CLIMATE

The Cure That Could Be Worse Than The Disease

Is Tinkering with Our Planet the Way to Solve Climate Change?

What if curing the planet’s climate ills were as easy as simply scrubbing the offending greenhouse gases from our atmosphere? Or what if we could build giant space mirrors to block some of the incoming solar radiation and provide some much-needed cooling? While few seriously believe that such schemes could actually put the brakes on climate change, a growing number of distinguished scientists, including a prominent Nobel Laureate, are giving voice to these controversial mitigation strategies, known collectively as geoengineering.

With international efforts to reach consensus on a successor to the Kyoto Protocol stalled, many scientists are arguing that drastic measures will be needed to prevent the worst excesses of climate change.

Geoengineering is loosely defined as the intentional large-scale manipulation of the environment in order to blunt man-made climate change.^[1] Once derided as little more than a mere distraction from the serious business of climate mitigation, the idea that humans may need to “tweak” the planet to avert a major catastrophe has gained currency in recent years. This shift in thinking has been spurred in part by the unprecedented nature of recent environmental shifts, such as the melting of the Arctic ice caps and the rapid acidification of the world’s oceans. These events, in addition to other clear instances of climate change, have cast into doubt even scientists’ most pessimistic scenarios. And while there remains a solid contingent of scientists who vehemently oppose geoengineering on scientific and ethical grounds, there is some indication that the tide may slowly be turning in favor of its advocates. With international efforts to reach consensus on a successor to the Kyoto Protocol stalled, many scientists are arguing that drastic measures will be needed to prevent the worst excesses of climate change.

The term geoengineering, as we know it today, was originally coined in the early 1970s by Cesare Marchetti, an Italian physicist, who used it to describe the injection of carbon dioxide into the deep ocean as a potential scheme for climate change mitigation.^[2] At the time, the U.S. had already discovered cloud seeding, a form of weather modification which increases precipitation by injecting chemicals such as silver iodide or dry ice into clouds, and was hastily stepping up its research into weather and climate modification to counter the Soviet Union’s dominanant position in the field at the time. Over the ensuing years, the practice of cloud seeding would fall out of favor, soon to be replaced with a newfound focus on the relationship between CO2 and climate change. The first government reports to seriously consider geoengineering as a potential countervailing measure were issued by the National Academy of Sciences in 1983 and 1992. The four options examined in the 1992 report were: reforestation, ocean fertilization, albedo modification, and the removal of atmospheric chlorofluorocarbons. Two of these—ocean fertilization and albedo modification—are at the center of the current debate over geoengineering.

Albedo refers to an object or surface’s ability to reflect solar radiation and is expressed as a value between zero and one; a colored surface with an albedo of 0.45, for example, would reflect 45 percent of the sunlight that falls upon it. Albedo modification schemes therefore intend to offset the warming effect of higher greenhouse gas concentrations by increasing the planet’s albedo. The most famous (some might say infamous), and well-studied, scheme consists of pumping sulfur dioxide into the stratosphere to reflect a slice of incoming solar radiation. Sometimes referred to as “sunshade” geoengineering, it is most commonly associated with Ken Caldeira, a scientist at Stanford University’s Carnegie Institution, and Lowell Wood (sometimes dubbed Dr. Evil), formerly of the Lawrence Livermore National Laboratory. Paul Crutzen, a 1995 Chemistry Nobel Laureate best known for his work on ozone depletion, lent his imprimatur to the scheme by publishing an essay in 2006 arguing in its favor.^[3] Caldeira and Wood believe injecting a million tons of sulfur dioxide into the stratosphere would reflect one to three percent of the sun’s rays—enough to counteract the warming impacts of climate change. The sulfur dioxide would be carried up to the stratosphere by a fleet of converted 747s, military fighters, or even large balloons. They estimate such a plan would cost roughly $1 billion a year.

The blooms, when they die off, release most of the carbon back to the atmosphere, thus causing no permanent reduction in atmospheric emissions.

The idea for ocean iron fertilization arose from John Martin, a renowned oceanographer who drew national attention for his pioneering work on the “iron hypothesis” when he jokingly told an audience at the Woods Hole Oceanographic Institution, “Give me a half tanker of iron, and I will give you an ice age.” According to this controversial theory, large blooms of unicellular, plant-like phytoplankton could be stimulated in certain parts of the ocean, called high-nutrient, low-chlorophyll zones, or HNLCs, by dumping relatively small quantities of iron dust into the water. Martin believed the blooms would be able to absorb enough atmospheric carbon dioxide so as to slow and even partially reverse climate change. This theory hinged on the notion, now widely debated, that the absorbed carbon would sink to the bottom of the ocean when the blooms eventually collapsed—thus sequestering it.

The evidence obtained from the 12 fertilization experiments carried out since his pronouncement has largely been inconclusive, due in part to the fact that most have operated under less than ideal conditions or have been too short.^[4] Initial results do seem to suggest that the sequestration effect is only temporary—that the blooms, when they die off, release most of the carbon back to the atmosphere, thus causing no permanent reduction in atmospheric emissions. Despite the uncertainty, Climos, a San Francisco-based startup, sees an opportunity to make money selling carbon credits by organizing large-scale iron fertilization expeditions. Dan Whaley, the company’s CEO, insists Climos will not begin to sell carbon credits until the evidence is there and has pledged to work with the scientific community and international bodies to ensure its efforts abide by regulatory standards.

Whether any of these schemes proves to have staying power remains to be seen. Several recent studies have demonstrated that the risks of albedo modification could far outweigh the potential benefits. Reducing the amount of sunlight reaching the planet could slash global precipitation levels, possibly leading to more droughts. Another study explicitly linked sulfur injection to a depletion of the ozone layer. Simone Tilmes, the lead author, found that it would severely weaken the ozone layer for several decades and delay the recovery of the ozone hole by up to 70 years. In late May, close to 200 countries attending a United Nations conference voted to place a moratorium on the practice of ocean fertilization, potentially putting Climos’s future plans at risk. The decision will now be referred to the London Convention, a subset of the International Maritime Organization charged with regulating the disposal of wastes at sea, which is expected to deliberate on the issue within the coming months.

In the end, whether or not we decide to pursue geoengineering will boil down to a single question: How far are we willing to push our fragile planet in order to avert the looming climate crisis?

Jeremy Jacquot is a graduate student in marine environmental biology at the University of Southern California and is the Los Angeles correspondent for TreeHugger.com.

Notes

[1] Keith, D. W. 2000. “Geoengineering the climate: History and prospect,” Annu. Rev. Energy Environ., 25: 245-284.

[2] Ibid.

[3] Crutzen, P. 2006. “Albedo enhancement by stratospheric sulfur injections: A contribution to resolve a policy dilemma?” Climactic Change, 77: 211 – 219.

[4] Boyd, P. W. et al. 2007. “Mesoscale iron enrichment experiments,” 1993-2005: Synthesis and future directions, Science, 315: 612 – 617.

Tags: Climate Change, oceans

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