Whether storing water for the future or conserving it in the present, cities across the United States are beginning to reconsider their water management practices.

Elemental mercury enters the atmosphere via multiple sources, from volcanoes to forest fires to power plants. From there, rain washes it into waterways and wetlands — where it can enter the food chain. But a new study shows that sunlight can help remove significant amounts of mercury from wetlands.

Climatologist Michael Mann met the press today at the American Geophysical Union's fall meeting to answer questions about "Climategate" and what those hacked emails really said about climate science.

Scientists spied a water-rich planet 2.7 times larger than Earth — a so-called "super-Earth" — in orbit around a red dwarf star only 40 light-years from Earth. The planet, like previously discovered CoRoT 7b, isn't habitable — but it is close enough for scientists to better study its atmosphere.

Love it or hate it, Twitter has its uses. USGS is taking advantage of the social networking site's real-time information transfer, turning barrages of tweets posted during an earthquake event into citizen science.

Is the developed world outsourcing its carbon dioxide emissions? And if so — should we help pay for them?

Energy, climate change mitigation and healthcare reform grabbed most of the U.S. policy headlines in 2009. But a few other policy gems  — for example, human spaceflight, renewable energy projects on public lands, mining reform and natural hazards — have started coalescing in Congress. EARTH contributor Corina Cerovski-Darriau outlines some of the less high-profile topics we can expect to see debated in 2010.

NASA isn't just looking out into space — many of their future endeavors will be close to home. EARTH contributor Kathryn Hansen explores the agency's upcoming and ongoing efforts to study how Earth is changing, and what the consequences of those changes will be for life on our planet. 

When it comes to natural hazards, the big issue is not in their prediction, but in mitigation — in preventing an ensuing catastrophe, such as the devastation that followed 2005's Hurricane Katrina or the 2004 Sumatra earthquake and tsunami. That's where geoscientists can truly help society reduce risk, argues EARTH contributor Mary Lou Zoback in this comment.

EARTH associate editor Erin Wayman highlights how the economic slowdown, declining construction and fewer car sales reduced the demand for raw materials and changed the commodities scene in 2009. 

The biggest change in tomorrow's agriculture will be one of mindset: It must become an industry closely connected to energy, environment, health, global security and economic prosperity, says EARTH regular contributor George A. Seielstad in this comment.

With the future of energy so uncertain, only a fool would boldly make predictions, according to EARTH regular contributor Michael E. Webber. So here, he gives his "fool's take" on the future of energy.

For our end-of-year issue, EARTH asked several of its regular contributors to look into their crystal balls and anticipate what will happen in the future in their various fields. In this comment, Rasoul Sorkhabi gives his take on the energy scenario for 2010, both in the United States and around the world.

A new suite of studies of a hominid fossil that pre-dates Lucy by more than a million years is challenging some thinking about the human family tree — and suggest that the last common ancestor of chimpanzees and humans was not very chimp-like at all.