the Editors of E - The Environmental Magazine

Dear EarthTalk: I've heard that nanoparticles are already in consumer products, yet have we really studied their potential health impacts?
-- Dan Zeff, San Francisco, CA

Nanotechnology makes use of minuscule objects -- 10,000 times narrower than a human hair -- known as nanoparticles. Upwards of 600 products on store shelves today contain them, including transparent sunscreen, lipsticks, anti-aging creams, and even food products.

Dear EarthTalk: I keep meeting people who say that human-induced global warming is only theory, that just as many scientists doubt it as believe it. Can you settle the score? -- J. Proctor, London, UK

So-called "global warming skeptics" are indeed getting more vocal than ever, and banding together to show their solidarity against the scientific consensus that has concluded that global warming is caused by emissions from human activities.

Upwards of 800 skeptics (most of whom are not scientists) took part in the second annual International Conference on Climate Change -- sponsored by the Heartland Institute, a conservative think tank -- in March 2009.

Dear EarthTalk: What are some of the leading proposed technological fixes for staving off global warming, and how feasible are they? -- James Harris, Columbus, Ohio

While most of the world fixates on how to reduce the amount of carbon dioxide (CO₂) and other greenhouse gases we emit into the atmosphere, scientists and engineers around the world are busy working on various "geo-engineering" technologies -- many of which are highly theoretical -- to mitigate global warming and its effects. Many scientists oppose using new technology to fix problems created by old technology, but others view it as a quick and relatively inexpensive way to solve humankind's most vexing environmental problem.

Dear EarthTalk: I'm a musician and am curious about what the guitar industry is doing to ensure that the wood it uses is not destroying forests. -- Chris Wiedemann, Ronkonkoma, NY

Though it has not received a lot of press to date, the industry is on the case -- in part for the sake of its own survival, and thanks to the hard work of a handful of green groups, guitar makers and wood suppliers.

Dear EarthTalk: What is the so-called "smart grid" I've been hearing about, and how can it save energy and money? -- Larry Burger, Litchfield, CT

America's electricity grid is built upon what many consider to be an antiquated principle: Make large amounts of electricity and have it always available to end users whether they need it or not. It's much like the way most home water heaters keep water constantly hot even when it is not being used. It is also a strictly one-way relationship, with utilities supplying power to end users, but not vice-versa.

Dear EarthTalk: Could it really be true that a single large volcanic eruption launches more greenhouse gases into the atmosphere than the amount generated by all of humanity over history? -- Steve Schlemmer, London, England

This argument that human-caused carbon emissions are merely a drop in the bucket compared to greenhouse gases generated by volcanoes has been making its way around the rumor mill for years. And while it may sound plausible, the science just doesn't back it up.

Dear EarthTalk: With all the talk of rising seas, what could happen to the rivers that flow into the oceans? Will they reverse flow? Will rising seas back up into fresh water lakes? And what happens to our groundwater should saltwater flow backwards into it? -- Sandy Smith, concerned Michigander

Dear EarthTalk: I want to convince my high school to go green. What would it cost for a school to switch to all recycled paper products and all energy-efficient lighting? -- Danel Berman, via e-mail

Dear EarthTalk: With all the talk of desalinization of ocean water for drinking, what do we know about the impacts this might have on climate, ocean salinity and other natural processes? -- Fred Kuepper, via e-mail

Dear EarthTalk: How can I determine if it is more eco-friendly to fly or drive somewhere? -- Christine Matthews, Washington, DC