Page 595 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

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(a) Note the 10°C isotherm in midsummer, which designates the Arctic region, dominated by pack ice.
(b) Arctic sea ice about 965 km from the North Pole.
CRITICALthinking 17.2
A Sample of Life at the Polar Station
read some of the posts at www.snowbetweenmytoes .blogspot.com/ regarding life at the amundsen–Scott South Pole Station, antarctica. More updates, links to blogs, and South Pole news are at www.southpolestation .com/. Of the approximately 50 people who winter over at the station (between the last airplane’s departure in mid-February to the next scheduled flight arrival in mid- October), many serve as scientists, technicians, and support staff. What are some of the unique aspects of “Life as a Polie”? What do you see as the positives and negatives of living and working there? How would you combat the elements, the isolation, and the dark conditions? •
albedo, with impacts on global climate (please review the Chapter 4 Geosystems Now).
Ice Sheet Darkening Satellite measurements show that on the Greenland Ice Sheet, the reflectivity of the snow and ice decreased over the past decade as the surface has darkened. Along the outer edges, ice melt exposed darker land, vegetation, and water surfaces. On the interior, black carbon from wildfires in Asia and North America accumulated on the ice and may be contributing to the overall darkening (Figure 17.29). Another factor may be related to basic processes of snow metamorphism: As temperatures rise, snow crystals clump together in the snow pack, reflecting less light than the smaller, faceted individual crystals. The overall effect is that the ice sheet now absorbs more sunlight, which speeds up melting and causes a positive feedback that accelerates warming.
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(c) The Antarctic convergence designates the Antarctic region. ▲Figure 17.28 The Arctic and Antarctic regions.
[(b) Bobbé Christopherson.]
Recent Polar Region Changes
As mentioned earlier, the smallest extent of Arctic sea ice on record occurred in the year 2012. About half of Arctic sea-ice volume disappeared since 1970 due to warming throughout the region. As discussed in Chapter 4 Geosys- tems Now, the fabled Northwest Passage across the Arctic from the Atlantic to the Pacific is now ice-free for a por- tion of the summer as the Arctic ice continues to melt. The Northeast Passage, north of Russia, has been ice-free for the past several years. These changes affect surface
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Chapter 17 glacial and Periglacial Landscapes 559