To avoid the worst impacts of climate change, the Paris Agreement committed countries to pursue efforts to limit global warming to 1.5 °C by urgently reducing greenhouse gas emissions. However, the Paris temperature ambitions and remaining carbon budgets mostly use models that lack feedback among fire, vegetation and carbon, which are essential for understanding the future resilience of ecosystems. Here we use a coupled fire–vegetation model to explore regional impacts and feedbacks across global warming levels. We address whether the 1.5 °C goal is consistent with avoiding significant ecosystem changes when considering shifts in fire regimes. We find that the global warming level at which fire began to impact global carbon storage significantly was 1.07 °C (0.8–1.34 °C) above pre-industrial levels and conclude that fire is already playing a major role in decreasing the effectiveness of land carbon sinks. We estimate that considering fire reduces the remaining carbon budget by 25 Gt CO₂ (~5%) for limiting temperature rise to 1.5 °C and 64 GtCO₂ (~5%) for 2.0 °C compared to previous estimates. Whereas limiting warming to 1.5 °C is still essential for avoiding the worst impacts of climate change, in many cases, we are already reaching the point of significant change in ecosystems rich in carbon and biodiversity.

为避免气候变化的最坏影响，《巴黎协定》承诺各国努力通过紧急减少温室气体排放，将全球变暖限制在 1.5 °C 以内。然而，巴黎气候雄心和剩余碳预算大多使用缺乏火灾、植被和碳之间反馈的模型，这对于理解生态系统的未来复原力至关重要。在这里，我们使用火-植被耦合模型来探索全球变暖水平的区域影响和反馈。我们讨论了 1.5 °C 的目标是否与在考虑火灾状况变化时避免重大生态系统变化一致。我们发现，火灾开始显著影响全球碳储存的全球变暖水平比工业化前水平高出 1.07 °C （0.8–1.34 °C），并得出结论，火灾已经在降低土地碳汇的有效性方面发挥了重要作用。我们估计，与之前的估计相比，考虑到火灾，将温度上升限制在 1.5 °C 的剩余碳预算减少了 25 Gt CO₂ （~5%），将温度上升限制在 2.0 °C 的剩余碳预算减少了 64 GtCO₂ （~5%）。虽然将升温限制在 1.5 °C 对于避免气候变化的最坏影响仍然至关重要，但在许多情况下，我们已经达到了富含碳和生物多样性的生态系统发生重大变化的地步。