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”[1] 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?