Letting the air out of the hydrogen balloon

Atmospheric scientists are trying to figure out how Earth's atmosphere would be affected by leaked hydrogen from cars, hydrogen gas stations. Some claim the "hydrogen economy" could still contribute to climate change.

"A 2004 National Academy of Sciences report on "The Hydrogen Economy" was prepared by "economists and engineers, remarkably lacking any atmospheric scientist or biogeochemists who understand the natural (atmospheric) cycle of H2," said Prather, a professor of Earth system science and former editor-in- chief of Geophysical Research Letters. "It is surprising that all of these groups examining a hydrogen economy are secure in the belief that H2 is a pure fuel, safe and harmless to the environment," although studies suggest otherwise.

One problem is that hydrogen leaked into the atmosphere binds with oxygen molecules, forming water vapor and clouds. A change in cloud abundance in some regions might alter the local temperature and climate -- for example, the climate might warm if the clouds trap heat like blankets, or the climate might cool if they reflect sunlight back into space."