Dehydrate the stratosphere? Study suggests it to fix climate change. - USA TODAY

Dehydrate the stratosphere? Study suggests it to fix climate change.

Some scientists have a new idea that could help fix climate change: Dry out the sky
Doyle Rice

It may sound like the plot of an old James Bond movie, but an idea to "dehydrate the stratosphere" to slow climate change is real.

In a new study released Wednesday in Science Advances, researchers propose a controversial geoengineering strategy to reduce global warming, one that involves dehydrating the stratosphere by removing water vapor – the most abundant greenhouse gas.

Indeed, although greenhouse gases like carbon dioxide and methane are the most important drivers of human-caused climate change, water vapor remains the most common greenhouse gas. Thus, removing it from the atmosphere would help mitigate climate change, study authors say.

How would dehydrating the stratosphere work?

In the study, which was conducted by researchers from the National Oceanic and Atmospheric Administration(NOAA), scientists suggest trying what they call "intentional stratospheric dehydration."

According to study lead author Joshua Schwarz, a research physicist at NOAA’s Chemical Sciences Laboratory in Boulder, Colorado, this concept would involve seeding small particles (known as ice nuclei) into the stratosphere using high-altitude planes.

If such seeds can be introduced into the stratosphere, he said, then some of the water vapor will condense into ice and fall, thereby removing excess water vapor and dehydrating (at least partially) the stratosphere.

The study suggests this strategy could plausibly work after overcoming several technical barriers. Schwarz admits that at this time, "we don't have a plan or the technology to do this."

Will it counteract the effects of carbon dioxide (CO2)?

"No!," said Schwarz, adding that it would only cool the atmosphere 1/70th as much as CO2 is warming it. It would only be "a very small shift in the other direction."

He said that CO2 remains a huge problem in our atmosphere and that this method would only have a small impact, compared to CO2.

Some scientists are skeptical of the plan

"I have to be very skeptical," said Kevin Trenberth, a scientist at the National Center for Atmospheric Research. "Focusing on dehumidifying the stratosphere by itself makes no sense to me."

Michael Mann, a meteorologist at the University of Pennsylvania, said that "in this case, the authors concede a large number of caveats, one of the most critical being the potentially limited lifetime of the effect. Like many of the proposed inventions, it would have to be done regularly to keep up the offsetting cooling effect, and meanwhile the CO2 that is accumulating in the atmosphere is there for the long-term."

Geoengineering is controversial

The idea behind geoengineering is to manipulate some part of the Earth's systems to keep global warming under control — while also acknowledging that the ideal solution remains a reduction in the emissions of greenhouse gases.

Geoengineering technologies are still being developed, and no large-scale experiments or operations have been conducted, researchers say.

Still, it remains a controversial topic: "The ethical questions associated with climate manipulation loom so large that some forms of geoengineering are simply unacceptable," Trenberth wrote in a letter in the journal Physics Today.

Mann said, "these sorts of geoengineering gambits could easily become like climate methadone — we become reliant on doing them and if the will, or infrastructure for implementing this ever fails, than any climate benefit is lost, while the CO2 continues to accumulate."