The coldest and highest parts of the Greenland ice sheet are warmer than any time in the last 1,000 years. The ice core analysis published Wednesday in Nature reveals temperatures already 1.5°C (2.7F) warmer than preindustrial averages. Researchers also observed a sharp increase between 1995 and 2011 — an ominous sign given the accelerating increase of global temperatures in the last decade. The findings are especially significant because increased melting can accelerate a feedback loop of ice sheet melt, thus further accelerating sea level rise worldwide. While research “adds momentum to the seriousness of the situation,” Isabella Velicogna, a UC-Irvine glaciologist not involved in the research, told the Washington Post. “This is bad, bad news for Greenland and for all of us.” (Washington Post $, AP, Inside Climate News, CNN; Climate Signals background: Glacier and sea ice melt, Arctic amplification, Sea level rise)