• 1997 was the warmest year on record. Global warming is now happening faster than at any time in the last 10,000 years, and the 10 warmest years on record have been experienced during the last two decades.

• Scientists agree the most likely cause is pollution of the Earth's atmosphere with greenhouse gases such as carbon dioxide from the burning of coal, oil, and gas to produce energy and fuel automobiles.

• Higher temperatures cause water volume to expand. In the case of the world’s oceans, the effects are visible in rising sea levels (10-25 centimeters, on average, this century). Sea-level rise can in turn have a negative impact on coastal erosion and flooding of low-lying areas, cause greater storm damage, make coral reefs more vulnerable, affect salinity and ecosystems in mangroves and wetlands and cause more pollution from land to drain into the ocean.

• Higher temperatures are melting glaciers and polar ice, altering arctic and Antarctic habitats and further endangering species like the polar bear, walrus, whales, coral reefs, migrating birds, nearly all forms of life, as well as adding to sea level rise.

• The Pacific Ocean west of California has warmed by 1.5 degrees Celsius, which has triggered declines of zooplankton and the disappearance of an estimated 4 million sea birds.

• The Northeast states have experienced the warmest January through June period since climate records were first kept in 1895. --ENN 7/7/98

• The Bering Glacier in Alaska has shrunk by 10-12 km in length during the last century,losing 130sq km in area

• Human activities are causing some greenhouse gases, such as carbon dioxide, to build up in the atmosphere. Whenever we burn fossil fuels (gasoline, oil, coal or natural gas), more carbon dioxide is emitted to the atmosphere. Forest destruction and agriculture also release greenhouse gases.

• Since the industrial revolution, CO2 gases emitted into the atmosphere have increased by 27%. Another greenhouse gas, methane, has more than doubled.

• If we do not act to reduce our emissions of these heat-trapping gases, it is predicted that global temperature could rise 2° to 6° F in the next 100 years. Just a few degrees' difference in the global average temperature can mean a major climate change.

Source: Annual Energy Review, 1997.

As concerns about global warming continue to mount, attention is turning again to the so-called “greenhouse effect” and the gas emissions thought to cause it. Anthropogenic, or human-caused, emissions are suspected to be the chief cause of the greenhouse effect.

Carbon Dioxide. Carbon dioxide is the largest component of human-caused emissions, accounting for 5.5 billion metric tons of gas in 1996, up from 4.7 billion metric tons in 1985. Emissions caused by the burning of fossil fuels totaled 1.5 billion metric tons in 1996. (There is one metric ton of carbon in every 3.667 metric tons of carbon dioxide gas.) Consumption of petroleum products to fuel automobiles, burning of coal to produce electricity, and use of natural gas, were the biggest sources of carbon dioxide emissions in 1996.

Methane. Energy-related activities also accounted for the largest share of methane emissions (11.6 million metric tons) in 1996. Landfills were responsible for another 10.3 million metric tons, and agricultural sources (such as digestive processes in ruminant animals like cattle, sheep and goats, and the anaerobic decomposition of organic materials in animal waste and rice paddies) emitted 8.8 million metric tons in 1996.

Nitrous Oxide. Emissions of nitrous oxide, which, molecule for molecule, has a warming potential greater than either carbon dioxide or methane, dropped to 0.4 million metric tons of gas per year after having stayed at 0.5 million from 1991 through 1995.

Pollutants. Some pollutants that harm public health such as carbon monoxide, nitrogen oxides, and nonmethane volatile organic compounds (VOCs), also influence atmospheric Concentrations of greenhouse gases. In 1995, carbon monoxide emissions fell seven percent to 92.1 million metric tons, the lowest level since 1985. Nonmethane VOC emissions fell only slightly, while emissions of nitrogen oxides declined five percent over the 11-year period, to 21.8 million metric tons in 1995.

Electric Power Generation. In 1996, electric utilities and nonutility power producers (NPPs) combined emitted 2.7 billion short tons of carbon dioxide, 13.7 million short tons of sulfur dioxide, and 9.1 million short tons of nitrogen oxides. Emissions of carbon dioxide and nitrogen oxides were 13.5 percent and 3.1 percent higher, respectively, than in 1989, the earliest year for which data for both utilities and NPPs are available. Sulfur dioxide emissions fell 17.7% over the period due primarily to greater use of lower sulfur coal and of scrubbers at electric utility coal-fired generating units.

NPPs raised their total net electric output by 27% between 1992 and 1995 at a cost of a nine percent increase in carbon dioxide emissions. Electric utilities' total net output increased seven percent during the period, while their emissions of carbon dioxide rose four percent. The ratio difference is due in part to fuel use patterns: NPPs rely on natural gas for 52% of their output and natural gas has the lowest carbon content of the fossil fuels. Electric utilities produce 54% of their output using coal, which has the highest carbon content.