In 1853, for example, the American explorer Elisha Kent Kane sailed north to Greenland, determined to find an open polar sea and with it a shortcut to China.
42.
A summertime ice-free arctic would be unprecedented in recent geologic history, as currently scientific evidence does not indicate an ice-free polar sea anytime in the last 700, 000 years.
43.
The theory got a boost last week with new pictures by the Galileo spacecraft showing the moon's icy surface looking like pack ice in a polar sea on Earth.
44.
Meanwhile, they said in interviews and in the summary, evidence of increasing warming has shown up in retreating glaciers, thinning polar sea ice, retreating snowpacks, warmer nights and elsewhere.
45.
The milling cap of polar sea ice has thinned and shrunk, air temperatures high in the stratosphere have dropped sharply, and air and water at the sea surface have warmed.
46.
Petermann followed Bent in believing that a branch of the Kuro Siwo flowed through the Bering Strait, and might be powerful enough to create a path to the polar sea.
47.
After British naval expeditions in 1818 and 1827 28 had probed north of Spitsbergen and found no sign of the supposed polar sea, the quest was in abeyance for 25 years.
48.
The World Bank views the venture as a pilot project for further oil exploration and pipeline building in the region, which includes the ecologically sensitive North Polar Sea, the survey said.
49.
A condition assessment of the " Polar Sea " in August 2016 indicated that only one out of six of the 1, 200 system components were supportable for five years or more.
50.
Dr . Ronald Greeley, a planetary geologist from Arizona State University in Tempe, said the widespread phenomenon of ice blocks on Europa's surface resembled pack ice on Earth's polar seas during spring thaws.
