total loss of Arctic sea ice cover from June to September would increase the global temperatures by 0.19 degrees Celsius, with a range of 0.16–0.21 °C, while the regional temperatures would increase by over 1.5 degrees. This estimate includes not just the ice-albedo feedback itself, but also its second-order effects such the impact of such sea ice loss on lapse rate feedback, the changes in water vapor concentrations and regional cloud feedbacks. Since these calculations are already part of every CMIP5 and CMIP6 model, they are also included in their warming projections under every climate change pathway, and do not represent a source of "additional" warming on top of their existing projections. Very high levels of global warming could prevent Arctic sea ice from reforming during the Arctic winter. Unlike an ice-free summer, this ice-free Arctic winter may represent an irreversible tipping point. It is most likely to occur at around 6.3 degrees Celsius, though it could potentially occur as early as 4.5 °C or as late as 8.7 °C. While the Arctic sea ice would be gone for an entire year, it would only have an impact on the ice-albedo feedback during the months where sunlight is received by the Arctic - i.e. from March to September. The difference between this total loss of sea ice and its 1979 state is equivalent to a trillion tons of CO2 emissions - around 40% of the 2.39 trillion tons of cumulative emissions between 1850 and 2019, although around a quarter of this impact has already happened with the current sea ice loss. Relative to now, an ice-free winter would have a global warming impact of 0.6 degrees, with a regional warming between 0.6 and 1.2 degrees. Ice–albedo feedback also exists with the other large ice masses on the Earth's surface, such as mountain glaciers, Greenland ice sheet, West Antarctic and East Antarctic ice sheet. However, their large-scale melt is expected to take centuries or even millennia, and any loss in area by the end of the 21st century will be negligible. Thus, climate change models do not include them in their projections of 21st century climate change: experiments where they model the disappearance of those ice masses indicate that the total loss of the Greenland Ice Sheet adds 0.13 °C to global warming (with a range of 0.12–0.14 °C), while the loss of the West Antarctic Ice Sheet adds 0.05 °C