Though geoengineering proposes a quick fix to climate issues, its potentially wide-reaching consequences make it difficult to test.

Figure 1. The caldera at the summit of Mount Pinatubo in the Philippines on August 1, 1991, less than two months after the volcano erupted in June of that year. The 1991 eruption was the second-largest eruption of a land volcano in the 20th century and released millions of tons of sulfur dioxide. (Image Credit: United States Geological Survey)

On June 15, 1991, Mount Pinatubo erupted in the Philippines, expelling 15 million tons of sulfur dioxide over 12 miles into the atmosphere. Volcanic ash blanketed the stratosphere, and some released sulfur gases reacted to form sulfuric acid, some of which clumped into aerosols. Reflecting sunlight, these fine airborne particles cooled the Earth by around one degree Fahrenheit for two years (NASA Earth Observatory, 2001).

Such pronounced effects of volcanic eruptions on global temperatures, also known as volcanic winters, led scientists to believe that dispersing particles into the sky on purpose could cool our fevered Earth. However, as is the case with many geoengineering technologies, the proposed technique raises unanswerable questions. What kinds of reflective particles should be released? How much? How do we account for dispersed effects? Evidence suggests that the 1991 eruption altered precipitation patterns and caused extreme weather conditions in areas from along the Mississippi River to the African Sahel (Self et al., 1993).

These difficult questions and indirect cause-effect relationships capture the crux of the debate over geoengineering. Should we research geoengineering techniques? Should a country be allowed to unilaterally implement such a technology?

Perhaps the one question that we can and should answer now is: why propose geoengineering technologies in the first place—isn’t our first priority to reduce carbon emissions?

However, the effects of increasing amounts of carbon dioxide in the atmosphere take years to fully manifest; even if we were to immediately stop carbon emissions, Earth’s temperature would continue to rise (Frölicher et al., 2013). We could be inevitably hurling towards a tipping point right now that would trigger a cascade of catastrophic climate events, meaning we should keep our options open in terms of exploring promising solutions. Geoengineering technologies could offer a quick—albeit temporary and highly risky—fix, in the case that we are driven to extreme action.

There are two main categories of geoengineering, removing carbon dioxide from the atmosphere, and reducing solar radiation. The first could be addressed by planting more trees, as geoengineering is broadly defined as “the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change” (Royal Society, 2009). Or we could pursue less straightforward approaches. One popularly explored idea is ocean seeding—fertilizing oceans with iron to stimulate carbon-consuming plankton growth.

In 2012, American entrepreneur Russ George dumped around 100 tons of iron sulphate into the Pacific Ocean off the west coast of Canada, violating two international moratoria, in what The Guardian called the “world’s biggest geoengineering experiment.” By framing it as a “salmon enhancement project” premised on the idea that increased plankton growth would allow the marine food web to flourish, George had convinced the indigenous Haida Nation village council to funnel $2.5 million to the Haida Salmon Restoration Corporation. In reality, he planned to turn it into a lucrative business, selling credits for the carbon dioxide removed into the ocean to companies hoping to offset the emissions they release.

While the iron sulphate triggered a plankton bloom spanning close to 4000 square miles, as revealed in satellite images, it is difficult to prove that the experiment actually reduced atmospheric carbon dioxide (Tollefson, 2012). The 13 small-scale ocean seeding experiments conducted since 1990 similarly couldn’t reach a conclusive stance toward the effectiveness of plankton fertilization (Wallace et al., 2010).

Unanticipated effects can entangle us when we fiddle with the environment. Even slight interferences could have far-reaching consequences for our ecosystems. When English landowner Thomas Austin introduced 24 European rabbits to Australia, he probably did not anticipate rabbits becoming invasive pests responsible for crop damage in the millions of dollars.

Ocean seeding could result in serious environmental side effects in not only nearby regions but also those “far removed in space and time,” from toxic algal blooms to potentially harmful shifts in ocean oxygen levels and acidification. Moreover, as plankton dies and decays, consuming oxygen, anoxic zones could suffocate important organisms and destroy ecosystems at the bottom of the ocean (Wallace et al., 2010).

The other broad geoengineering technique is albedo modification. Aside from the aforementioned dispersal of fine particles into the stratosphere to mimic the effects of a volcanic eruption, these other geoengineering technologies include cloud whitening, where vapor is added to the atmosphere to increase cloud reflectivity.

First proposed in 1999 by climatologist Jonathan Latham, marine cloud brightening (MCB) artificially blanches clouds by uniformly spraying them with fine saltwater particles from ships. The idea spawned from early satellite images containing white streaks: ship tracks, clouds formed by aerosols released by ships. If ships emitted sea spray in locations conducive to marine stratocumulus cloud formation, these clouds could be packed with fine droplets to reflect more sunlight.

Scientists have conceived ways to overcome some of the proposal’s technological hurdles, a major one being how ships could generate hundreds of gallons of ocean mist per minute. “Albedo yachts” would harness wind energy to generate the electricity needed to spew the fine seawater particles one kilometer into the atmosphere (Latham et al., 2012).

However, like other geoengineering technologies, MCB brings its share of risks. For instance, some researchers worry that if MCB were implemented in the Atlantic Ocean, less evaporation in the cooled region could reduce precipitation over the Amazon rainforest. Another concern is that cooling the Earth without addressing the root problem—carbon dioxide levels—would just reduce convection and thus rainfall, as the same amount of greenhouse gases would be in the air (Economist, 2015).

If anything, the one trend that we see is that the effects of geoengineering are inconclusive. While there is a general consensus in the scientific community that we should continue to develop these technologies as a last resort and perhaps move toward small-scale trials, many geoengineering techniques are simply too risky to implement in real life: many studies rely on computer models to predict outcomes.

While humans have been manipulating, transforming, and harnessing the environment—in a sense, geoengineering—for ages, these relatively recently proposed geoengineering techniques are different in their wide-reaching scope. What is ethically concerning about geoengineering is that it doesn’t just use the environment—it irreversibly manipulates it. Furthermore, geoengineering could be implemented unilaterally but has geographically uneven and displaced effects, blurring responsibility for unintended consequences.

Geoengineering arguably already poses a moral hazard. With even the slightest intimation that large-scale intervention could be a quick fix to climate change, people could think that we can afford to continue emitting greenhouse gases and not take daily measures to reduce our ecological footprint. After all, humans have generally been pretty good at solving the problems we have created ourselves. Chlorofluorocarbon manufacture was outlawed internationally after it was discovered to destroy the ozone layer, for instance.

But climate change likely does not have a straightforward solution, unlike what some geoengineering proponents may suggest. If we don’t act now, could we fall short this time?