of the ice sheet is inevitable. Climate models project that local warming in Greenland will be to during this century. Ice sheet models project that such a warming would initiate the long-term melting of the ice sheet, leading to a complete melting of the ice sheet (over centuries), resulting in a global sea level rise of about . Such a rise would inundate almost every major coastal city in the world. How fast the melt would eventually occur is a matter of discussion. According to the IPCC 2001 report, such warming would, if kept from rising further after the 21st Century, result in 1 to 5 meter sea level rise over the next millennium due to Greenland ice sheet melting. Some scientists have cautioned that these rates of melting are overly optimistic as they assume a linear, rather than erratic, progression. James E. Hansen has argued that multiple positive feedbacks could lead to nonlinear ice sheet disintegration much faster than claimed by the IPCC. According to a 2007 paper, "we find no evidence of millennial lags between forcing and ice sheet response in paleoclimate data. An ice sheet response time of centuries seems probable, and we cannot rule out large changes on decadal time-scales once wide-scale surface melt is underway." In a 2013 study published in Nature, 133 researchers analyzed a Greenland ice core from the Eemian interglacial. They concluded that during this geological period, roughly 130,000–115,000 years ago, the GIS (Greenland Ice Sheet) was warmer than today. This resulted in a thickness decrease of the northwest Greenland ice sheet by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than at present. A 2021 analysis of sub-glacial sediment at the bottom of a 1.4 km Greenland ice core finds that the Greenland ice sheet melted away at least once during the last million years, indicating that its tipping point is below the maximum warming relative to the preindustrial conditions over that period. A 2022 assessment of tipping points in the climate system estimated that the Greenland ice sheet would most likely be committed to long-term disintegration around of global warming: in the best case, its disintegration would not be set in motion until , but in the worst case, it could already be inevitable unless the global warming is reduced below . At the same time, it noted that the fastest plausible