity. Iron was added to the eddy and a large bloom occurred that had the most diatom species in the ocean’s surface layer. Many phytoplankton cells then grouped together and sank to the deep ocean. Even with many zooplankton (small invertebres) that consume diatoms, the feeding on the diatoms was unexpectedly low. This experiment confirmed the diatom’s natural process.
Previous OIF studies were conducted in low-productive oceanic regions located away from natural sources of iron. These studies investigated large, spiny and thick-shelled diatoms. In 2005, India and Germany conducted a joint OIF experiment called LOHAFEX. The experiment focused on a different diatom population that lived in the Southwest Atlantic part of the Antarctic Circumpolar Current. These diatoms were smaller in size, had thinner shells, and grew faster. They also died and sank as a group after they bloomed. This region had productive phytoplankton and a significant amount of iron in its coastal waters. A study that focused specifically on the distribution of this particular diatom species found the diatoms extended eastward about 10˚W. Other sediments left during the previous glacial period proved an eastward allocation that spanned the Atlantic sector. This suggested that these diatoms seized the carbon missing from glaciers from the Ice Ages.
 The authors turned in the LOHAFEX proposals in 2006. After other scientists in India and Germany reviewed the proposal, the authors were granted ship access and the equivalent of $4 million in funds. Afterwards, The Alfred Wegenger Institute in Germany and India’s National Institute of Oceanography created a memorandum of understanding (MoU) for their shared experiment. The leaders of each institute signed the MoU in October 2007. Other scientists from institutions in Italy, Spain, the United Kingdom, France, and Chile also joined the team. In total, the LOHAFEX team included 49 scientists. The National Institute of Oceanography (NIO) held a two-week training course in January and February 2008 and a preparation practicum in April 2008 that trained the people who measured these processes. These training sessions were important because open ocean experiments provide crucial information for developing models of ocean ecosystem functioning that help forecast how climate change will affect oceans and oceans’ organisms.
Opposition to OIF
 Naqvi and Smetacek acknowledged objections to OIF geoengineering. After the first successful OIF experiments in the mid-1990s, various companies publicized that they would use OIF to obtain carbon credits on the market through the Kyoto Protocol; The Kyoto Protocol is a set of rules to the United Nations Framework Convention on Climate Change (UNFCC) that combats global warming, and the UNFCC is an international environmental treaty that aims to achieve safe levels of greenhouse gas concentrations in the atmosphere. The media did not differentiate small-scale, scientific experiments and large-scale commercial enterprises. This caused a negative view of OIF within the public domain.
Other arguments against OIF were based on previous reports about heavy metal pollution (fertilizing the ocean with nitrogen and phosphorous) and eutrophication (excessive plant growth). The perceived consequences were damaged aquatic and terrestrial organisms, and lack of oxygen for local organisms, respectively. Additional concerns regarded animal deaths and human health resulting from worsened water quality and contaminated aquatic species. The authors confirmed these consequences. However, the authors did not validate the drawn comparison between heavy metal pollution and eutrophication (which consisted of constant, large doses of metals in coastal areas), with their idea (adding trace amounts of iron to the deep ocean). The authors argued that if the iron dose were small and sporadic it would not harm the environment.
The potential bloom of toxic species was another argument against OIF. The authors stated the majority of toxic species, dinoflagellates, usually arose in shallow waters and were absent in the open ocean. However, the authors stated that some toxic species, Pseudo-nitzchia, did arise in OIF experiments. These toxic species usually occurred in coastal upwelling regions. Negative effects to marine shellfish and animals were reported from the West and East Coasts of the United States and the province of Prince Edward Island in Canada. However, other accounts of toxic algal blooms in the Gulf of Mexico and the coast of Portugal did not have negative affects of marine mammals and birds. The authors stated further experiments were necessary to test the risks of toxic species in OIF conditions. 
Threats to OIF Research and the LOHAFEX Experiment
            The publicized statements of corporate OIF plans stimulated environmental groups, governmental organizations, and nongovernmental organizations to oppose implementing OIF plans. Consequently, in May 2008, the Conference of the Parties to the Convention of Biological Diversity (CBD) necessitated extensive prior research before implementing any ocean fertilization techniques. They also demanded that the techniques be heavily controlled. The CBD statement advised parties to follow the decision of the London Convention on the Prevention of Marine Pollution by Dumping Wastes and Other Matter. This CBD statement was very controversial. Thus, the Contracting parties to the London Convention and the London Protocol discussed ocean fertilization. In October 2008, they ruled that ocean fertilization is only permitted for scientific research, and each proposal will be reviewed on a case-by-case basis. The authors thus decided to proceed with their LOHAFEX experiment.
The LOHAFEX Experiment and Results
            Despite significant protest from multiple German NGOs, the LOHAFEX experiment was deemed acceptable by the German government. The team received permission to use an oceanic eddy with a closed core in the Southwest Atlantic waters. Ten tons of granular iron sulphates dissolved in seawater were introduced to a 300 square kilometer area. The authors noted the amount of iron used was within the natural amount of iron in unpolluted coastal waters. The team tracked the iron-fertilized region for 38 days. The fertilized region remained within the eddy for 23 days and was then expelled. The region then spread and dissolved.
            The results of the LOHAFEX experiment showed different results than the aforementioned OIF experiments conducted in regions with low productive phytoplankton. Six important results were found: 1) diatoms were absent and phytoplankton biomass was composed mainly by small flagellates; 2) strong grazing by zooplankton prevented phytoplankton’s biomass from exceeding 1.7 milligrams of chlorophyll a per cubic meter (chlorophyll is critical for plants to obtain energy from light and measuring the amount of chlorophyll a is a good measure of phytoplankton biomass); 3) bacterial biomass was low despite primary productivity being doubled; 4) the uptake of CO2 was moderate; 5) small amounts of organic substance went to the deep ocean, and 6) iron fertilization did not effect the making of other greenhouse gases that destroy the ozone (carbon and halogen compounds).

            Two important inferences were drawn from these results. The first was that introducing iron to iron-deficient regions in the Southern ocean does not increase the size of the phytoplankton bloom; grazers controlled the size. The second implication was that OIF’s ability to remove anthropogenic CO2 was lower than expected. The authors stated that more issues with OIF methods must be addressed. These issues encompassed the role of trace elements, the relationship between phytoplankton and zooplankton during time periods when zooplankton supply is lower, and the effect on the food chain with long-term OIF methods. The authors recognized the importance of OIF research for the discovery of important benefits. They believed commercialization and misplaced concerns would limit scientific research. The authors opposed OIF commercialization and stated that future research should be funded by carbon taxes instead of a carbon credit market. They concluded that scientific research should not be highly regulated. 

CO2 Sequestration in Various Indus-trial Cement Products

The concentration of CO2 in the atmosphere has increased dramatically, which is causing irreversible change to global climate systems.  Carbon capture and storage is one course of action proposed to remove some of this excess CO2 and decrease the amount of new CO2 being emitted.  It is known that calcium will react with CO2 under certain conditions and create calcium carbonate<!–[if supportFields]> XE “calcium carbonate (CaCO3)” <![endif]–><!–[if supportFields]><![endif]–> (CaCO2), a stable compound that sequesters the carbon in a way that it is not reintroduced into the atmosphere.  Furthermore, there are several industrial, calcium-carrying materials that can participate in this reaction.  Previous research has shown that concrete can take up CO2 as carbonate while it is curing.  The incorporation of CaCO2 into the concrete makes the material stronger.  It also makes cement more compatible with wood materials for the production of products like wood-cement particleboard.  The carbonation also reduces shrinking by about 50% as cement sets and makes the material less permeable to water.  Currently, this practice is not used because the cost of producing CO2 is so high that it is not economically feasible.  However, it has been proposed that if recovered CO2 were used, then this option would become economically possible with the introduction of a carbon credits or carbon tax systems.  Monkman et al. (2010) compared different scenarios for using emitted CO2for this process and looked at the environmental and economic viability. —Anna Fiastro
Monkman, S., Shao, Y., 2010. Integration of carbon sequestration<!–[if supportFields]> XE “carbon sequestration” <![endif]–><!–[if supportFields]><![endif]–> into curing process of precast concrete. Civil Engineering. DOI:10.1139/L09-140.

 The authors compared recovered CO2to untreated industrial flue gas emissions in their ability to carbonate 4 different cement products.  The recovered CO2 was imitated with highly concentrated and pressurized CO2.  For each exposure, a continuous supply was used, causing constant pressure and CO2 concentrations to mimic flue gas which is emitted at a pressure higher than atmospheric pressure. The cement product was closed in a chamber with the pressurized gas and allowed to take up the CO2.  After the designated period of time the chamber was emptied and refilled with flue gas.  This process was repeated about seven times, and each time the carbon uptake gradually slowed down as it reached saturation.  The amount of carbon taken up was quantified by the percent gain in mass of the cement.
Concrete masonry units (CMU) are one industrially produced product that was examined.  CMU were found to be the ideal candidate for carbon uptake because it is porous and already cured in a closed camber, making the addition of a gas easy.  Concrete paving stones were also looked at.  They are not subjected to any special curing scheme so they could easily be placed in a large sealed room filled with gas for the carbonation treatment.  Fiberglass mesh reinforced cement is a product that is cured with high pressure and moisture.  Because if this, a large surface area to volume ratio is necessary, which also lends itself to carbon uptake.  The last product examined in the study was cellulose<!–[if supportFields]>XE “cellulose” <![endif]–><!–[if supportFields]><![endif]–> fiberboard, used in place of asbestos cement.  The curing steps for this material can also easily be replaced by carbonation curing, giving the benefit of hydration of the material and carbon sequestration<!–[if supportFields]> XE “carbon sequestration” <![endif]–><!–[if supportFields]><![endif]–>.  Both the fiberglass mesh cement and cellulose fiberboard benefit from a lowered pH, protecting the material from alkali corrosion.
All four of these materials would benefit in strength and durability from carbonation, and their curing processes could easily be replaced or supplemented by carbonation curing.  In all cases the uptake from recovered CO2 was greater than uptake from flue gas. 
It is also important to compare the energy and CO2 penalties for recovering, compressing, and transporting the CO2 in order for it to be used.  When this is taken into consideration, recovered CO2 is still the most viable option, because it is already at high concentrations.  The compression and transportation of flue gas makes it only feasible if the curing process occurs on site.  The transportation associated with recovered CO2 can also be compared to other capture and storage methods, such as geological storage, which would result in equal or more transportation emissions.
Part of the analysis of processing emissions is the comparison of carbonation curing with steam and autoclave curing, the methods predominantly used in the industry.  The emissions from carbonation curing are less than one tenth of those associated with steaming and autoclaving.  This method is also attractive if one takes into account the possible trading value of carbon and improved technologies reducing energy use in production phases.
One last analysis was done looking at the carbon uptake of ladle slag<!–[if supportFields]> XE “slag” <![endif]–><!–[if supportFields]><![endif]–> fines as a replacement for sand.  This was done using a different CO2exposure process than the other materials.  The particulates were exposed to gas made up of 50% CO2 at atmospheric pressure.  This was meant to replicate flue gas without the compression step that is so energy expensive.  The material was found to have a modest carbon uptake of about 10% after almost 60 days.  This is not thought to be the best opportunity for carbon sequestration<!–[if supportFields]> XE “carbon sequestration” <![endif]–><!–[if supportFields]><![endif]–> but other calcium-rich slags may serve this goal more affectively.

Biochar’s Impact on Greenhouse Gas Fluxes: Different Gas Fluxes are Cor-related with Different Parameters

The release of greenhouse gases from agricultural soil is important in the light of climate change. However, at the same time, the study of emissions from agriculture needs to take into account many variables, increasing the difficulty of pinpointing exactly what is causing the agricultural flux of greenhouse gases. Kurhu et al. (2011) wanted to study the impact of biochar on the release of greenhouse gases from soil in Southern Finland. They found that there were differences between the levels of carbon dioxide and nitrous oxide emissions between soils to which biochar had been added and soils to which it had not. Furthermore, although they found that biochar increased methane uptake, and also became aware of many limitations of studying biochar’s impact on the level of greenhouse gases released into the atmosphere.Nitya Chhiber
Bergstrom,I.,Karhu, K.,Matila,T.,Regina,K.,2011. Biochar addition to agricultural soil increased CH4 uptake and water holding capacity – Results from a short-term pilot field study. Agriculture, Ecosystems & Environment 140, 309–313.

Karhu et al. studied the affect of biochar on agricultural soil that was undergoing a process of five-year crop rotation. Plots were of mainly of two types: those with the addition of biochar and those without the addition of biochar. Fluxes of carbon dioxide, nitrous oxide, and methane were measured, and using linear method, related to soil water holding capacity, soil temperature, air temperature, and  grain yield.
Carbon dioxide emissions were positively correlated with temperature, however, the addition of biochar increased methane uptake by a great deal but had no effect on nitrous oxide and carbon dioxide fluxes.
Methane was an interesting case as it responded greatly to rainfall; when it rained and there was higher soil water content, there was a higher methane flux from soil into the atmosphere, especially when the soil was wet and there was no biochar in the soil.
In the literature, no pattern can be found between biochar and the fluxes of carbon dioxide and nitrous oxide across experiments due to the fact that the type of biochar used in each experiment varies. Other reasons that there may be no pattern is that nitrous oxide can be produced under both aerobic and anaerobic conditions, and that higher applications of biochar may be needed in soil to actually see a difference in the fluxes of these two gases.

Possible Negative Implications of Ocean Urea Fertilization

Since the industrial revolution, there has been an ever-increasing concentration of CO2in the atmosphere contributing to global climate change.  Ocean fertilization<!–[if supportFields]> XE “fertilization” <![endif]–><!–[if supportFields]><![endif]–> is one proposed method of carbon capture and storage<!–[if supportFields]> XE “carbon capture and storage (CCS)”<![endif]–><!–[if supportFields]><![endif]–>; it is the use of fertilizers to stimulating the growth of phytoplankton<!–[if supportFields]> XE “phytoplankton” <![endif]–><!–[if supportFields]><![endif]–> species that take up CO2 in their growth.  One fertilizer<!–[if supportFields]> XE “fertilizer” <![endif]–><!–[if supportFields]><![endif]–> being proposed is urea, a nitrogen<!–[if supportFields]> XE “nitrogen” <![endif]–><!–[if supportFields]><![endif]–> rich organic compound.  Unlike nitrogen fertilization, research of the effectiveness of urea as an ocean fertilizer is only being conducted by one laboratory at the University of Sydney, which has connections with Ocean Nourishment Corporation (ONC)<!–[if supportFields]> XE “Ocean Nourishment Corporation (ONC)” <![endif]–><!–[if supportFields]><![endif]–>, a company that has the patent on the procedure.  The environmental and social aspects of this procedure must be fully examined to determine if it a safe and effective solution for carbon sequestration<!–[if supportFields]> XE “carbon sequestration” <![endif]–><!–[if supportFields]><![endif]–> before it is implemented on a large scale.  Mayo-Ramsay (2010) discusses the process of urea fertilization, and its ability to reduce atmospheric levels of carbon and stimulate fisheries.  She also examines its possible effects on the Sulu Sea, the leading site being considered. —Anna Fiastro
Mayo-Ramsay, J., 2010. Environmental, legal and social implications of ocean urea fertilization<!–[if supportFields]> XE “fertilization” <![endif]–><!–[if supportFields]><![endif]–>: Sulu sea example. Marine Policy. 34, 831835.

Ocean urea fertilization<!–[if supportFields]>XE “fertilization” <![endif]–><!–[if supportFields]><![endif]–> utilizes a nutrient solution produced by mixing urea with other limiting nutrients.  This nutrient solution is then put in the ocean where it increases the abundance of phytoplankton<!–[if supportFields]>XE “phytoplankton” <![endif]–><!–[if supportFields]><![endif]–>, and the resultant uptake of carbon from the atmosphere.  This stimulation at the lowest trophic<!–[if supportFields]>XE “trophic”<![endif]–><!–[if supportFields]><![endif]–> level is thought to trickle up the food chain and increase marine productivity of larger fish.  The two benefits that are outlined are the sequestration<!–[if supportFields]>XE “sequestration” <![endif]–><!–[if supportFields]><![endif]–> of carbon and the increase in fish populations, which could help in the face of a global food shortage. 
Professor Ian Jones is the head of the Ocean Technology Group at the University of Sydney, the only laboratory conducting research on urea fertilization<!–[if supportFields]> XE “fertilization” <![endif]–><!–[if supportFields]><![endif]–>.  He also has interests in the Ocean Nourishment Corporation, an Australian commercial organization that has patented its urea fertilization technology.  While the company claims to have conducted research on its technique and possible implications, no peer reviewed scientific articles have been published.  The company did not consult the local governments or communities that would be affected by this experimentation.
Other scientific discussions and studies being conducted by independent groups have identified various possible dangers related to ocean fertilization<!–[if supportFields]> XE “fertilization” <![endif]–><!–[if supportFields]><![endif]–>.  Added fertilizer<!–[if supportFields]>XE “fertilizer” <![endif]–><!–[if supportFields]><![endif]–> can lead to the creation of hypoxic zones (areas void of oxygen) as well as the release of nitrous oxide<!–[if supportFields]> XE “nitrous oxide (N2O)” <![endif]–><!–[if supportFields]><![endif]–> (N2O).  This increase in nutrients can lead to an imbalance in the different species of phytoplankton<!–[if supportFields]> XE “phytoplankton” <![endif]–><!–[if supportFields]><![endif]–> and ecosystem composition.  There is also a question of whether or not such fertilization actually leads to carbon sequestration<!–[if supportFields]> XE “carbon sequestration” <![endif]–><!–[if supportFields]><![endif]–>.  While the phytoplankton blooms do take up CO2, the carbon must not be released back into the atmosphere in order for it to be an effective solution for climate change.  In this case, the dead material constructed from the carbon must sink to the bottom of the ocean, but evidence shows that the phytoplankton stay on or near the surface creating a scum. 
The proposed urea fertilization<!–[if supportFields]>XE “fertilization” <![endif]–><!–[if supportFields]><![endif]–> plant would pump urea into the Sulu Sea southeast of Asia.  This site was selected because it is a fairly enclosed body of water that lacks nutrients but has sufficient phosphorous.  While this might seem like a good location, the limited circulation can intensify the possibility of anoxic conditions with increased nutrients. 
The other proposed benefit of the program is increased marine productivity, which would supposedly stimulate the local fisheries.  Currently there is a vibrant aquaculture<!–[if supportFields]> XE “aquaculture” <![endif]–><!–[if supportFields]><![endif]–> industry in the region and long-term production of fish through this method has not been proven.  Even if there were increased productivity, the management of this fishery would become very complicated.  The proposed site in the Sulu Sea is bordered by a number of States.  The Ocean Nourishment Corporation has proposed a specific fishing license that would be necessary to fish in the waters affected by their plant, but would be nearly impossible to determine which fish were wild and which were grown under the influence of the fertilization<!–[if supportFields]> XE “fertilization” <![endif]–><!–[if supportFields]><![endif]–> conditions.  Such a license would also be detrimental to the local fisher<!–[if supportFields]> XE “fisher” <![endif]–><!–[if supportFields]><![endif]–>-people who rely on the fish for their survival, presenting a serious legal barrier to the viability and completion of this project.

Another legal concern is the distribution of the carbon credits obtained through the carbon sequestration<!–[if supportFields]> XE “carbon sequestration” <![endif]–><!–[if supportFields]><![endif]–>.  Currently the International Organization for Standardization is coordinating a system to validate and verify greenhouse gas accounting.  The benefits of the program would need to be quantified and distributed among the States and organizations participating in the project, but the number of States involved makes this process difficult to agree upon, implement, and regulate.