A study published in Science Advances involves the ambitious and contentious idea of seeding the upper atmosphere with particles to prevent water vapor from entering in the stratosphere.

Water vapor is important because it's the most abundant greenhouse gas on Earth. The greenhouse effect occurs when gases in the atmosphere trap heat from the sun, keeping the planet livable. Water vapor is made up of complex molecules that absorb heat radiated from the Earth's surface and re-radiate it back to the planet.

Water vapor is constantly cycling through the atmosphere, evaporating from the Earth's surface, condensing into clouds, being blown by the wind, and then falling back to the Earth as rain or snow.

Researchers, led by Shuka Schwarz of the National Oceanic and Atmospheric Administration (NOAA), argue that water vapor in the stratosphere plays a critical role in trapping heat from the Earth's surface.

Science.org reported:

By targeting rising, moist air and seeding it with cloud-forming particles right before it crosses into the stratosphere, geoengineers could cool the world with an intervention far more delicate than other schemes. Drying the stratosphere might take as little as 2 kilograms of material a week, says Shuka Schwarz, the study's lead author and a research physicist at the Chemical Sciences Lab of the National Oceanic and Atmospheric Administration (NOAA). "That's an amount of material that helps open the mind to imagine a whole bunch of possibilities."

"Intentional stratospheric dehydration," as it's called, could only cool the climate moderately, offsetting roughly 1.4% of the warming caused by increased carbon dioxide over the past few hundred years. But for geoengineers who have talked about cooling the planet by loading the stratosphere with thousands of tons of reflective particles, "it's clearly a new idea," says Ulrike Lohmann, an atmospheric physicist at ETH Zürich. "This is something that could work."