The famous mathematician John von Neumann called climate engineering a “thoroughly ‘abnormal’ industry,” arguing that large-scale interventions, including solar radiation management, were not necessarily rational undertakings and could have “rather fantastic effects” on a scale difficult to imagine. Tinkering with the Earth’s heat budget or the atmosphere’s general circulation, he said, “will merge each nation’s affairs with those of every other, more thoroughly than the threat of a nuclear or any other war may already have done”—and possibly leading to “forms of climatic warfare as yet unimagined.”

Almost four decades later, Yale economist William Nordhaus used geoengineering scenarios in his dynamic integrated climate economy (DICE) model to calculate the balance between economic growth (or decline) and climate change, as part of a 1992 National Academy of Sciences study on the policy implications of greenhouse warming. Calling geoengineering a hypothetical technology that could “provide costless mitigation of climate change,” Nordhaus came to the controversial conclusion that geoengineering produces major benefits, whereas emissions stabilization and climate stabilization are projected to be worse than inaction. He believes that geoengineering is, at present, “the only economically competitive technology to offset global warming.”

Bjørn Lomborg, trained in political theory and notorious for attempting “to redirect global priorities away from current environmental concerns,” downplayed climate change in his first book, The Skeptical Environmentalist. He has now changed his tone, admitting in a Globe and Mail op-ed that “global warming means more people will die from the heat”—and advocating the apparent cost-effectiveness of planetary climate engineering. In his op-ed, he presents dichotomous choices that are not mutually exclusive: Shall we plant trees? Cut emissions? Adapt? Or “focus on a technological solution to warming?”

Isn’t it more reasonable to pursue the first three strategies simultaneously, with new energy technologies and efficiencies? As MIT atmospheric scientist Ron Prinn said, “How can you engineer a system whose behavior you don’t understand?”

Lomborg’s article cites an un-refereed economic analysis by Eric Bickel and Lee Lane that reaches the same conclusion as Nordhaus did in 1992 by tinkering with his DICE model. Climate modeler Alan Robock calls their work “a biased economic analysis of geoengineering,” and warns that solar radiation management would cause increased damage to the stratospheric ozone layer and may in fact shut down the Indian monsoon. Any reduction in the sun’s direct radiation will cripple solar power generators and turn the blue sky milky white, even on a “clear” day. Since this type of geoengineering would also block starlight, it would mark the end of ground-based astronomy and the end of stargazing as we know it; only the brightest stars would remain visible in the night sky.

The “tiny investment” in climate engineering Lomborg is advocating as an alternative to carbon emission reductions means the oceans would continue to acidify by absorbing carbon dioxide. I don’t have enough space to critique the plan to create a post-modern El Niño with 1,900 robotic ships in the Pacific Ocean spraying sea-water mist.

In the 1830s the meteorologist James Espy was laughed out of Congress for proposing a $1:$2,000 cost/benefit ratio for making “artificial volcanoes” to enhance rainfall. He wanted to set fire to the Eastern deciduous forests, but he had not taken into account the indirect costs. Neither has Lomborg or his economists.

At a recent National Academy of Science meeting on geoengineering, planetary scientist Brian Toon told the audience that we don’t have the technology to engineer the planet. I added that we don’t have the wisdom either. Global climate engineering is untested and untestable, and dangerous beyond belief.