When Humans Design Climate

Last week an article appeared in Forbes magazine bearing the title “As Humans Fumble Climate Challenge, Interest Grows in Geoengineering.” The article reports that during an appearance at Carnegie Mellon University, Dr. David Keith, one of North America’s foremost advocates for research into geoengineering, observed that in recent months serious discussion of geoengineering “really is happening in a way that it wasn’t happening before.”

Geoengineering (also known as “climate engineering”) is defined as the large-scale and deliberate intervention into the climate system in order to counter global warming. The various technologies proposed to achieve this goal range from the decidedly untechnical idea of simply planting millions more trees to the rather more sophisticated plan of placing mirrors in space to reflect back sunlight.

IMG_0976Two different strategies have traditionally been lumped together under the banner of climate engineering. The first is to capture carbon from the air and either to use this carbon to create liquid hydrocarbon fuels OR to pipe the extracted carbon somewhere it can be stored safely (probably underground). This first class of approaches is called Carbon Dioxide Removal.

The second class of approaches is known as Solar Radiation Management (or Sunlight Reflection Methods). This group of technologies works by making portions of the earth’s surface, or different parts of the atmosphere, more reflective to incoming sunlight. If you can cause just a small portion of the short-wave energy coming our way from the sun to bounce back into space before it starts warming the land, the oceans, or the atmosphere, you can cause a notable reduction in global temperatures.

Since the Paris agreement of 2015, the idea of capturing carbon out of the air has become much more part of the mainstream. With carbon dioxide concentrations already hovering somewhere north of 405 parts per million, removing atmospheric carbon has become virtually a necessity. The last time CO2 concentrations were this high was more than three and a half million years ago in an epoch known as the Pliocene. Back then, sea levels may have been 70 feet (22 meters) higher than today and arctic regions were home to five different types of pine trees. It is questionable whether it is helpful any longer to stigmatize carbon dioxide removal with the label of geoengineering. If you think of CO2 as a harmful pollutant, then any attempt to remove it from the place where it is doing harm seems like a piece of sound, common sense.

Solar radiation management, on the other hand, remains a dramatic intervention into the earth system. A thousand years ago, King Cnut the Great of Denmark sat his throne on the beach, looked out at the North Sea, and ordered the tides to turn back. Solar radiation management is an effort to do what Cnut failed to do, but this time usurping a natural process with its origins embedded even deeper in the solar system. Unlike Cnut’s effort to control the tides, when it comes to turning back sunlight, we have evidence we can do it.

Every big volcanic eruption that has occurred since record keeping began has had measurable effects on global climate. Tambora in 1815, Krakatoa in 1883, El Chichón in 1982, and Mount Pinatubo in 1991 all put enough material in the stratosphere to bounce a meaningful portion of incoming sunlight back into space for a couple of years. In each case, the climate responded. Mary Shelley is said to have written Frankenstein after being kept indoors all summer by unusually cold weather in Switzerland a year after Tambora. In the eighteen-eighties, Edvard Munch was inspired to paint The Scream after witnessing iridescent red sunsets in Norway following Krakatoa’s explosive outburst half a world away. As these epic eruptions showed, stopping sunlight does not require mirrors.  You can do it with dust and droplets of the right liquid.

It is an unfortunate fact that the agent scientists think most suitable to create the desired effect is sulphuric acid. Delivered to the stratosphere by balloon and hose or fleets of airplanes, sulphuric acid droplets would swiftly be dispersed around the world by cold stratospheric winds and form a hazy reflective barrier to incoming solar rays.

As you can imagine, the idea of spraying sulphuric acid into the stratosphere is not without controversy. When David Keith appeared on The Colbert Report to explain the concept, Colbert roasted him mercilessly. Ethicists have also swarmed the academic airwaves to vent their horror. (I know because I have been one of them). But as last week’s Forbes article shows, Keith’s idea to use solar radiation management to “shave the top off the curve” of rising temperatures while a low-carbon economy is developed is inching its way towards respectability in climate policy circles.

Trying to weigh up the imminent harms of climate change against the possible side-effects of climate engineering is a complicated business. The ethical, political, and scientific puzzles cut in so many different directions that it is hard to pencil out a reliable answers about right or wrong. It is helpful, however, to step back for a second and to think of the big picture.

Humans use their brains and their hands to manipulate things. It is part of who we are as a species. Homo faber, the tool-making hominid, stands out amongst earth’s species for our extraordinary ability to create technologies to make our lives more livable.

All of this technology, however, is deployed against the background of a world that presents us with certain long-standing challenges. It is because winters are cold that we heat our homes. It is because crops are seasonal that we have learned how to preserve and store our food. Those background challenges take different forms and come at us with different intensities at different times. But they are always there, there in such a way that the nineteenth century English philosopher John Stuart Mill referred to this natural background as a “cradle of our thoughts and aspirations.”

A technology like solar radiation management is global to an unprecedented degree. It takes this background and manipulates it in such a way that the background itself becomes the tool we build or the object we manipulate. Climate engineering attempts to “make climate” in the same way that we make refrigerators or make iPhones. It goes without saying that there are risks involved in attempting to make something as complex as a planet’s climate. But even without these very real risks of harm, the philosophical turn involved in changing an ever-present background into just one more thing we manipulate marks the crossing of an historic and uncomfortable line.

Former U.S. Vice-President Al Gore has called climate engineering “delusional.” The author of the Forbes article notes that it might be just as delusional to think we can avoid the severe impacts of climate change with greenhouse gas reductions alone.

I don’t pretend to know whether the risks of climate engineering outweigh the risks of the changes to climate that are already in the pipeline. I do have the sense, however, that some elements of our natural background were not meant to become our tools.


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