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. Keynote speaker and Massachusetts Institute of Technology meteorologist Richard Lindzen told the gathering that "there is no substantive basis for predictions of sizeable global warming due to observed increases in minor greenhouse gases such as carbon dioxide, methane and chlorofluorocarbons."

Most skeptics attribute global warming - few if any doubt any longer that the warming itself is occurring, given the worldwide rise in surface temperature - to natural cycles, not emissions from power plants, automobiles and other human activity. "The observational evidence... suggests that any warming from the growth of greenhouse gases is likely to be minor, difficult to detect above the natural fluctuations of the climate, and therefore inconsequential," says atmospheric physicist Fred Singer, an outspoken global warming skeptic and founder of the advocacy-oriented Science and Environmental Policy Project.

But green leaders maintain that even if some warming is consistent with millennial cycles, something is triggering the current change. According to the nonprofit Environmental Defense, some possible (natural) explanations include increased output from the sun, increased absorption of the sun's heat due to a change in the Earth's reflectivity, or a change in the internal climate system that transfers heat to the atmosphere.

But scientists have not been able to validate any such reasons for the current warming trend, despite exhaustive efforts. And a raft of recent peer reviewed studies - many which take advantage of new satellite data - back up the claim that it is emissions from tailpipes, smokestacks (and now factory farmed food animals, which release methane) that are causing potentially irreparable damage to the environment.

To wit, the U.S. National Academy of Sciences declared in 2005 that "greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise," adding that "the scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action." Other leading U.S. scientific bodies, including the American Meteorological Society, the American Association for the Advancement of Science and the American Geophysical Union have issued concurring statements - placing the blame squarely on humans' shoulders.

Also, the Intergovernmental Panel on Climate Change (IPCC), a group of 600 leading climate scientists from 40 nations, says it is "very likely" (more than a 90 percent chance) that humans are causing a global temperature change that will reach between 3.2 and 7.2 degrees Fahrenheit by the end of this century.

CONTACTS: Heartland Institute; Science and Environmental Policy Project; U.S. National Academy of Sciences; IPCC.

DEAR EARTHTALK: Is there really such a thing as "sun-protective clothing?" If so, does it mean I can dispense with oily sunscreens once and for all?
- John Sugarman, San Diego, CA

WHILE THERE WILL ALWAYS BE A PLACE for high-quality sunscreen on body parts exposed to the sun, covering up elsewhere - ideally with clothing designed to absorb or shield the sun's damaging ultraviolet (UV) radiation - can minimize a person's skin cancer risk significantly.

With recent news about the inadequacy of many sunscreens - the nonprofit Environmental Working Group found that four out of five name brand sunscreens offer inadequate protection from the sun or contain potentially carcinogenic ingredients - covering up instead of smearing is looking better and better to many people. A handful of clothing manufacturers are responding to the increased demand for shirts, pants, dresses and hats bearing "SPF" (sun protection factor) ratings with stylish sun-protective duds.

The granddaddy of them all just might be Sun Precautions Inc., which was started 15 years ago by avid downhill ski racer and outdoors enthusiast Shaun Hughes after he was diagnosed with skin cancer at age 26. The company's Solumbra line of sun-protective casual and outdoors clothing blocks upwards of 97 percent of all UVA and UVB radiation it encounters, and is recommended by thousands of dermatologists.

To test that its product line offers the kind of protection the company advertises, Sun Precautions subjects all of its Solumbra clothing to 500 laundry cycles, then snips out fabric samples which are exposed to the equivalent of 500 days of UV rays. If the samples pass muster, the line can be shipped.

Another leader in the fast growing field is Coolibar, which boasts a 50+ SPF rating for all of its garments. Its clothing, including wide-brimmed hats and long-sleeved bathing suits among many other items, is crafted from a proprietary tight-weave yet breezy fabric it calls Suntect. Another top purveyor is Sun Protective Clothing, which makes its casual and sporting clothes from a proprietary fabric blend called Solarweave, which fends off UVA and UVB rays yet maintains a light cottony "summerweight" feel.

Some hardcore environmentalists shun sun-protective clothing because it is usually made from polyester, Lycra or nylon - all which are petroleum-derived and are can contain some nasty chemicals. But Marta Phillips of SunGrubbies.com feels that it is better to wear the clothes than to smear chemicals directly onto your skin via sunscreen. That's why her company sells a wide variety of sun-protective pants, jackets and hats, as well as specialty items such as cover-ups, sun gloves, sun sleeves and nose scarves.

If getting a whole new wardrobe of sun-protective clothing is out of the question, washing your existing clothes with Rit's SunGuard, a product that treats fabric with a compound that imparts 96 percent UV protection through about 20 washings, might be the way to go. Also, sun lovers shouldn't forget about protecting their eyes. A good pair of 100 percent UV protection sunglasses doesn't cost an arm and a leg anymore; everyone in your family needs a pair.

CONTACTS: Environmental Working Group; Coolibar; Sun Precautions; Sun Protective Clothing; SunGrubbies.com; SunGuard.

DEAR EARTHTALK: We will need to replace our house gutters soon. What are our best options from an environmental perspective?
- Jodie Green, Dallas, TX

FIRST, UNDERSTAND CLEARLY why your gutters need to be replaced. Are they rusted or broken? Are the fasteners no longer holding them in place? Or have the gutters leaked and failed to keep water out of your house? Answers to these questions will help you decide which type of gutter to choose.

Use a material that is the most durable for your climate; ultimately the longer your gutters last, the less environmental cost there will be in the product lifecycle, from manufacturing to recycling. A cheaper product that degrades twice as fast as another would not be the best choice, even if it does have a greener production process: The extra cost of having to fix your water-damaged home - and the health problems that could arise from exposure to mold - would make a "cheaper" gutter in reality much more costly.

"Galvanized steel, copper and aluminum are preferred gutter materials," reports Austin Energy, the Texas capitol's community-owned electric utility. Copper is a more expensive, high-end gutter material, as are stainless steel and wood, although wood is used mostly in historical restoration.

According to home improvement expert Don Vandervort, who writes for ThisOldHouse.com, steel and aluminum each have big pluses. Steel is sturdy, while aluminum will not rust. Copper and stainless steel are sturdy and lasting, too, says Vandervort, but they can cost three to four times as much as steel or aluminum. "Steel gutters can stand up to ladders and fallen branches better than aluminum," he says. "But even thick galvanized steel eventually rusts." He advises buying "the thickest you can afford." Austin Energy says that gutters should be a minimum of 26 gauge galvanized steel or 0.025 inch aluminum.

Polyvinyl chloride (PVC) is also used for gutters, but "can get brittle with age or in extreme cold," says Vandervort, and cannot carry as much snow load as metal gutters. PVC is also not a very green-friendly choice. The Center for Health, Environment and Justice (CHEJ) calls PVC plastic "one of the most hazardous consumer products ever created... dangerous to human health and the environment throughout its entire life cycle." When produced or burned, says CHEJ, PVC plastic releases dioxins, a group of potent synthetic chemicals that can cause cancer and harm the immune and reproductive systems.

Replacing your gutters can be an unfortunate expense, but it can provide an environmental opportunity, because the way you handle your roof's water is important. Consider linking your gutters to a "rooftop catchment system" that captures rainwater in a cistern or rain barrels and can then be used to water non-edible plantings. Efficient water use is a guideline in the U.S. Green Building Council's LEED (Leadership in Energy and Environmental Design) for Homes standard for certifying green-built homes.

Finally, if you have a problem with debris, consider a RainTube. This recycled-plastic gutter insert (which won the 2008 Sustainable Product Award from Green Building Pages) keeps gutters clear of debris, preventing overflow into your house. Of course, cleaning your gutters now and then is probably the best environmental option in that it may head off any need for replacement or modification.

CONTACTS: Austin Energy; U.S. Green Building Council; RainTube; Green Building Pages.

© the Editors of E/The Environmental Magazine, 2009

GOT AN ENVIRONMENTAL QUESTION?
Send it to: EarthTalk, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881;
submit it at: www.emagazine.com/earthtalk/thisweek/,
or e-mail: earthtalk@emagazine.com.

Read the column archives at: www.emagazine.com/earthtalk/archives.php.

ABOUT THE AUTHOR

Now in its 19th year, E/The Environmental Magazine is a bimonthly "clearinghouse" of information, news and resources for people concerned about the environment who want to know "What can I do?" to make a difference. A 13-time Independent Press Awards winner and nominee, E is chock full of everything environmental - from recycling to rainforests, and from the global village to our own backyards.

Published bimonthly by a staff of six full-time and two part-time employees (plus a steady stream of college interns), E reaches a national audience in a smartly designed full-color format, printed on recycled paper. Published by the nonprofit (501-c-3) Earth Action Network, Inc., E is independent of any membership organization and has no agenda to promote except that of our very diverse and dynamic movement as a whole.

In direct fulfillment of E's editorial mission, EarthTalk is an effort to reach "beyond the choir" of committed environmentalists and offer highly useful information to sympathetic but uninformed people shown in poll after poll to be ready and even eager for "green" information.