If Wishes Were Horses . . .

How many headlines similar to this one have you seen in the past three month? Reading the article (or listening to the news report), you are told that some new breakthrough has been achieved, that the costs of the new technology will be manageable, and our climate crisis can be averted. If you continue to the end of the story, it may acknowledge that a few details remain to be worked out, but these will be inconsequential, and it can all happen with little or no change to our present lifestyles.

Beware! Responsible journalism must do more than hope for easy solutions and should consider the details more honestly, both the promising indications and the unfavorable ones. From the many possibilities in recent media, three examples will be addressed here: 1) industrial carbon capture technologies, 2) modifications to the upper atmosphere, and 3) energy production by nuclear fusion.

Carbon Capture and Storage (CCS):

Industrial technologies that fall under this category have the goal of capturing carbon dioxide from emissions from power plants and industrial facilities¹ or by directly removing it from ambient air.² The captured carbon dioxide may then be used for other industrial purposes or else permanently stored underground. The obvious appeal of these proposals is that they not only promise to reduce annual greenhouse gas emissions, but some might even remove CO₂ that is already in the atmosphere.

There are a great many companies around the world that are already using or developing carbon capture technologies.³ These processes include adsorption on solid surfaces, membrane gas separation, gas hydration, along with others. Each has its own capital costs of construction, its own monetary costs for operation, its own energy requirement per ton of CO₂ captured, and each has its own challenges for handling potentially hazardous chemicals. When the carbon dioxide has been captured, it is then compressed to a liquid for ultimate disposal. Some fraction of the currently captured CO₂ is used by petroleum companies for enhanced oil production, and some small fraction serves as feedstock for other industrial process. It is expected that in the future, the greater part of recovered CO₂ would transported via pipeline and then stored underground.

While claims of success are made by a number of industrial enterprises,^{3, 4} academic articles offer more nuanced views of the technology.⁵ These tend to discuss capital investments, efficiencies and costs involved, availability of suitable storage reservoirs, the possibility of accidents,⁶ environmental consequences, and potential difficulties in scaling up from demonstrations to large industrial complexes. There are currently no carbon capture facilities in operation large enough to make a difference. Above all, the energy costs needed to implement CCS are high. Depending upon the fuel and the technology used, between 10 and 40% of the energy produced by a fossil fuel power station would be required to implement the carbon capture process in its emissions.¹ There are also issues of subsidies, of political involvement, and of impacts to the often disadvantaged communities adjacent to projects.

Even More ambitious than the proposals described above are those which would remove CO₂ directly from the atmosphere.² These are advantageous in that they do not need to be located near any industrial source, and in principal they might remove greenhouse gases that have already been emitted. Direct extraction from the air has the significant handicap of much higher costs in both money and energy per ton of CO₂ removed. The theoretical minimum energy required to extract CO₂ from ambient air is about 250 kWh per tonne of CO₂, while capture from natural gas and coal power plants requires, respectively, about 100 and 65 kWh per tonne of CO₂.² As these projects do not produce energy, they will require power from other energy sources. A paper⁹ published by the Belfer Center for Science and International Affairs, at the Harvard Kennedy School, concludes: “By 2050, [direct capture from the air] appears likely to achieve removal equivalent to at most about 1% of current emissions of fossil carbon from energy and industry. It will thus make at most only a small contribution to meeting 2050 net zero targets. This illustrates the importance of focusing on emissions reduction wherever possible.” [Italics added]

The Infrastructure Investment and Jobs Act provides support for a variety of CCS projects, and the Inflation Reduction Act of 2022 encourages the use of CCS. Additionally, the IPCC Sixth Assessment Report¹⁰ includes carbon capture technologies among scenarios for addressing climate change. In spite of this public interest and political involvement, it is certain that the difficulties are many and varied, and the large scale deployment of carbon capture strategies, if it ever occurs, will be in the future and of minor significance in meeting the immediate climate crisis.

Modifications to the Upper Atmosphere:

Another proposal to avert disastrous warming would place aerosols in the Earth’s stratosphere to reflect a small fraction of the incoming sunlight back into space before it reaches and warms the surface of the planet.¹¹ Solar radiation modification (SRM), as this is called, would produce cooling similar to that which has followed major volcanic eruptions in the past. Aerosols might be injected into the atmosphere from custom aircraft, balloons, or even artillery. Sulfate particles are most commonly discussed as they are the principal emissions from volcanic events. It is important to note that the proposal does nothing to remove greenhouse gases from the atmosphere – it only reduces solar radiation reaching the earth’s surface.

Solar Radiation Modification has several attractive features. It is relatively cheap when compared to proposals for reducing the emission of greenhouse gases or for mitigating the expected effects of climate change. Quite a number of countries have or could develop the means to carry out the proposal. The effects if aerosol injection could appear rather quickly, even within a period of several months. Although it would be necessary to regularly replenish the atmospheric shield, this has a compensating advantage in that the effects could be rapidly reversible if this were needed.

As with any technology, SRM can be expected to have negative effects.^{11, 12} The warming effects of atmospheric carbon dioxide are world-wide, day and night, and at all seasons. Reflection of sunlight by aerosols is variable depending upon latitude, season, and hour of the day. These differences would inevitably lead to new climatic changes, and although these effects are being modeled, the accuracy of these predictions is difficult to asses.

Solar radiation modification would not remove CO₂ from the atmosphere, and so acidification of the ocean by this gas would continue. While higher levels of CO₂ in the air might be a benefit for agriculture, reductions in incident sunlight due to solar radiation modification might be a negative factor. A related and but poorly understood factor would be how the slight changes in the relative intensities of arriving infrared, visible, and ultraviolet light might affect the biosphere.

Because the cooling effects would be reversible, if for some reason the regular injections were halted, the surface temperature would rather quickly warm to what it would have been in the absence of any intervention. SRM might buy time, but in the long run, there would also need to be a significant reductions in greenhouse gas emissions. With cooling caused by radiation modification, ongoing efforts toward a permanent solution for global warming might falter. Other kinds of social problems can be imagined. Individual countries (or even large industries) might view SRM projects differently and would pursue their own interests aggressively Without some kind of international agreement or control, an “atmospheric war” is within the realm of possibility.

Current views about the future for atmospheric engineering are mixed. Some organizations, including some traditional environmentalists, insist that the current crisis is so acute that all possibilities must be pursued. Others are more cautious. Research to understand the possible outcomes of SRM is ongoing, and two small scale deployments were proposed to obtain data. These proposals, over Finland and Mexico, were rejected by the respective governments of the countries. Interest in solar radiation modification will certainly continue, but the future for the technology is uncertain. Whether the method is or is not deployed, it must not displace efforts to reduce greenhouse gas emission that lie behind the environmental crisis.

Energy from Nuclear Fusion:

Nuclear fusion is the holy grail of energy production. On December 13, 2022, the Department of Energy (DOI) announced that for the first time a controlled nuclear fusion had been achieved which produced more energy than was used to initially drive the reaction.¹³ The energy was produced by the fusion of deuterium and tritium nuclei to produce a helium nucleus, a neutron, and energy. This reaction is one of several that are the source of energy at the center of the sun.