30 years after NASA's warning, global warming 'is hitting us hard,' scientists say

Arctic warming has effects as far south as Nebraska and Iowa. Emerging research indicates that loss of ice in the Arctic could be a key driver of increasingly extreme weather in the continental U.S., including heat waves and cold spells.

The melting ice is enough to raise the level of the seas. Overall, NASA satellites have shown three inches of sea level rise in just the past 25 years. That increase amounts to 6,500 cubic miles of extra water, enough to cover the entire United States with about 9 feet of water.