Parties to the 2015 Paris Agreement pledged to limit global warming to well below 2 °C and to pursue efforts to limit the temperature increase to 1.5 °C relative to pre-industrial times¹. However, fossil fuels continue to dominate the global energy system and a sharp decline in their use must be realized to keep the temperature increase below 1.5 °C (refs. ^2,3,4,5,6,7). Here we use a global energy systems model⁸ to assess the amount of fossil fuels that would need to be left in the ground, regionally and globally, to allow for a 50 per cent probability of limiting warming to 1.5 °C. By 2050, we find that nearly 60 per cent of oil and fossil methane gas, and 90 per cent of coal must remain unextracted to keep within a 1.5 °C carbon budget. This is a large increase in the unextractable estimates for a 2 °C carbon budget⁹, particularly for oil, for which an additional 25 per cent of reserves must remain unextracted. Furthermore, we estimate that oil and gas production must decline globally by 3 per cent each year until 2050. This implies that most regions must reach peak production now or during the next decade, rendering many operational and planned fossil fuel projects unviable. We probably present an underestimate of the production changes required, because a greater than 50 per cent probability of limiting warming to 1.5 °C requires more carbon to stay in the ground and because of uncertainties around the timely deployment of negative emission technologies at scale.

2015 年《巴黎协定》缔约方承诺将全球变暖限制在远低于 2°C 的范围内，并努力将相对于工业化前时期的温度升高限制在 1.5°C 以内¹。然而，化石燃料继续在全球能源系统中占主导地位，必须实现其使用量的急剧下降，以将温度升高保持在 1.5°C 以下（参考文献^{2、3、4、5、6、7}）。这里我们使用全球能源系统模型⁸评估需要在区域和全球范围内留在地下的化石燃料数量，以将升温限制在 1.5°C 的可能性为 50%。到 2050 年，我们发现近 60% 的石油和化石甲烷气以及 90% 的煤炭必须保持未开采状态，才能将碳预算控制在 1.5°C 以内。这是对 2 °C 碳预算的不可提取估计值的大幅增加⁹，特别是石油，其额外 25% 的储量必须未被开采。此外，我们估计，到 2050 年，全球石油和天然气产量必须每年下降 3%。这意味着大多数地区现在或未来十年必须达到产量峰值，导致许多运营和计划中的化石燃料项目不可行。我们可能低估了所需的生产变化，因为将升温限制在 1.5°C 的可能性超过 50%，需要更多的碳留在地下，而且由于及时大规模部署负排放技术存在不确定性。