By CLIVE HAMILTON
26 May 2013
CANBERRA, Australia (The New York Times) – The concentration of carbon dioxide in the earth’s atmosphere recently surpassed 400 parts per million for the first time in three million years. If you are not frightened by this fact, then you are ignoring or denying science.
Relentlessly rising greenhouse-gas emissions, and the fear that the earth might enter a climate emergency from which there would be no return, have prompted many climate scientists to conclude that we urgently need a Plan B: geoengineering.
Geoengineering — the deliberate, large-scale intervention in the climate system to counter global warming or offset some of its effects — may enable humanity to mobilize its technological power to seize control of the planet’s climate system, and regulate it in perpetuity.
But is it wise to try to play God with the climate? For all its allure, a geoengineered Plan B may lead us into an impossible morass.
While some proposals, like launching a cloud of mirrors into space to deflect some of the sun’s heat, sound like science fiction, the more serious schemes require no insurmountable technical feats. Two or three leading ones rely on technology that is readily available and could be quickly deployed.
Some approaches, like turning biomass into biochar, a charcoal whose carbon resists breakdown, and painting roofs white to increase their reflectivity and reduce air-conditioning demand, are relatively benign, but would have minimal effect on a global scale. Another prominent scheme, extracting carbon dioxide directly from the air, is harmless in itself, as long as we can find somewhere safe to bury enormous volumes of it for centuries.
But to capture from the air the amount of carbon dioxide emitted by, say, a 1,000-megawatt coal power plant, it would require air-sucking machinery about 30 feet in height and 18 miles in length, according to a study by the American Physical Society, as well as huge collection facilities and a network of equipment to transport and store the waste underground.
The idea of building a vast industrial infrastructure to offset the effects of another vast industrial infrastructure (instead of shifting to renewable energy) only highlights our unwillingness to confront the deeper causes of global warming — the power of the fossil-fuel lobby and the reluctance of wealthy consumers to make even small sacrifices.
Even so, greater anxieties arise from those geoengineering technologies designed to intervene in the functioning of the earth system as a whole. They include ocean iron fertilization and sulfate aerosol spraying, each of which now has a scientific-commercial constituency.
How confident can we be, even after research and testing, that the chosen technology will work as planned? After all, ocean fertilization — spreading iron slurry across the seas to persuade them to soak up more carbon dioxide — means changing the chemical composition and biological functioning of the oceans. In the process it will interfere with marine ecosystems and affect cloud formation in ways we barely understand.
Enveloping the earth with a layer of sulfate particles would cool the planet by regulating the amount of solar radiation reaching the earth’s surface. One group of scientists is urging its deployment over the melting Arctic now.
Plant life, already trying to adapt to a changing climate, would have to deal with reduced sunlight, the basis of photosynthesis. A solar filter made of sulfate particles may be effective at cooling the globe, but its impact on weather systems, including the Indian monsoon on which a billion people depend for their sustenance, is unclear. [more]