Before our Global Positioning System (GPS) navigation devices can tell us where we are, the satellites that make up the GPS need to know exactly where they are. For that, they rely on a network of sites that serve as “you are here” signs planted throughout the world. The catch is, the sites don’t sit still because they’re on a planet that isn’t at rest, yet modern measurements require more and more accuracy in pinpointing where “here” is. To meet this need, NASA is helping to lead an international effort to upgrade the four systems that supply this crucial location information.

The Montreal Protocol led to a global phase-out of most substances that deplete the ozone layer, such as chlorofluorocarbons (CFCs). A happy side-effect of the gradual ban of these products is that the Earth’s climate has also benefited because CFCs are also potent greenhouse gases. However, now a “rebound effect” threatens to accelerate the rate of global warming.

Researchers report that projected increases in sea level and storm intensity brought on by climate change would make devastating storm surges — the deadly and destructive mass of water pushed inland by large storms — more frequent in low-lying coastal areas. Regions such as the New York City metropolitan area that currently experience a disastrous flood every century could instead become submerged every one or two decades.

In H.G. Wells’ classic science-fiction novel, The War of the Worlds, bacteria save Earth from destruction when the Martian invaders succumb to infections to which humans have become immune through centuries of evolution. If a team led by researchers has its way, bacteria — with a little assist from science — will help prevent global destruction for real by trapping underground a greenhouse gas, carbon dioxide, that threatens Earth’s climate.

In the first look at the overall effect of air pollution from the excavation of oil sands, also called tar sands, in Alberta, Canada, scientists used satellites to measure nitrogen dioxide and sulfur dioxide emitted from the industry.