Climate Engineering Could Reframe the Dialogue on Climate Change

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New study explores the potential benefits, risks, and legal challenges of solar climate engineering.

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Policymakers seeking to combat climate change often encourage consumers and businesses to take individual measures to reduce emissions. Use less electricity. Drive a smart car instead of a gas-guzzler. Recycle everything from plastic to electronics.

However, some experts are proposing an alternative solution for mitigating the effects of climate change: climate engineering. Climate engineering involves deliberate, large-scale interventions in Earth’s climate systems to reduce global warming, but its innovative approach also entails some risk. In a recent paper, Jesse Reynolds, a postdoctoral researcher at Tilburg University, explores the potential benefits, risks, and legal challenges of one solution that focuses on reducing global temperatures without curbing greenhouse gas emissions­: solar climate engineering.

Solar climate engineering, Reynolds notes, would “slightly increase the planet’s reflectivity in order to counter climate change.” Two technologies, in particular, hold the most promise, according to Reynolds. First, injecting aerosols into the upper atmosphere would mimic the cooling effect produced by volcanic eruptions, which dispel particles into the air that reflect sunlight away from Earth, thereby reducing global temperatures. Second, marine cloud brightening–the process of increasing the reflectivity of clouds over the ocean–could also cool the planet by increasing the amount of sunlight that clouds reflect back into space.

Reynolds notes that the potential benefits and risks of solar climate engineering remain unclear. Although techniques such as aerosol injection and marine cloud brightening would, according to current studies, be low-cost and technically feasible methods of rapidly cooling global temperatures, solar climate engineering remains risky.

Climate engineering implemented by different countries without coordination could create cross-border impacts and conflicts, as certain techniques, such as stratospheric aerosol injection, would necessarily be global in nature, because it is impossible to limit atmospheric particles to national boundaries. Mustering support for new climate engineering projects could also detract from existing efforts at reducing emissions. More fundamentally, climate engineering could produce unforeseen and potentially disastrous environmental risks. For instance, as Reynolds observes, although proponents of aerosol injection have identified sulphur dioxide as one candidate for injection into the stratosphere, sulphur dioxide is “expected to contribute to the destruction of stratospheric ozone.” Destroying stratospheric ozone could damage the ozone layer, which protects Earth from harmful solar radiation.

In light of the massive potential benefits and risks posed by solar climate engineering, Reynolds argues that the current patchwork of transnational policies offers “inadequate regulation.” Though a number of existing international laws, such as the United Nations Framework Convention on Climate Change, the Convention on Biological Diversity, and other relevant treaties could apply to solar climate engineering, no treaty currently exists that specifically addresses its unique transnational regulatory challenges.

Solar climate engineering is challenging to regulate on multiple levels, Reynolds notes. First, it may be difficult to implement a distinct regulation for climate engineering when it overlaps with and becomes indistinguishable from broader research on climate change. For instance, a recent experiment in which researchers injected particles into the atmosphere in order to monitor their impact on clouds could be considered a precursor to large-scale solar climate engineering, but was purportedly motivated by general research interests in climate change.

Additionally, no definitive marker exists for when a research activity becomes large enough to be regulated as climate engineering. Researchers sensitive to these concerns, according to Reynolds, have asked hypothetically whether an experiment measuring the reflectivity of a residential driveway painted white would count as a “field test” of solar climate engineering, and thus be subject to regulation.

Although Reynolds focuses on international regulation of climate engineering rather than on particular case studies of national regulation, he observes that national regulation may have significant advantages over international regulation in this area, such as better enforcement through domestic institutions and greater adaptability to risks and impacts. However, national regulation may not be sufficient to address the cross-border risks of some climate engineering.

Ultimately, despite the potential benefits of large-scale climate intervention, one thing is clear: climate engineering is no panacea. The National Academy of Sciences, a nongovernmental institution that advises the U.S. government on issues of science and technology, notes that, although climate engineering could potentially reduce global temperatures without the kinds of long-term sacrifices required by large scale reductions in carbon emissions, such an effort would only mask the symptoms of climate change without addressing its root causes. As a result, climate engineering would have no effect on other important consequences of climate change—such as ocean acidification—which are caused not by increased global temperature, but by the increased concentration of carbon dioxide in the atmosphere.

Although solar climate engineering remains a controversial issue in the debate on climate change mitigation, Reynolds remarks that its prospect alone “forces us to reconsider the actual goals of climate policy, and environment law more generally,” by critically examining the idea that emissions reduction is a means to fight climate change rather than an end in and of itself.

This revitalized dialogue, Reynolds notes, is a “welcome development.”

Reynolds’ paper is published as a chapter in The Oxford Handbook on the Law and Regulation of Technology.