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The perils of solar radiation management

[Continued from the article of the same title in the March issue]

Solar Radiation Management (SRM) affects the planet unequally. Positive affects could occur in one geographic area and negative affects in another.

In 2008, Alan Robock, a prominent critic of solar geoengineering and his colleagues published a study in the journal Geophysical Research that used a comprehensive atmospheric-ocean circulation model to simulate the effects an injection of sulfur dioxide (SO2) into the atmosphere. It found that continuously injecting sulfur dioxide into the lower atmosphere would produce global cooling. Tropical sulfur dioxide injections would produce sustained cooling over most of the world, with more cooling over continents. Arctic SO2 injection would not just cool the Arctic. Both tropical and Arctic SO2 injections would disrupt the Asian and African summer monsoons, reducing the food supply for billions of people. The study concluded that these regional anomalies are but one of many reasons that argue against the implementation of solar geoengineering.

Computer simulations since then have come to similar conclusions. They show that SRM, through a reduction in total solar irradiance by approximately 2%, roughly compensates for global mean temperature changes from a doubling of carbon dioxide concentrations. Water cycling slows down under SRM, including decreases in global mean precipitation and evapotranspiration. (Katie Dagon and Daniel Schrag (2016.)

Where the sulfate particles are injected is crucial. The National Center for Atmospheric Research (NCAR) and Cornell University has used sophisticated computer models to explore the impacts of injecting sulfur dioxide at different latitudes and altitudes. Sulfates injected at the equator affect Earth unevenly: over-cooling the tropics and under-cooling the poles. They found that cooling spread more evenly over the globe from injection sites on either side of the equator. When solar geoengineering was implemented in the Northern Hemisphere it led to a reduced precipitation in the Sahel region. In contrast, injections in the Southern Hemisphere resulted in increased precipitation in the Sahel. These changes are mainly attributed to a shift in the location of the June-October Inter-Tropical Convergence Zone (ITCZ) away from the hemisphere in which geoengineering is implemented. However, when comparable solar reduction is imposed in both Northern and Southern Hemisphere high latitudes the position of the ITCZ is nearly unaltered.

Kravatz et al. (2016) showed that annual mean Arctic temperature and the ITCZ location can be adjusted by reducing solar radiation in both the Arctic and Antarctic by appropriate amounts. “We are still a long way from understanding all the interactions in the climate system that could be triggered by geoengineering, which means we don’t yet understand the full range of possible side effects,” said NCAR scientist Simone Tilmes. “But climate change also poses risks. Continuing research into geoengineering is critical to assess benefits and side effects.”

Is It Possible To Govern Solar Geoengineering?

 “The big risks of this technology fundamentally aren’t technical,” says David Keith, “They’re political. They’re the risk of how it gets used in a divided world. How do we set the thermostat in a world where we have many different countries and many different interests and it’s really cheap to adjust the thermostat? In my view, all the really scary outcomes from geoengineering come when some country wants a climate one way and other countries want it another way. And they essentially fight over that.”

The fact that solar geoengineering could cool one part of the planet, while causing drought in another has alarmed the leaders of poor countries that already suffer the brunt of climate change drought, floods and cyclones. At the 2013 Warsaw Climate Summit shortly after Typhoon Haiyan devastated the Philippines, killing 6,300 people, Mary Ann Lucille Sering, climate change secretary for the Philippines, spoke. “Every time we attend this conference,” she said, “I’m beginning to feel like we are negotiating on who is to live and who is to die.” Naomi Klein has a similar assessment; “If geoengineering has anything going for it,” she says, “it is that it slots perfectly into our most hackneyed cultural narrative. It’s the one that tells us that, at the very last minute, some of us (the ones that matter) are going to be saved.”

Is it possible to govern solar geoengineering? Even if an international agreement could be reached, it would be very difficult to enforce it. If a rogue government began seeding the stratosphere, it could be impossible to trace the origin of the reflective particles with enough precision to punish the perpetrators. Nevertheless, serious efforts are being made to envision international governance for SRM, either through scientific consensus or through treaties between existing governments. All of the proposed governing schemes stress inclusiveness, transparency and democratic decision-making. The Solar Radiation Management Governance Initiative (SRMGI) an NGO driven organization, has already co-sponsored workshops in African countries, island nations and other developing countries to inform and involve Southern Hemisphere scientists and leaders in the decision-making process, even though everyone intuits that the important decisions about the fate of our planet will be made in the rich and powerful Northern Hemisphere.

In twenty, thirty or forty years, the perils of solar radiation management will be weighed against the actual devastation wrought by climate change. If the West Antarctic Ice Sheet is breaking up, sea level is threatening to obliterate the major cities of the world, and melting permafrost has reached a point where feed-back loops may take global warming beyond human control, SRM may look very different.

Will SRM ever be deployed? Some scientists agree with David Roberts, well-known climate journalist, that “albedo modification is a techno-besotted fantasy with an exactly zero percent chance of ever being seriously implemented. There is no Plan B. Pretending we have some other option, some other way out, some way of avoiding the difficult work ahead, does no one any good.” But Gernot Wagner, co-director at the Harvard solar-geoengineering program, believes, “It’s not a question of if, it’s a question of when someone will pull the trigger.”

The Harvard University Solar Radiation Management (SRM) Project

 David Keith and Frank Keutsch are the scientists who launched the Harvard University Solar Radiation Management (SRM) project in March of this year. The initial phase of the $20 million project is funded by Harvard, Bill Gates (a major contributor), the Hewlett Foundation, and the Alfred P. Sloan foundation. As early as 2018, they hope to spray particles of water and aluminum oxide into the stratosphere from a high-altitude balloon over Tucson. The initial experiments will be small, designed to test the delivery system, discover what kind of particles are the most effective at reflecting sunlight, how the particles clump or disperse, whether they will disrupt the ozone layer, and how they interact with other atmospheric gases. The scientists are working with a Tucson, Arizona balloon company to engineer the balloon and equip it with sensors.

In 2014, David Keith estimated that the total cost of large scale solar geoengineering would be about one billion dollars a year and the cost of geoengineering the entire planet for a decade would be less than $6 billion. It is cheap, far cheaper than the cost of cutting carbon emissions. It is inexpensive enough, that a small country, or even a rogue billionaire could finance it. In contrast, other climate geoengineering projects, such as carbon capture and sequestration (CCS) and biomass energy carbon capture and storage (BECCS), will require decades of research before they become operational, will take many more decades to have an effect on cumulative CO2 levels and will be tremendously expensive.

SRM Does Not Halt Climate Change

Keith acknowledges that solar radiation management does not stop the fossil fuel emissions that are causing climate change; it does not reduce the cumulative greenhouse gases that are warming our planet; and it does nothing to stop ocean acidification. It merely throws a veil between the earth and the sun, temporarily deflecting enough sunlight to cool the planet. He is careful to emphasize that we would still need a crash program to complete the necessary transition from fossil fuels to renewable energy. He describes SRM as a temporary “stopgap” measure, designed to give the world’s governments more time to transition to renewable energy.

Bourtai Hargrove is a climate activist, a socialist and a grandmother writing from Olympia.


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