Ignorance Is Bliss

by Breanna Sewell

Retired NASA astrophysicist and former leader in humanist organizations, Jordan Stuart, discusses the willingness and ability of people to counter the effects of climate change in his 2014 paper, “Is Action to Mitigate Climate Change Possible Today?” He introduces the topic by addressing the unfortunate state of our planet in regards to increasing amounts of natural disasters, and then continues on to state that global climate change is undeniably caused by human activity. Stuart writes that scientists have done enough to prove that global warming is the cause of climate change and that anthropogenic greenhouse gases are the cause of global warming, therefore we, as a people, should admit that we are the cause of climate change. Continue reading

The Complications of Climate Engineering and International Law

by Emily Segal

As anthropogenic climate change continues to become an increasingly discussed social, political and environmental issue, some people are turning to climate engineering as a way to supplement the pre-existing strategies of mitigation and adaptation. In the paper reviewed here, Winter (2011) explores its relationship to international law. Geoengineering, or geological engineering, refers to the application of geoscience to shape our interaction with the earth. Some forms of geoengineering that have been around for a while are detrimental to the health of our planet. Examples include deforestation, the method of clearing forested land to create arable land for monocultures, and burning fossil fuels, a process that releases toxic substances into the atmosphere, which contribute to the greenhouse effect and speed up global warming. New forms of geoengineering, however, are different from these older forms because they do not encourage side-effects that are harmful to the environment. Instead, they have intended consequences that will help reduce climate change. Carbon capture and storage (CCS), a way of capturing CO2 after it is emitted and storing it in land, is an example of a more recent form of geoengineering that would aid in decelerating climate change. Solar Radiation Management (SRM) is another form of geoengineering intended to reduce climate change. SRM increases surface and cloud albedo, a kind of weather manipulation that could be effective if used on a large scale. Continue reading

Can Religion Figure Out Whether We Should Use Geoengineering?

by JP Kiefer

Clingerman and O’Brien (2014) believe that geoengineering has the potential to solve the disaster of climate change. Geoengineering is the process of changing the environment through any one of many diverse methods, like solar radiation management or fertilizing the ocean to create algae blooms as a means of combating climate change. Each of these methods has unintended side effects, but can be summarized as cheap, fast, and imperfect ways of reducing the effects of greenhouse gasses on the environment. Continue reading

The Implications of Geoengineering

by Jackson Cooney

A government-sponsored panel, assembled by NASA and other federal agencies, was assembled on February 10, 2015 to discuss the implications of using geoengin,,eering as a way to fight climate change and greenhouse gas emissions. Henry Fountain, writing in The New York Times summarizes as follows: geoengineering falls into two categories. One method captures and stores CO2 that has already been emitted. The other involves reflecting the sun’s rays back into the atmosphere so that less heat would enter the Earth. The first option has minimal risks, however it would be expensive and take time to see any noticeable effects. There would also be a need for more research in order to find a way to successfully store the CO2. The second option, solar radiation management, is more controversial. This involves dispersing sulfates into the atmosphere to reflect the sun’s rays away from Earth. This method is inexpensive and the effects are seen quickly, however it would have to be repeated many times. It would also do nothing to solve global problems related to CO2 like Ocean Acidification. Continue reading

Fertilizing the Ocean to Trap CO2

by Emil Morhardt

One of the ways scientists have hoped to suck CO2 out of the atmosphere is by adding nutrients to the ocean that are limiting the growth of photosynthetic phytoplankton. The idea is that with the proper nutrients (iron being the main one experimented with so far) the plankton would capture CO2 photosynthetically, convert it to biomass, die, then sink to the ocean floor, “exporting” the new carbon in their bodies to a place where it couldn’t have any effect on global warming. There are a number of posts in this blog dealing with those experiments under the category “Ocean Fertilization”; they haven’t worked very well because, among other things, instead of sinking to seafloor, the phytoplankton get eaten by zooplankton which metabolically convert them back into energy and CO2 which can then diffuse back to the atmosphere, or at least contribute to ocean acidification.

A fascinating paper just published in Science, examines the nutrients limiting the growth of the photosynthetic marine cyanobacterium, Prochlorococcus, in a much more interesting and comprehensive way than previously possible, and although it doesn’t directly speak to the feasibility of fertilizing the ocean to trap CO2 (sorry about the somewhat misleading title to this post) it greatly increases the potential sophistication with which such a goal could be pursued. 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. 

The Effects of Sulfate Aerosol Injection Across Various Stratospheric Locations

The detrimental effects of global warming have become increasingly apparent, and the current mitigation methods have proven insufficient. Therefore, geoengineering techniques have been proposed as the necessary means to combat global warming. Specifically, solar radiation management using the sulfate aerosol has been named the most effective solution. The authors analyze temperature and precipitation responses to stratospheric sulfate aerosol as a function of both latitude and altitude of release. They model the injection of the sulfate aerosol (comprised of H2S rather than the commonly analyzed SO2) in the Northern and Southern Hemispheres. The authors conclude that sulfate aerosol injections at higher latitudes reduce global mean temperature, precipitation, and total ozone. They also conclude that warming in the stratosphere follows cooling in the troposphere. —Michela Isono
Volodin, E., Sergey, V., Ryaboshoapko, A. 2011. Climate Response to Aerosol Injection at Different Stratospheric Locations. Atmospheric Science Letters 12, 381–385.

            Model: The climate model used is Earth system model INMCM. This model includes the general circulation of the atmosphere and oceans. It is used to determine the most effective injection circumstances in order to reduce changes in temperature and precipitation in the Arctic and on a global scale. The observed climate changes in the 20th century will also be reproduced in the model. The model also has a sulfate aerosol component that describes the formation of the sulfate aerosol particles and their removal by gravitational settling. H2S was chosen instead of SO2 because it is a gas with the highest sulfur content by mass, and it has a prolonged lifetime that enables greater dispersion before the aerosol particles are formed and the reduction in particle concentrations by coagulation. Lastly, the gravitational settling velocity is calculated using the Stokes-Cunningham formula:
vg= 109Ccunngd2p / (18 µ), where Vg is gravitational velocity (m/s), g is acceleration due to gravity (9.8 m/s2), d is particle diameter (m), p is particle density (1.63 g/cm3), µ is dynamic viscosity of air (µPa s) and Ccunn is a correction factor.
            Geoengineering scenarios: Six scenarios in the Northern and Southern hemispheres are used in this study. They are at different altitudes above the tropopause and within different latitudinal belts. Each hemisphere experiences a continuous injection of 2 Mt per year. The sulfur injection is continued for 30 year in each model where the level of atmospheric CO2 is constant at 288 ppb. The climate response was determined by the average temperature and precipitation over the latter 20 years. Each model was then compared to a control model with no inclusion of geoengineering. The climate response was calculated as the difference between the temperature or precipitation in the models with geoengineering compared to the control model without geoengineering. The annual mean values were calculated separately for the globe and Arctic (north of 65˚N).
            Results: Scenario 1, 2, and 3 with injections near the equator at 26–28, 22–24, and 20–22 km respectively, were the most effective. Scenarios with lower injections towards the poles were less effective for global cooling. It was determined that injections at higher heights ranging from 20–28 km lead to a higher concentration of gaseous H2SO4 rather than the aerosol. The level of global precipitation reduction and cooling were proportional. The total ozone loss was also proportional to aerosol mass and global cooling. The Arctic temperature change, however, was two times more than the global temperature change. The models also demonstrated significant aerosol concentration located outside of the injection region. The equilibrium aerosol mass in the atmosphere is reached after about two to three years, where the lifetime of the aerosol was 0.9 years. The equilibrium temperature and precipitation response was achieved after 10–15 years.
            The annual mean cooling over land was stronger than over the ocean. The strongest cooling was over high latitude land and sea ice, above 2˚. There was a decrease in precipitation by 5–10% over parts of Eurasia, and North and South America. In contrast, there was an increase in precipitation by 10–20% over Mediterranean, tropical, and subtropical regions. Overall, as the aerosol cooled the troposphere, the stratosphere warmed by 2–8˚. This was due to the aerosols’ absorption of small amounts of visible radiation in the stratosphere.
            Conclusion: The authors concluded that the best scenarios for geoengineering with sulfate aerosol was when the aerosol was injected at 26–28, 22–24, and 20–22 km in the latitudinal band 0–10˚. Additional conclusions were that cooling is greater over land and high altitudes, the injection of aerosols decreases global mean precipitation and total ozone, the cooling in the troposphere is followed by warming in the stratosphere, and an increase of diffuse radiation increases vegetation primary production.