Dear EarthTalk: How is it that dams actually hurt rivers?-- Missy Davenport, Boulder, CO
Dams are a symbol of human ingenuity and engineering prowess—controlling the flow of a wild rushing river is no small feat. But in this day and age of environmental awareness, more and more people are questioning whether generating a little hydroelectric power is worth destroying riparian ecosystems from their headwaters in the mountains to their mouths at the ocean and beyond.
A wobbling of the Earth on its axis about 20,000 years ago may have kicked off a beginning to the end of the last ice age. Glaciers in the Arctic and Greenland began to melt, which resulted in a warming of the Earth, a new study says. Above, Greenland's Russell Glacier, seen in 1990.
The last big ice age ended about 11,000 years ago, and not a moment too soon — it made a lot more of the world livable, at least for humans.
But exactly what caused the big thaw isn't clear, and new research suggests that a wobble in the Earth kicked off a complicated process that changed the whole planet.
Ice tells the history of the Earth's climate: Air bubbles in ice reveal what the atmosphere was like and what the temperature was. And scientists can read this ice, even if it's been buried for thousands of years.
This NASA map shows the size of aerosol particles in the atmosphere. Green areas indicate larger, more naturally occurring particles like dust. Red areas indicate smaller aerosol particles, which can come from fossil fuels and fires. Yellow areas indicate a mix of large and small particles.
A robotic arm breaks off a chunk of mineral-rich rock deep underwater. Nautilus Minerals of Australia hopes to develop and expand undersea mining by extracting copper, gold, silver and zinc from the seafloor.
Credit Nautilus Minerals
Credit Nautilus Minerals
This deep-sea rock is rich in copper. Minerals form in the seafloor because a natural hot spring has been laying them down for thousands of years.
Filmmaker James Cameron recently reminded us of the wonders of the sea by diving solo in a submarine to the deepest spot in the ocean. Next year, if all goes as planned, a rather different expedition will take place 1,000 miles south of that dive: An Australian company will start mining for copper, gold, silver and zinc on the seafloor off the shore of Papua New Guinea.
A wildfire in the foothills southwest of Denver continues to burn out of control. It's destroyed dozens of homes and buildings, and with two people confirmed dead and another missing, it looks to be Colorado's deadliest wildfire in decades.
A day and a half after the fire started, the weather at the command post is so beautiful it's hard to imagine the nearby blaze is raging almost out of control. Mark Techmeyer of the Jefferson County Sheriff's Department calls the Lower North Fork Wildfire a monster.
Researchers haven't given much thought to the effect of noise and noise pollution on plants. After all, plants don't have ears — at least, not the kind you hear with — so there doesn't seem to be much point. But thanks to ecologist Clinton Francis, that could be about to change.
Francis is a postdoctoral researcher at the National Evolutionary Synthesis Center in North Carolina. But he has spent the past few years in northwestern New Mexico, studying noise pollution in Rattlesnake Canyon.
A coalition of Great Bay area communities is suing the state and the Department of Environmental Services, claiming DES failed to follow proper rules when determining water quality standards in the Great Bay.
Dover, Portsmouth, Rochester, Exeter and Newmarket claim DES violated state and federal law by not conducting a formal public process when determining water quality standards in the Great Bay.
As a result, the communities say they face unnecessary multi-million dollar wastewater treatment upgrades.
In Wisconsin, a bill that would authorize a hunting and trapping season for wolves sits on Governor Scott Walker’s desk. The bill pits republican and democratic supporters against environmental and conservation groups who say the proposal has no basis is the science of wildlife management.
Shell Oil plans to explore for petroleum off Alaska's north coast this summer. The native people of Alaska have a big stake in both oil revenue and environmental protection. That conflict has played out in recent trips by Inupiats to Washington, D.C., to argue their case.
Rising gas prices have again shifted the political debate between those calling for more drilling to meet America's fossil fuel dependency and those advocating for investment in alternative energy sources. Many environmentalists are convinced that we are nearing the day when fossil fuels are tapped out, or too expensive or too harmful to extract.