In 2007, the Intergovernmental Panel on Climate Change (IPCC) made a big splash, stating that global sea levels may rise between 18 centimeters and 59 centimeters by 2100 . But those numbers were fraught with uncertainties—the most looming of which was the potential contribution to sea-level rise from melting of the giant ice sheets now blanketing Greenland and Antarctica. So the European Union's science funding program, Framework 7, created a research consortium, dubbed ice2sea , to study ice loss processes on continents (such as what hastens calving, pictured above in Greenland) as a way to estimate how much continental ice will add to future sea-level rise. Today, scant months before IPCC prepares to release its fifth assessment in September, ice2sea scientists released a preview of their findings. The upshot: Assuming a midrange emissions scenario, ice sheets and continental glaciers alone will contribute between 3.5 centimeters and 36.8 centimeters of sea-level rise by 2100. In the worst-case scenario (the likelihood of this happening is 1 in 20), continental ice melting could produce 84 centimeters of sea-level rise—not counting potential contributions from other sources, particularly thermal expansion (water expands as it warms). Even 90 centimeters of sea-level rise would hit coastal areas hard, producing routine flooding in low-lying cities such as Miami and New York. But the real inundation might come after 2100. Antarctica's rapidly retreating Pine Island Glacier is a sort of poster child for ice loss in Antarctica, and its retreat seems likely to continue to the end of the century even as the rest of the Antarctic ice sheet remains fairly stable. Moving into the next century, neighboring Thwaites Glacier could become destabilized, potentially adding tens of centimeters to sea-level rise—and that will really make a splash.
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