Canada’s oil-drenched sands give it the second-largest oil reserves in the world. Using the “tar sands” pollutes air and water, destroys forests and could cause cancer. Should we leave oil sands alone?

Decay is part of life, and death. When garbage decays in a landfill, or manure decays in a tank, the result is methane. Is this natural gas a problem — or an opportunity?

Coal ash is a giant garbage problem. Should we recycle more ash into concrete? A new process might save cement, rock, and landfill space.

As New Orleans sinks and the seas rise, hurricanes are getting worse. Does it make sense to start restoring marshes and barrier islands that dampen the hurricanes? Could wetlands moderate the next Katrina?

How should we deal with mercury air pollution in air, fish and water? Why do the studies of mercury consumption not agree? What to do when the studies conflict…

As Congress, president debate changes to immigration laws, we wonder if immigration-fueled population growth is an environmental issue. Should United States reduce immigration?

An international team of scientists selected the Homestake goldmine to be the world’s deepest underground lab, but the project may sink.

Renewable energy and the hydrogen economy get a boost from new invention.

New photovoltaic (PV) cells combine polymer and inorganic semiconductors — could be cheaper to manufacture.

Worldwide thirst for oil, Hurricane Katrina, political instability, conservation failures add up to record demand and record prices for fuel. Can inherently “safe designs” reduce the risk of meltdown? Should we support a revival of fission power?