Resource: Earth's Cryosphere: Antarctica

Earth's polar regions are part of the cryosphere—the frozen areas of Earth's surface, including snow, glaciers, ice sheets, ice shelves, icebergs, sea ice, and permafrost (land that is below 0°C for two or more years). Scientists are interested in studying the cryosphere because it plays an important role in regulating Earth's climate system. For example, sea ice acts as an insulating barrier and reduces the transfer of moisture and heat from the ocean to the air, which affects atmospheric circulation. In addition, freezing and melting of sea ice affect the salinity of the water and influence ocean circulation patterns.

Snow and ice are also highly reflective and thus strongly influence Earth's radiation budget. Earth's average overall albedo (the percentage of sunlight that is reflected from the surface) is about 30 percent; in other words, Earth absorbs about 70 percent of incoming solar radiation. However, because snow and ice are much more reflective than water and land (the albedo of fresh snow is about 90 percent), they decrease the amount of energy absorbed by Earth and have a cooling effect. As a result, the amount of surface area covered by snow and ice has a significant impact on Earth's climate. Changes such as a decrease in the size of the cryosphere caused by melting can trigger a positive feedback loop and accelerate climate change. Warmer temperatures melt snow and ice, which decreases Earth's albedo, which in turn causes further warming and more melting.

Satellites play a vital role in helping scientists study the cryosphere because they gather data in remote areas where it is difficult to gather direct, hands-on measurements. Prior to satellite technology, polar scientists could only collect data in small areas and at limited time intervals. However, from their vantage point above Earth's surface, satellites can make large-scale observations of the planet at regular intervals. For instance, microwave sensors and radar systems onboard satellites can easily map Antarctica's ice cover throughout the year despite its remote location, extreme temperatures, and frequent cloud cover and darkness.

Instruments onboard satellites make measurements by detecting and recording electromagnetic radiation in a range of wavelengths, such as visible, infrared, and microwave. After the data is processed, false colors are assigned to the data to create images that help scientists visualize the information. With the wealth of information gathered by satellites, scientists hope to gain a better understanding of the polar regions and the potential consequences of changes to the cryosphere.

To learn more about the cryosphere, check out Earth's Cryosphere: The Arctic, Earth System: Ice and Global Warming, and Antarctic Ice: Sea Level Change.

To learn more about Earth as a system, check out Earth as a System and Global View of the Seasons.

To learn more about satellites, check out Satellites Orbiting Earth and Earth System: Satellites.

• Describe some of the features of the Antarctic.
• Identify some of the features that are changing in the Antarctic. What led to the collapse of the Larsen B Ice Shelf?
• How do these changes impact conditions in this region? What are the global impacts?