Arctic ice pack

Rising Global Sea Levels Global average sea level has risen by about 7 to 8 inches, about 16 to 21 centimeters, since 1900, with almost half this rise occurring since 1993 as oceans have warmed and land-based ice has melted.

Relative to the year 2000, sea level is very likely to rise 1 to 4 feet, 0.3 to 1.3 meters, by the end of the century.

Emerging science regarding Antarctic ice sheet stability suggests that, for higher scenarios, a rise exceeding 8 feet, 2.4 meters, by 2100 is physically possible, although the probability of such an extreme outcome cannot currently be assessed.

Key Message five: Increasing U.S. temperatures.

Annual average temperature over the contiguous United States has increased by one point two degrees Fahrenheit, zero point seven degrees Celsius, over the last few decades, and by one point eight degrees Fahrenheit, one degree Celsius, relative to the beginning of the last century.

Key Message nine: Increases in coastal flooding.

Regional changes in sea level rise and coastal flooding are not evenly distributed across the United States.

Ocean circulation changes, sinking land, and Antarctic ice melt will result in greater than average sea level rise for the Northeast and western Gulf of Mexico under lower scenarios and most of the U.S. coastline other than Alaska under higher scenarios.