Week of 5/8/2005

Dear EarthTalk: What are the implications for Montana’s Glacier National Park if the glaciers there keep melting?

—Oliver Ryan, New York, NY

Indeed, the glaciers for which Glacier National Park is named are melting away due to increasing global temperatures in recent decades, attributable most likely to global warming. A century ago, Grinnell Glacier, once the park’s largest, covered almost 440 acres. Today it has shrunk to just a quarter of that size. Many of the glaciers are gone altogether: According to the Sierra Club, the number of glaciers in the park has dropped from around 150 in 1850 to approximately 35 today.

Most of the glacier loss in the park has occurred since the late 1960s when global warming trends began to intensify. Park scientists are now worried that, if nothing is done to curb global warming, by the year 2030 there may not be a single glacier left in Glacier National Park.

Glaciers form when huge ice sheets build up under snow that has slowly accumulated over time. As the snow cover mounts, the intense weight compresses the delicate snowflakes beneath the surface, gradually changing them into the ice grains that make up glaciers. During the last Ice Age some glaciers were a mile thick, covering huge swaths of the Earth, and carving out much of the topography we know today through their slow and grinding movements.

The warming of the Earth that occurred at the end of the last Ice Age—and which melted glacial ice from pole to pole—was a natural phenomenon, and took place over thousands of years. Today, the carbon dioxide emissions generated over just the last half-century from industrial and automotive sources could, say scientists, lead to an equivalent amount of glacial melting within just decades, not millennia.

This process could put plants and animals, which have adapted to certain living conditions over time, in deep trouble as their habitat characteristics shift right under their feet, fins and roots. And Glacier National Park will be no exception. For example, the lack of glaciers and snow pack there could eliminate avalanches, which perform a valuable ecosystem function by knocking down forested stands to make way for new growth in meadows. The berries that are prevalent in these meadows are a major nutrition source for the grizzly bears that call the park home. Without avalanches and the meadows they create, the park’s already stressed grizzly population could suffer drastic declines.

Beyond such ecological implications, no one knows how a glacier-less Glacier National Park might play to tourists doing their grand western tours. If visitation to the park and therefore the region were to drop significantly, the local economy—now dependent upon tourism revenue—could suffer debilitating losses. After all, who would visit a place called Glacier if there were no glaciers to see?

CONTACTS: Sierra Club, www.sierraclub.org/globalwarming/articles/glacier.asp , www.sierraclub.org/globalwarming/articles/glacier.asp; Glacier National Park, www.nps.gov/glac .

Dear EarthTalk: I’ve heard that aluminum is toxic. At the same time aluminum frames are said to be the healthiest choice for replacement windows, especially for those who are chemically sensitive. Are aluminum windows safe?

—F. Lane, San Diego, CA

Aluminum can be toxic if ingested in large amounts, but there is no evidence that it causes health problems through the kinds of minor skin or airborne exposure one might receive from a window frame. As such, aluminum window frames are certainly healthy alternatives to fiberglass or vinyl, each of which are problematic because they can "off-gas" chemicals like formaldehyde into the indoor environment of your home, which could in turn aggravate chemical sensitivities.

Homeowners should be sure that any aluminum windows they install feature "thermal breaks," a design that involves fusing two separate frames together so as not to conduct the heat that precipitates mold growth. Millions of people are allergic to mold, which can spread from window frames to the wood structure of a house and cause widespread rot.

On the downside, environmentally conscious consumers should know that the manufacture of aluminum is energy intensive and requires the burning of significant quantities of fossil fuels. Recycling your beer and soda cans can help reduce this problem because it takes far less energy to re-process aluminum than it does to produce it from scratch. Fortunately, a high percentage of aluminum is already being recycled today.

Also, John Bower, founder of the Healthy House Institute and author of several books on eco-friendly design and building, recommends putting triple glazed "low-emission" ("low-E") coated window glass in aluminum frames to preserve indoor air quality and maximize energy efficiency. "Over their lifetime, houses [with these windows] should save more energy than was consumed to process the aluminum frames in the first place," he says.

Wood window frames, as long as they are not "pressure-treated" with arsenic-laden pesticides or harvested from endangered "old-growth" forests, are also an attractive, healthy and green-friendly alternative to fiberglass or vinyl frames. But aluminum still provides more bang for the cost-conscious consumer’s buck, often costing less than half of what wood frames would set you back.

CONTACTS: The Healthy House Institute, www.hhinst.com ; Energy Star Anatomy of an Energy Efficient Window, www.energystar.gov/index.cfm?c=windows_doors.pr_anat_window.