As kids spend more times indoors, experts wonder what is being lost. Do humans need nature?

Just after humans reached the Western Hemisphere, many large mammals went extinct. Some scientists have blamed hyper-effective human hunting. But a new study fingers changes in climate and environment.

Is global warming feeding hurricanes? Global warming has already raised sea levels. Is warming also making hurricanes like Katrina more intense? Some new evidence says yes.

As the administration allows more snowmobiles to buzz through Yellowstone, scientists cry foul. Are the parks more than playgrounds?m Scientists call for more money for basic research, but the Bush administration favors recreation.

Feeling burned? Farmed salmon have higher levels of a brominated flame retardant than wild salmon.

Evidence from ice cores in Greenland and Antarctica show how fast the climate has changed in the past. In this era of global warming, you can’t count on a slow, gradual, predictable warming.

Endangered species profiles: Mexican wolf, Houston Toad, Sumatran Rhino, Mountain Gorilla, Mountain mist frog, red-crowned cranes, Delhi Sands flower-loving fly, beluga sturgeon, Higgins’ eye pearly mussel, West Indian manatee, piping plover, Higgins’ eye pearly mussel

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…

History shows societies collapse without soil. What can the world cando to keep our dirt clean?

In a wilderness, roads can interrupt migration corridors; kill wildlife through vehicle impacts, block movement of surface water; compact soil, harming burrowing animals and changing groundwater flow; cause air pollution and traffic noise; and allow invasive species to enter.