Montana Earth Science Picture of the Week

The photos of Grinnell Glacier illustrate the toll that global warming has taken on the glaciers in Glacier National Park. Of the 150 glaciers that were present in 1850, only 35 remain today. According to a team of U.S.G.S. scientists, the glaciers will melted completely within 30 years. The same tend has been observed throughout the world. The snows of Mount Kilamanjaro are disappearing, as are the Himalayan glaciers. Experts fear that glaciers in the Andes and the Swiss Alps will suffer the same fate within decades. There is no longer any debate among scientists that the world is getting warmer. Nor is there much doubt that the current rate of warming is faster than any other time over the past 10,000 years. In fact, eight of the ten hottest years have occurred since 1990.

What’s causing this “global warming”?
Most climate scientists think that the burning of fossil fuels (coal, oil, natural gas) has contributed to the warming trend. Whenever we burn coal to generate electricity, burn natural gas to heat our homes and water, or burn gasoline to run our trains, planes, and automobiles, carbon dioxide is released into the atmosphere. Carbon dioxide is a “greenhouse gas”. Like car windows on a sunny day, carbon dioxide lets sunlight pass through. Light rays that strikes dark surfaces are absorbed and changed into heat. Then, as this heat is given off as infrared waves, both the glass in the car and the carbon dioxide in our atmosphere absorb these longer waves, “trapping” the heat. Although not everyone agrees with this theory, the vast majority of scientists do believe that an increased “greenhouse effect” is at least partly responsible for the global warming.

Term: greenhouse effect

Sources:

1. Associated Press, “Major Meltdown”, The Independent Record (Helena), November 24, 2002.

2. Patrick Judge, Energy Policy Director for the Montana Environmental Information Center