EarthTalk: What Exactly is the 'Greenhouse Effect'?

Dear EarthTalk: What exactly is the "greenhouse effect" and how is it a bad thing?
-- Suanne Gladstone, Queensland, Australia

The "greenhouse effect" occurs naturally when heat from the sun enters our atmosphere but cannot escape because it is blocked by water vapor, carbon dioxide and other airborne elements, thereby causing a warming of the Earth. Without a natural greenhouse effect, the average temperature of the Earth would be about zero degrees Fahrenheit instead of its present 57 degrees Fahrenheit.

But increasing amounts of pollutants from manufacturing and power plants, agricultural activities, automobiles and other sources that burn fossil fuels have led to an excessive build-up in the Earths atmosphere of greenhouse gases such as carbon dioxide, nitrous oxides and methane. Scientists believe that this build-up is exaggerating the naturally occurring greenhouse effect and is to blame for the average temperature on Earth rising by more than one degree over the last century.

The International Panel on Climate Change, an international group of climatologists, predicts that Earths temperature will continue to rise from two to 10 degrees Fahrenheit during this century as a result of human industrial activity. According to the Sierra Club, the likely effects of this global warming include the melting of massive icebergs and glaciers, sea level rise, accelerated coastal erosion, more (and more severe) hurricanes, the spread of infectious diseases and widespread species extinctions, among other problems.

To address this crisis, 127 countries have agreed on mandatory curbs on greenhouse gas emissions via an international treaty set to go into effect in 2005 called the Kyoto Protocol. The treaty is so-named because it was the outcome of a meeting held in Kyoto, Japan in 1997. Under the Protocol, the United States is supposed to cut its greenhouse gas emissions by seven percent by the period between 2008 and 2012. With four percent of the worlds population, the U.S. currently accounts for about 25 percent of the Earths greenhouse gas emissions. The U.S., however, has refused to sign this United Nations-backed agreement, arguing that U.S.compliance with the terms of the treaty would harm the American economy.

But, according to the Natural Resources Defense Council (NRDC), some of the U.S. governments own studies should quell such fears: While industry trade associations have published many misleading claims of economic harm, says NRDC, two comprehensive government analyses have shown that it is possible to reduce greenhouse pollution to levels called for in the Kyoto agreement without harming the U.S. economy.

Instead, the U.S. is pushing for technological approaches that would remove carbon dioxide from the atmosphere and store it below ground or under water. But environmentalists fear that loading massive mounts of carbon dioxide into the Earth and oceans could wreak ecological havoc in other ways, and doubt that human-induced global warming can be solved by American ingenuity alone.

Dear EarthTalk: What is the impact of the skiing industry on our environment?
-- Elizabeth Marley, San Bernardino, CA

While skiing affords millions of enthusiasts the opportunity to enjoy the great outdoors during the winter, its impact on the environment is fairly substantial. The creation and ongoing expansion of ski resorts leads to the development of otherwise unspoiled alpine ecosystems and often destroys vital wildlife habitat. Ski resorts also use substantial amounts of water for snowmaking and other activities, and generate significant carbon dioxide pollution from energy used to run lifts and visitor facilities.

For instance, Colorados famed Aspen Mountain ski resort churns through 45 million gallons of water each year to make snow in the winter, irrigate the landscape in the summer, and to provide for the personal needs of staff and visitors year round. Sprawling guest accommodations, not to mention the construction of new trails and runs, have kept the endangered Canada lynx -- as well as myriad other alpine fish and wildlife species -- on the run and teetering on the brink of extinction. Meanwhile, the resorts mechanical facilities and related services emit 76 pounds of carbon dioxide per skier each year. Despite these statistics, Aspen is still considered to be among the more environmentally responsible ski resorts.

In light of such problems as well as increased pressure from environmental advocates, many ski resorts in recent years have started to focus on lightening the impact of their operations. More than 170 ski resorts -- representing about 60 percent of U.S. skier destinations -- have signed onto the National Ski Areas Associations environmental charter, which calls for responsible management of resources, decreased energy use and limits on development. While adherence to the charters tenets is voluntary, its adoption by a majority of the countrys leading ski resorts is a step in the right direction.

Meanwhile, the non-profit Ski Area Citizens Coalition (SACC) publishes an annual Ski Area Environmental Scorecard which rates hundreds of U.S. ski resorts on the basis of environmentally sound management practices, especially individual resorts efforts to maintain ski terrain and service facilities within existing boundaries so as to maximize the preservation of undisturbed lands. SACCs criteria also include the protection of wetlands, old growth forest, unique geological formations and roadless areas. SACC also takes into account energy and water consumption habits. Some Colorado ski resorts that received high marks in that regard include Aspen, Buttermilk and Wolf Creek

Meanwhile, a handful of forward-thinking operations -- including Mt. Hood Meadows, Cooper Spur and Mount Bachelor in Oregon, Deer Valley and Park City in Utah, and Lake Tahoes Northstar in California -- allow skiers to add a few extra dollars onto their lift ticket prices to purchase wind energy which then increases the amount of clean energy that goes into the grid that powers the operations.

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