2003 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| SEASONS OF CHANGE: EVIDENCE OF ARCTIC WARMING GROWS | G03-056 | 10/24/03 | 00:11:21 | Experts have long regarded Earth's polar regions as early indicators for global climate change. But until the last few years, wide ranging, comprehensive research about overall polar conditions has been challenging to conduct. Now a more than twenty-year record of space based measurements has been analyzed by researchers at NASA's Goddard Space Flight Center. Based on their findings, evidence of a warming planet continues to grow.
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TAPE CONTENTS: |
| ITEM (1): Arctic Changes Reporter Package - There's more to shrinking polar caps than simply less ice. A new twenty year study being released by NASA researchers suggests that average temperatures in The Arctic are not only getting warmer, but also staying warm for more days throughout the year. As a result, polar ice is thinning faster than ever and its geographic boundaries are retreating--both signs of powerful climate change.
SOT Dr. Josefino Comiso, Senior Scientist, NASA
The perennial ice cover has been retreating at a very rapid rate of almost 10 percent per decade. If that's sustained we may get to loose multi-year ice within the century.
Shrinking amounts of ice worldwide not only means there's a potential for rising sea levels, but also it increases the potential for accelerating rates of change. That's because a smaller polar cap means less surface area can reflect solar energy hitting the Earth. Lower reflectivity means higher levels of warming, and that means even faster loss of ice.
The implications could be dramatic. Changes in polar ice can affect ocean chemistry, circulation patterns in the atmosphere and oceans, worldwide weather systems and more.
The polar regions are Earth's thermostat. Those thick blankets of ice help regulate the Earth's overall temperature. According to this new study, that delicate equilibrium may be shifting. Space agency experts say that only with more research will accurate predictions be possible about the long-term health of the planet.
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| ITEM (2): Changing Seasons, Changing Ice - Using data collected by a number of satellites from 1979 to 2003, we see in this sequence how scientists have been able to stitch together a careful record of sea ice in The Arctic. In 2002 scientists recorded the lowest concentration of sea ice ever. While temperature changes vary across the vast expanse of The Arctic, overall trends suggest that decreasing ice concentrations are due to a significant increase in ocean warming, from rising surface temperatures to the total number of annual "melt days".
Courtesy: NASA
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| ITEM (3): 1979 to 2003 Sea Ice Comparison - These two images show a comparison of Arctic sea ice concentrations between 1979 and 2003. 1979 marks the first year that data of this kind became available in any meaningful form. To date, 2003 is the second lowest concentration of sea ice on record. Experts recorded the lowest measured concentration of sea ice during 2002.
Courtesy: NASA
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| ITEM (4): Warmer and Cooler - Space based observation facilitate a kind of thoroughness that ground based observations cannot realistically approach. Based on 20 years of data collected by infrared measurements, surface warming trends in The Arctic are eight times greater than trends over the past 100 years, suggesting a rapid acceleration in warming. According to this study, the sea ice melt season has increased by 10 to 17 days per decade. The readings are not uniform, however. While average temperatures are increasing throughout The Arctic, there are several places where there appear to be cooling trends. Greenland is a good example; the data there suggest a mild decrease in average temperatures through the time period being analyzed. The data used to create these images were collected by the AVHRR instruments onboard the NOAA POES satellites.
Courtesy: NASA
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| ITEM (5): Pressure to Change - Taken in isolation, one year's worth of data does not tell us much. Just as we all know that some days of the year might be unusually hot or cold, we intuitively understand that dramatic events in isolation are simply anomalies. But many samples of data can imply change. Taken as collections of information, trends begin to emerge based on a pattern. In this sequence we see how 21 years of accumulated data indicate temperature trends in the Arctic. While the overall direction of the trend suggests warming for the region, there are many places where the average temperature is falling year over year.
Courtesy: NASA
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| ITEM (6): Bright White Reflects Light--The Global Role of The Polar Caps - The polar caps not only hold much of the planet's total fresh water, but also play an important role in regulating the Earth's temperature. The relevant characteristic is called albedo. It's a measure of how much radiation, or light, is reflected from a body. Similar to how a white shirt helps keep 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. 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. As light is absorbed, the environment is heated, thus intensifying a feedback loop: a warmer planet yields more ice melting thus an even warmer planet.
Courtesy: NASA
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| ITEM (7): Is The Ocean Rising? - This animation provides a closer perspective of the relationship between ice and solar reflectivity. As glaciers, the polar caps, and in this case, icebergs melt, less sunlight gets reflected into space. It is instead absorbed into the oceans and land, thus raising the overall temperature, and adding energy to a vicious circle. The attending planetary conditions necessary to facilitate polar melting would likely have enormous effects on the environment. These include the likely melting of ice sheets covering Greenland and the vast reaches blanketing the southern polar cap. As the ice over Greenland and Antarctica is NOT floating, a corresponding rise in the world's sea level would almost certainly result if that ice melted.
Courtesy: NASA
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| ITEM (8): Observations From Above--NASA's Earth Observing Fleet - From space, the whole world unfolds every day. Orbiting the planet more than ten times a day, NASA's Earth Observing Fleet is uniquely able to make the kinds of measurements that experts need to track systemic changes on the Earth below. With advanced vehicles like Terra, Aqua, ICESat, and more, researchers now have the tools to monitor the Earth's overall health to a degree never before possible.
Courtesy: NASA
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| ITEM (9): Selected Soundbites With Dr. Josefino Comiso, Senior Scientist, NASA and Dr. Waleed Abdalati, Cryospheric Sciences Program Manager, NASA
Courtesy: NASA
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Earth Science Gallery