Arctic sea ice has melted dramatically this summer, smashing the previous record. The Arctic has warmed dramatically compared with the rest of the planet, and scientists say that's what's driving this loss of ice.
To be sure, ice on the Arctic Ocean always melts in the summer. Historically, about half of it is gone by mid-September. But this year, three-fourths of the ice has melted away, setting a dramatic new benchmark.
From Backstory with the American History Guys: in 1815, a volcanic eruption in Indonesia sent enough ash into the sky to disrupt the world’s weather for the next year. In New England, 1816 became known as “The Year Without a Summer.” Snow fell in June and July. Crops and animals died. Tens of thousands of people picked up and left; their search for greener pastures became an early chapter in a larger story of westward expansion.