Wizardry to some, anathema to others, geoengineering—or climate engineering—is slowly encroaching on the territory of traditional climate policy. The Intergovernmental Panel on Climate Change’s (IPCC) next Assessment Report, due in 2013/14, will cover “the deliberate large-scale manipulation of the planetary environment” as a potential strategy to counteract man-made climate change. Technological solutions are increasingly seen as a necessary complementary strategy to mitigation and adaptation to contain the worst impacts of climate change. They may well be risky; but if the global transition to a low-carbon economy comes too late and we therefore face an increase in global average temperatures by 4 degrees Celsius by the end of the century, technology could potentially be the proverbial last straw. The attitude toward geoengineering differs considerably among scientists and climate policymakers in the U.S. and Germany, and this article will demonstrate why this is the case. It first explains the main approaches to geoengineering as well as their respective risks and then discusses the perceptions of geoengineering in the U.S. and Germany, respectively. Finally, the article explains the need for an international research agenda on geoengineering.
What is Geoengineering?
Geoengineering is not new. It was first mentioned in a 1965 report entitled “Restoring the Quality of Our Environment,” which was prepared for then-president Lyndon Johnson. Yet it was not until forty-five years later that geoengineering gained further attention. Over the past two years or so the possible failure of international climate negotiations and increasing evidence for an acceleration of climate change have alarmed many in the international climate science and climate policy communities. Geoengineering is therefore now increasingly being looked into as a kind of “insurance policy” should “conventional” climate policy fail.
Today, there are two broad approaches to geoengineering. The first is a manipulation of global temperatures through direct interference with the earth’s radiation balance. This is known as Solar Radiation Management (SRM). If we can reduce the amount of solar radiation hitting the earth, the ensuing cooling effect would alleviate some of the impacts of climate change. One way of bringing about such an effect could be the artificial brightening of clouds over the oceans. Solar radiation can also be manipulated by dispersing sulphur particles in the stratosphere at a height of 15 to 50 kilometers, for instance with the help of airplanes. These particles or aerosols would then block parts of the sunlight and prevent it from reaching the earth. The effects are much like those of a volcanic eruption: when the Pinatubo in the Philippines erupted in 1991, global temperatures decreased by about 0.5°C for one year due to the sulfur dioxide in the atmosphere. So why not bring about the same effect in an artificial manner?
An alternative approach to geoengineering, Carbon Dioxide Removal (CDR), consists of an interference with the earth’s carbon cycle. Since surplus CO₂ is one of the biggest culprits of climate change, extracting CO₂ from the atmosphere and sequestrating it in geological formations or on the ocean floor could help contain some of the worst consequences. Some of the approaches to CDR that are being discussed at the moment are outright uncontroversial. They comprise reforestation and afforestation or improved land-use management to enhance the ability of soil to store carbon dioxide. Another, more contentious, method is the fertilization of oceans with iron to stimulate the growth of algae. The objective is for the algae to absorb CO₂ and sequestrate it deep in the ocean when they die. Whether or not it is possible to store CO₂ indefinitely has not been determined yet, though.
In principle, both geoengineering approaches sound logical at first glance. And to a small group of experts in the international climate research community, such as Ken Caldeira at Stanford or David Keith at Harvard, they have significant appeal. Yet the great majority of scientists and policymakers warn against geoengineering or consider it as outright crazy because of the risks involved. Proponents argue, however, that it might soon be necessary to balance the risks of climate change against the risks of geoengineering as an instrument of last resort should the global transition to a low-carbon economy come too late. This does not mean that geoengineering should at any point in time replace ambitious policies to reduce greenhouse gas (GHG) emissions. After all, a de-carbonization of the economy has additional benefits such as the creation of new jobs and markets in the cleantech and renewables sectors, increased food, water, and energy security, and hence more global stability. Nevertheless, the risk of tipping points in the global climate system justifies the in-depth study of geoengineering technologies. Once a certain threshold of CO₂ and other GHG in the atmosphere is reached, tipping elements can be triggered that make climate change an irreversible process. Among these tipping elements are—as remote as they might still seem—the melting of the Greenland ice sheet and Arctic sea ice loss.