Spotlight lecturer explains greenhouse,
"whitehouse" effect

Asst. News Editor

Dr. Stephen E. Schwartz delivered last Thursday's Spotlight lecture on atmospheric gases, aerosols and the global climate. Schwartz, an atmospheric chemist from Brookhaven National Laboratory, focused on the current study of the greenhouse effect.

"As citizens, we need to make decisions that will affect the physical health of the planet," said Schwartz. The speech focused on the energy transfer in the earth's atmosphere and described how greenhouse gases, such as carbon dioxide, methane, nitrous oxide, CFCs and HCFCs have helped trap energy from the sun and energy radiated out from earth.

Schwartz described the process of the sun adding energy to the earth, heating up the atmosphere and ground, and then radiating it back out as low-intensity infrared energy. "The infrared energy gets trapped by clouds and the energy is reflected within the earth's atmosphere," Schwartz explained.

Increasing carbon dioxide levels in air have been discovered through intense surveys of air trapped in the porous snow in glaciers, Schwartz explained. Additionally, data collected between 1958 and 1988 showed that carbon dioxide levels in the atmosphere have increased from 315 to 350 parts per million.

Trends show that worldwide average annual temperatures have been on the rise since the 1800s, increasing by one-half degree Celsius. "By contrast, the glacial period of the earth's history had only a 4-5 degree change... The change of even one degree Celsius can have drastic effects on the earth's health," Schwartz said.

Schwartz also limits the increase of aerosols in the earth's atmosphere with annual temperatures, a phenomenon Schwartz called the "whitehouse effect. Just as aerosols restrict urban areas, they also reflect radiation which would otherwise be reaching, or leaving the earth. The actual effect of aerosols is one aspect of Schwartz's research.

"The greenhouse effect is real... Greenhouse gases have been increasing,...and the global average temperature has increased. [While] the temperature of this planet has been fluctuating since the beginning of time, it is still a concern," Schwartz stated. "There are many no-regrets options, such as using less petroleum, designing more energy-efficient buildings, and relaxing dress codes so you do not have to keep the AC so high." While Schwartz warned that there are no problem-free solutions to our energy needs, he cited conservation as one place to start.

Josh Morris `96 felt that Schwartz "went through a lot of material in the time he had available and did a good job of putting together all the relevant information."

From Colby College Web Server

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