(CNN)To avoid a global warming catastrophe by the end of the century, humans may need to actually hack the climate.
Whether you call it hacking, or "fiddling with the knobs in the climate system," or the less-imaginative "geoengineering," it revolves around this question: Can humans game the system by using science to reverse global warming?
One way to keep global average temperatures from warming beyond a catastrophic 2-degree-celsius tipping point, according to some experts, is to suck massive amounts of CO2 out of the atmosphere.
How would you do that?
Responding to a recent climate change story by CNN's John Sutter, Trevor Algatt of Los Angeles asked about a possible solution he heard about. "There's a new technology that can extract carbon from the air and condense into 'fibers' for use in buildings, electronics, cars, clothing and other manufactured goods," Algatt wrote. "I'm sure you guys have seen/read/heard about it — the inventors say that, if implemented on a large enough scale ... it could return our atmospheric carbon to pre-industrial levels within a decade. How legitimate is this? Is this cause for celebration? Or a cool technology that's more pipe dream than solution?"
Well, yeah. Scientists say it's theoretically possible to extract CO2 from the air and turn it into materials for buildings and clothes and other everyday stuff.
But wait, it's not quite time to put on our party hats and celebrate. There are a couple of problems that have to be solved first.
1. The process would be very expensive
2. Sucking all this CO2 out of the air creates a logistical problem: Where will we put it?
"What people don't grasp is the sheer size," said Dr. Klaus Lackner, director of Arizona State University's Center for Negative Carbon Emissions. "If you drive a car, you put out about a pound of CO2 per mile. Per person, we put out 15 tons of CO2 per year." There are limits, Lackner said, to how much CO2 we can capture and store.
Assuming that problem will be figured out eventually, Lackner and other ASU scientists are developing a machine that can pull CO2 out of thin air.
A concept design for Arizona State University's carbon scrubbing machine. (Click to expand)
A concept drawing for the machine looks like a huge box, with a big sail attached to it. Inspired by trees, these sails act as the "leaves" of ASU's machine. The sails are made of plastic resin. As air flows over the plastic resin sails, they grab CO2 and hold on to it.
CO2 binds to the plastic when the material is dry. To release the CO2 from the plastic, you have to get it wet. That's how the CO2 will be harvested from these machines -- either for immediate use, or to be put into storage. CO2 also should be captured at fossil-fuel burning power plants, Lackner said.
In Massachusetts, urban design group SHIFTBoston is waiting for Lackner to fully develop his carbon-scrubbing resin so it can be used to create "Boston Treepods" -- synthetic, solar-powered devices that would scrub CO2 and provide light at night.
An artist's rendition of CO2-scrubbing Boston Treepods.
For now, ASU's device is being developed for use in greenhouses, to feed plants. Plants need CO2 to grow. "I don't think that's solving the climate problem, but it demonstrates that the technology works," said Lackner. If it proves itself, maybe someday machines like these could be used for massive carbon dioxide farms that harvest CO2 from the air.
Some of of the CO2 could be used to make liquid fuel or building materials. Massive amounts of CO2 would have to be stored in a safe, stable environment. That's never been done before on that kind of scale.
"The simplest place to put it is at the bottom of the ocean," said Yale University geologist Donald Penman, who studies carbon fluctuations underground, in the ocean and the air. "You have to be worried about unforseen side effects. Addressing one problem by manipulating global-scale geochemical fluxes; it just sounds like you're asking for other sorts of trouble. It's fiddling with the knobs in the climate system. You might be opening Pandora's box."
Other skeptics of climate hacking worry it will needlessly lengthen human reliance on fossil fuels. Let's keep our eye on the ball, they say. Getting rid of fossil fuels and carbon emissions should be the most immediate goal. "We're at that moment when we could make change, and geoengineering gets in the way of that change," said Bill McKibben.
The widely respected National Academy of Sciences recommends more research into large-scale CO2 removal while focusing on mitigating greenhouse gas emissions.
In November and December, experts will gather at an important United Nations meeting in Paris. They'll try to work out a new agreement on climate change and how to reduce CO2 in the atmosphere. New data will be released about changes in the average global temperature.
Some experts fear if the average global temperature rises above two degreees celsius, reversing global warming will be even more challenging. Research indicates that to keep below 2 degrees celsius, the world may have to take more CO2 out of the air than we put into it. That might mean using CO2-sucking technology to hack the climate.
"It becomes one tool in a larger tool set," said Lackner. Bottom line, he said, as long as we consume fossil fuels, the carbon problem will get worse. "Either you abandon fossil fuels, or you find a way to get that carbon back."