On the horizon

'Trading' pollution

A new study from the National Center for Atmospheric Research in Boulder, Colo., suggests that the US trade imbalance with China is also leading to a carbon-emissions imbalance, with America "exporting" CO2 emissions to China as it buys Chinese goods. According to the study, if the United States had produced the goods it bought from China between 1997 and 2003, US CO2 emissions would have been 6 percent higher. China's CO2 emissions would have been 14 percent lower. The researchers, whose work appears in the journal Energy Policy, trace the difference to China's heavy use of coal and fewer fuel-efficient technologies.

Paleontologists researching a new specimen of the earliest known bird, Archaeopteryx, have found its feet are more like those of certain dinosaurs than modern birds. The work adds another bit of evidence to support the still-contested case that birds descended from theropod dinosaurs similar to the Velociraptors of "Jurassic Park" fame. Archaeopteryx's feet showed that, like its theropod relatives, it could hyperextend its second toe. And unlike modern birds, the first toe is curved inward - rendering it unable to perch. This suggests to scientists, whose work is in the journal Science, that the Archaeopteryx may be a more distant relative to modern birds than they believed.

A team of scientists have discovered tiny microbes in Greenland ice cores that may have implications for the search for life on Mars. While studying gases trapped in ice segments, they found very high methane levels in several places. The cause: methane-generating microbes. The team suggests that these organisms could live under harsh conditions for millions of years. Other researchers have detected methane levels in Mars's atmosphere that they say can't be explained solely by geological sources. The team calculates that a "colony" of microbes beneath Mars's surface could generate excess methane. Their work is in the Proceedings of the National Academy of Science.