Wild Ideas for Stopping Climate Change Written 10 January 2017

Panelists: Moderator Marty Bradley, technical fellow, Boeing; Martin Bunzl, philosophy professor, Rutgers University; Timothy C. Langenkamp, partner, Sidley Austin LLP; Douglas MacMartin, research professor, Caltech, and senior research associate, Cornell University

by Ben IannottaAerospace America Editor-in-Chief


Participants discuss "Geoengineering to Mitigate Climate Change — Is There a Role for Aerospace," Jan. 10 at the 2017 AIAA SciTech Forum, in Grapevine, Texas.

If humanity wants to get serious about stopping human-caused climate change, it's going to have to actively intervene in the functioning of the atmosphere, said panelists Jan. 10 at the 2017 AIAA SciTech Forum in Grapevine, Texas.

Exactly how is the question. Perhaps sulfur dioxide could be dispersed in the stratosphere to reflect solar radiation. Or carbon dioxide could be captured from the air on a vast scale. Or maybe giant sunshades could be erected in space to cool Earth.

Such geoengineering might sound extreme, but according to some scientists, active intervention is going to be the only way to stave off a planetary warming of more than 1.5 to 2 degree Celsius, the threshold beyond which increases in sea level could be severe.

"It is a controversial topic," said Marty Bradley, a technical fellow at Boeing and the session moderator for "Geoengineering to Mitigate Climate Change — Is There a Role for Aerospace?"

Douglas MacMartin, a geoengineering theorist at Caltech, showed the audience a graph to make his case that adopting renewable energy and improving efficiency would not be enough to stop profound climate change.

In fact, he said it's a "pipe dream" to think that cutting carbon emission can by itself solve the problem. He cautioned that we may already have crossed a threshold to meters of sea level rise.

Striking a similar note, Martin Bunzl, a philosophy professor at Rutgers University, said the Paris climate accord is "woefully inadequate" to keep warming to 1.5 to 2 degrees Celsius. Bunzl lauded former Vice President Al Gore's passion for the topic of climate change, but he said it's simply not going to possible to turn around the energy economy over a span of just 20 years.

As MacMartin put it: "Unmitigated climate change may scare us more than risks of geoengineering."

So what exactly are the possibilities for intervention?

MacMartin said it would be possible to cool the planet rapidly, perhaps over the course of few years, by "dumping crap" in the stratosphere in what's called solar geoengineering or sometimes solar radiation management. The idea would be to mimic the effect of the 1991 eruption of Mount Pinatubo in the Philippines, which spewed tons of sulfur dioxide into the stratosphere and cooled the planet by half a degree Celsius.

MacMartin cautioned against jumping quickly to solar geoengineering, because it could have consequences that scientists do not yet understand.

"If you wanted to do it intelligently, that's probably at least decades away," he cautioned. "We need to ramp up research funding from our current level of, with a rounding error, zero," he added.

In Bunzl's view, "it's inevitable that geoengineering has to be part of the portfolio of response."

Of course, there are options other than solar radiation management. One idea is to capture carbon dioxide from the atmosphere. Questions persist about how that could be done at the required scale.

Nevertheless, Timothy C. Langenkamp, a Houston-based lawyer who helps companies raise capital for oil and gas initiatives, predicted that his industry would be interested in this technology. He said a test plant could be built to show how synthetic fuels could be derived from atmospheric carbon dioxide.

The carbon would not be sequestered, but "at least you're not adding to the problem" by drilling more fossil fuels, he said. The industry likes the idea because, if feasible, it comes with a built-in "repeatable revenue stream."

Another idea would be to orbit sunshades, perhaps made of Kapton polymer like that of the sunshield of the James Webb Space Telescope. The challenge would be getting adequate surface area into orbit. MacMartin calculates this idea would require 270 Delta 4 rocket launches every day for the next 50 years.


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