Answer: The release of methane from thawed permafrost
Explanation:
With increasing global warming, permafrost in the arctic is melting. The carbon and methyl clathrates present in permafrost escape into the atmosphere to form carbon dioxide and methane, both greenhouse gases.
In the Arctic, molecules of methane are trapped in ice crystals as methyl clathrates. When the temperature increases, these crystals release methyl clathrates which become methane when in contact with the atmosphere.
The cause of the increasing atmospheric 
is due to the the thawing of dead organisms present in the permafrost. As the permafrost melts, these organisms decay and release into the atmosphere.
Answer:
Precession
Explanation:
Various stars will act as northern stars due to precession, as well as the stars and planets arrayed around the celestial equator (zodiac) will steadily change locations. Every 73 years, they move around one degree. For the remainder of our days, and for a few millennia later, Polaris would stay the North Star.
Answer:
caliph - successor to Muhammad
Zionism - the movement to establish a Jewish state
Aliyah - immigrations of Jews to the holy land
diaspora - a group that is scattered outside it traditional homeland
Explanation:
After Muhammed died he was succeeded by Abu Bakr, the first of the caliphs. Because of internal conflicts, from 661 new Caliphate - Umayyad was established, although Abbasid Caliphate made even larger impact.
Jewish diaspora was created after the exile of Jews, from their homeland, most notably during the Babylonian captivity. They were scattered across the globe, but with the rise of Zionism movement in the second half of 19th Century, idea to return Jews to their homeland started spreading. Aliyah happened once more, as in the times of Abraham and Moses.
