Hurricanes and CD jewel cases.

Did global warming cause Hurricane Katrina or make its impact worse?--John O'Dwyer, Hull, MA

NO single storm or its intensity can be attributed to climate change alone, but scientists do believe that warmer ocean temperatures as a result of global warming may be intensifying the strength of hurricanes--and therefore could have contributed to Katrina's fury. The reason is that warmer ocean temperatures, like those that occur in the tropics between June and November, cause instability in the lower atmosphere, which, in turn, "fuels" developing hurricanes.

A recent study by climatologist Kerry Emanuel of the Massachusetts Institute of Technology (MIT) concluded that tropical storms and hurricanes in both the Atlantic and Pacific Oceans have increased in duration and intensity by 50 percent since the 1970s.

The hottest years in recorded history have been over just the last 15 years, and with worldwide industrial emissions of carbon dioxide at their highest levels ever, most scientists agree that human industrial activity is a

significant culprit. "My results suggest that future warming may lead to an upward trend in [hurricanes'] destructive potential, and--taking into account an increasing coastal population--a substantial increase in hurricane-related losses in the 21st century," says MIT's Emanuel.

Beyond reigniting debate about global warming, Katrina's impact is also highlighting the consequences of the rapid destruction of wetlands throughout the United States and world. Louisiana alone has lost more than a million acres of coastal wetlands since the 1940s. Some environmental leaders maintain that the installation of the levees surrounding New Orleans a half century ago led to the decay of nearby wetlands that historically served as buffers in protecting against flooding and other storm damage.

According to the environmental organization Ducks Unlimited, one mile of marsh can reduce a storm surge by about one foot. "Theoretically," explains Tom Moorman, director of conservation planning for the group's Southern Regional Office, "if you had a healthy chunk of marsh when Katrina hit, that could have mitigated some of the damage." CONTACT: The Heat is Online, www.heatisonline.org; Kerry Emanuel, "Anthropogenic Effects on Tropical Cyclone Activity," www.wind.mit.edu/-emanuel/panthro2.htm.

Where can I recycle my plastic CD jewel cases?--Bianca Hoffman, Bridgeport, CT

Environmentalists have been worried about CD jewel case disposal ever since compact discs first became popular in the 1980s. Jewel cases are made out of polyvinyl chloride (PVC), a petrochemical-based plastic that is notoriously difficult to recycle and has been linked to elevated cancer rates among workers and neighbors where it is manufactured. Also, the lead often added to strengthen PVC can contaminate water, soil and air around PVC manufacturing sites.

Worse yet, because it contains a variety of additives and lacks a uniform composition, PVC is far less recyclable than other plastics. Its quality degrades after only two or three "cycles." Greenpeace has identified PVC as the least recycled of the six major common plastics. The U.S. Environmental Protection Agency (EPA) estimates that less than one percent of total post-consumer PVC is recovered or reprocessed.

As a result, most municipal recycling centers do not accept PVC products, meaning that millions of CD jewel cases either take up room indefinitely in landfills, where they won't biodegrade, or are incinerated. And unfortunately, the burning of PVC creates airborne dioxins.

While options for recycling CD jewel cases and other PVC plastics are limited, the Sammamish, Washington-based GreenDisk company will take jewel cases for a fee of $5.95 for up to 20 pounds. GreenDisk then turns the resulting raw materials into GreenDisk-branded office supplies including, you guessed it, CD jewel cases containing at least 76 percent post-consumer waste content.

Another way to make use of old jewel cases would be for art's sake. They can be used as picture flames or to show off collections of miniature items, such as coins, stamps or dried flowers. CONTACT: GreenDisk, (800)305-DISK, www.greendisk.com.

Send your questions about environmental issues, from the personal to the political, to EarthTalk, P.O. Box 5098, Westport, CT 06881, or e-mail [e-mail]. Include your full name, address and a daytime phone number.

Help get Earth Talk into your community by asking your local newspaper editor to visit our informational page at: www.emagazine.com/Earth Talk/Earth Talk_letter.html.