section_path: Global temperature rise/Future global temperatures
section_name: Future global temperatures
paragraph_text: Future global temperatures
  
  The World Meteorological Organization estimates a 66% chance of global temperatures exceeding 1.5 °C warming from the preindustrial baseline for at least one year between 2023 and 2027. Because the IPCC uses a 20-year average to define global temperature changes, a single year exceeding 1.5 °C does not break the limit.
  
  The IPCC expects the 20-year average global temperature to exceed +1.5 °C in the early 2030s. The IPCC Sixth Assessment Report (2023) included projections that by 2100 global warming is very likely to reach 1.0-1.8 °C under a scenario with very low emissions of greenhouse gases, 2.1-3.5 °C under an intermediate emissions scenario,or 3.3-5.7 °C under a very high emissions scenario. The warming will continue past 2100 in the intermediate and high emission scenarios, with future projections of global surface temperatures by year 2300 being similar to millions of years ago.
  
  The remaining carbon budget for staying beneath certain temperature increases is determined by modelling the carbon cycle and climate sensitivity to greenhouse gases. According to the IPCC, global warming can be kept below 1.5 °C with a two-thirds chance if emissions after 2018 do not exceed 420 or 570 gigatonnes of CO. This corresponds to 10 to 13 years of current emissions. There are high uncertainties about the budget. For instance, it may be 100 gigatonnes of CO equivalent smaller due to CO and methane release from permafrost and wetlands. However, it is clear that fossil fuel resources need to be proactively kept in the ground to prevent substantial warming. Otherwise, their shortages would not occur until the emissions have already locked in significant long-term impacts.