The Greenland ice sheet — which contains almost 10 percent of all the frozen water on the planet — is melting at a rate of approximately 12 cubic miles per year, according to research by NASA scientists published in the journal Science. If melting continues at this rate, it could cause a measurable rise in sea levels, said the study’s lead author, William Krabill. The study, the most precise and comprehensive of its kind to date, does not specifically mention global warming, but some scientists say its findings are in line with climate change predictions.