Dehydrate the stratosphere to curb global warming? Scientists float risky new strategy

Given the alarm about rising levels of carbon dioxide and methane, it’s easy to forget that plain old water vapor is a major greenhouse gas, too. It can linger for years in the stratosphere, for example, absorbing heat from the surface and re-emitting it back down. According to one study, a possible jump in stratospheric water during the 1990s may have boosted global warming by up to 30% during that time. But what if you could stop water from getting there in the first place? That’s the idea behind a new geoengineering technique, proposed today in Science Advances . 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 ...
Source: ScienceNOW - Category: Science Source Type: news