1 Since 1850:Ref: IPCC- AR4 Temperature is up 1°C (1.8°F) and climbing steeply Sea Level is up 2...

1 Light colored ice reflects back the Sun’s energy efficiently. 2 Exposed land is darker and absorbs more energy; warming. 3 As the ice melts, more land is exposed. This absorbs more heat, melting more ice, and causing further warming. 4 The altitude of the melting ice is reduced so it becomes harder for new ice to form (esp for Greenland). Positive Feedback: Some Warming Causes More Warming! Ice-melt Positive Feedback can cause a Runaway Warming, by darkening originally-light surfaces. Indeed, ice is melting MUCH faster than glaciologists had forecast: Since the inhabited Earth has never experienced these conditions, there were no observations of rapidly melting ice on which to base predictions. Melt descending into a moulin, a vertical shaft carrying water to the base of the Greenland ice sheet.