Earth from Space: Gifts from the ice age
This Envisat image features the mountains, glaciers and icefields in southeastern Alaska and British Columbia, Canada.
The climate and topography of this area over the last 12.5 million years have been favourable for glaciers. During the Ice Age, a vast ice sheet covered this spot. When temperatures warmed up, an interglacial period began.
The coastal mountains and the maritime climate of this area provide the perfect setting for glaciation: some of the world’s longest and most spectacular glaciers are found here.
Hubbard Glacier (bottom centre), the largest tidewater glacier in North America, spans the US–Canadian border. Its source is in Canada’s Yukon Territory (roughly right of centre), and it stretches across Alaska (left) into Disenchantment Bay, the mouth of Yakutat Bay.
The pancake-shaped Malaspina Glacier is west of Yakutat Bay. Its unique shape is the result of steep valley glaciers flowing onto a relatively flat plain where it spreads out; this type of glacier is called a piedmont.
Covering nearly 4000 sq km, Malaspina is the largest piedmont glacier in the world. In fact, it is so large that it can only be seen in its entirety from space. North America’s largest and longest glacier, the Bering Glacier (west of Malaspina), covers 5200 sq km and is over 200 km long.
The Chugach Mountains, which contain the state’s greatest concentration of glacial ice, extend along the coast above the Malaspina and Bering glaciers. When warm, wet air flows off the Pacific Ocean and meets the cool temperatures of this mountain range some of the highest snowfall in Alaska is created.
The majority of snow-covered areas to the left of Hubbard Glacier belongs to Wrangell-St. Elias National Park. Directly above Hubbard sits the Kluane National Park, home to the world's largest non-polar icefields.
The most easterly patch of white on the coast is Glacier Bay Park. Nestled between Kluane and Glacier Bay is the Tatshenshini-Alsek Park, which boasts a magnificent river system.
These national parks combine to form an international park system that comprises the largest protected area in the world. In 1979, the park system was declared a UNESCO World Heritage Site for its spectacular glacier and icefield landscapes and for providing an important habitat for grizzly bears and caribou.
This image was acquired by Envisat’s Medium Resolution Imaging Spectrometer on 20 September 2010 at a resolution of 300 m.