2003 EARTH SCIENCE VIDEOTAPES |
| |
Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| THE CASE OF SOOT AND RECEDING ICE
| G03-069 | 12/22/03 | 00:03:31 | Black soot may contribute to melting glaciers and other ice on the planet and eventually a warmer Earth. Traveling potentially thousands of miles from its sources on air currents, this pollution eventually settles out of the air, onto land and into the oceans. On ice and snow, it darkens normally bright surfaces. Just as a white shirt keeps a person cooler in the summer than a black shirt, the vast stretches of polar ice covering much of the planet's top and bottom reflect large amounts of solar radiation falling on the planet's surface, helping regulate Earth's temperature. Soot lowers this albedo, or reflectivity, and the ice retains more heat, leading to increased melting.
|
TAPE CONTENTS: |
| ITEM (1): Bright White Reflects Light - This animation provides a close perspective of the relationship between ice and solar reflectivity. As glaciers, the polar caps, and icebergs (shown here) melt, less sunlight gets reflected into space. Instead, the oceans and land absorb the light, thus raising the overall temperature and adding energy to a vicious circle (first case). Soot-darkened ice retains more light, contributing to the process (second case). As light is absorbed, the environment is heated, thus intensifying a feedback loop: a warmer planet yields more ice melting and thus an even warmer planet.
|
| ITEM (2): Is The Ocean Rising? - The polar caps not only hold much of the planet's total fresh water but also help regulate the Earth's temperature. Soot-darkened ice has a lower albedo, or reflectivity, than clean ice, so it absorbs more light, leading to melted ice. Were the ice caps to appreciably recede, sunlight that otherwise would have been reflected back into space would get absorbed by the darker, denser mass of ocean and land beneath. The attending planetary conditions necessary to facilitate polar melting would likely have enormous effects on the environment.
Courtesy: NASA
|
| ITEM (3): Melting Snows of Kilimanjaro - Scientists see the same albedo-changing effect of soot on alpine glaciers as on polar ice caps. Some recent researcher has suggested the ice fields on Africa's highest mountain may have shrunk by 80 percent in the past century. The snow cap formed some 11,000 years ago. The Landsat satellite captured these images of Kilimanjaro February 17, 1993 and February 21, 2000.
Courtesy: NASA/USGS
|
Earth Science Gallery