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The ice sheet, which covers seven-eighths of the land's surface, contains an estimated 11 percent of the world's fresh water. During the last 110,000 years it is believed there have been at least 23 ice warming periods in Greenland - like the one we see happening now. The discovery of abrupt climatic shifts, or Dansgaard-Oeschger oscillations, has been the most surprising element in ice core research and baffles scientists.

The last glacial period show temperature increases over Greenland of up to 6 degrees Celsius, in a time span of less than a decade. This has prompted great interest in the causes of such a dramatic change, and has led to speculation that the current increasing levels of greenhouse gases in the atmosphere might trigger such change in the coming decades. The problem is that the exposed ocean water will reflect less solar rays than ice. This causing a further warming of the atmosphere. Without other factors intervening, the additional warming will lead to more breakup of ice. Additional melt water from the ice will bring large fluxes of freshwater into the north Atlantic causing a buoyancy effect from the much less saline water.

The cold waters will cease to sink, and the low undercurrent flow is likely to considerably weaken, halting the Atlantic thermo circulation. The Gulf Stream, a major part of the clockwise-rotating system of currents in the Atlantic, the North Atlantic Drift, and other currents will be affected by a large influx of freshwater. Research by Australian scientists has suggested that a 3C rise in global temperatures would be enough to trigger the melting of the Greenland ice sheet. In 2006, research conducted by researchers at Nasa suggested that the rate of melting of the giant ice sheet had tripled since 2004. A complete melt of the ice sheet would cause a global sea level rise of about 7m and 23m if Antarctica were to go!