AbstractThe impacts of land use have been shown to have considerable influence on regional climate. With the recent international commitment to limit global warming to well below 2°C, emission reductions need to be ambitious and could involve major land‐use change (LUC). Land‐based mitigation efforts to curb emissions growth include increasing terrestrial carbon sequestration through reforestation, or the adoption of bioenergy crops. These activities influence local climate through biogeophysical feedbacks, however, it is uncertain how important they are for a 1.5° climate target. This was the motivation for HAPPI‐Land: the half a degree additional warming, prognosis, and projected impacts—land‐use scenario experiment. Using four Earth system models, we present the first multimodel results from HAPPI‐Land and demonstrate the critical role of land use for understanding the characteristics of regional climate extremes in low‐emission scenarios. In particular, our results show that changes in temperature extremes due to LUC are comparable in magnitude to changes arising from half a degree of global warming. We also demonstrate that LUC contributes to more than 20% of the change in temperature extremes for large land areas concentrated over the Northern Hemisphere. However, we also identify sources of uncertainty that influence the multimodel consensus of our results including how LUC is implemented and the corresponding biogeophysical feedbacks that perturb climate. Therefore, our results highlight the urgent need to resolve the challenges in implementing LUC across models to quantify the impacts and consider how LUC contributes to regional changes in extremes associated with sustainable development pathways.

中文翻译：

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低排放情景下土地利用变化对极端气候的生物地球物理影响：HAPPI-Land 的结果


摘要土地利用的影响已被证明对区域气候有相当大的影响。随着最近国际社会承诺将全球变暖幅度限制在 2°C 以下，减排工作必须雄心勃勃，并且可能涉及重大的土地利用变化 (LUC)。遏制排放增长的陆地缓解措施包括通过重新造林或采用生物能源作物增加陆地碳固存。这些活动通过生物地球物理反馈影响当地气候，但尚不确定它们对于 1.5° 气候目标有多重要。这就是 HAPPI-Land 的动机：半度额外变暖、预测和预计影响——土地利用情景实验。使用四个地球系统模型，我们展示了 HAPPI-Land 的第一个多模型结果，并证明了土地利用对于了解低排放情景下区域极端气候特征的关键作用。特别是，我们的结果表明，LUC 引起的极端温度变化的幅度与全球变暖半度引起的变化相当。我们还证明，对于集中在北半球的大片陆地区域，土地利用变化对极端温度变化的贡献率超过 20%。然而，我们还确定了影响我们结果的多模型共识的不确定性来源，包括 LUC 的实施方式以及扰乱气候的相应生物地球物理反馈。因此，我们的研究结果强调，迫切需要解决跨模型实施土地利用变化的挑战，以量化影响，并考虑土地利用变化如何促进与可持续发展路径相关的区域极端变化。