There is broad scientific consensus that the Earth is warmer than it has been at any time in the last 1, 000 years, but researchers say it still isn't clear whether the polar climate changes are due entirely to that warming _ or to some still unidentified long-term cycles in atmospheric and ocean circulation.
42.
Many glaciers from temperate, alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant.
43.
The weather on Shemya is very drastic, though the temperatures only vary between single digits to the mid fifties, and the climate is perhaps the most equatorward low-altitude occurrence of a polar climate ( " ET " ) in the world, though it is extremely close to a subpolar oceanic climate ( " Cfc " ).
44.
The boundary between the microthermal and polar climate zones is farthest north in western Europe ( actually within the Arctic Circle there ), and farthest south along the east coast of North America ( at about 56?North latitude on the central coast of Labrador ); it then trends northward across Canada before dropping south again as it courses through Alaska.
