The differential climatic impact between the 1.5° versus 2°C warmer worlds is a global concern on the post‐Paris science agenda. The recently released Intergovernmental Panel on Climate Change (IPCC) special report “Global Warming of 1.5ºC” (hereafter SR15) concludes robustly avoided impacts from climate extremes from the 0.5°C less warming globally, based on multiple lines of evidence. However, the methodological uncertainties, including those arising from modeling strategy (i.e., different pathways to achieve the temperature targets), remain a knowledge gap. Here, by comparing simulations with the common Community Atmosphere Model (CAM5) using different modeling strategies (i.e., fully coupled transient, fully coupled quasi‐equilibrium, and atmosphere‐only quasi‐equilibrium simulations), we explored the uncertainty from modeling strategy in the reduced impacts of climate extremes from the half‐degree less warming. While the globally aggregated reduced impacts are reasonably consistent among modeling strategies, substantial quantitative uncertainties of reduced impact exist at regional scales. For temperature extremes, the largest methodological uncertainty exists in northern high‐latitudes, especially in Europe and North America, with spread exceeding 0.8°C. For precipitation extremes, large uncertainties (even opposite signs) are expected scatteredly over the globe, particularly in the populous South Asia for wet extremes, and in South‐East Asia, West North America, and the Amazon for dry extremes, with spread of ∼5%. The different regional responses among modeling strategies result from multiple physical processes, dominated by the transient versus quasi‐equilibrium responses, prescribed sea surface temperatures and aerosol forcing. The comparisons improve the understanding of methodological uncertainties in the projected impacts in light of model setups.

中文翻译：

---

建模策略对0.5°C的温差影响评估的影响

1.5°和2°C变暖世界之间气候差异的影响是巴黎后科学议程中的全球关注点。政府间气候变化专门委员会（IPCC）最近发布的特别报告“ 1.5°C的全球变暖””（以下称SR15）基于多条证据，得出结论，强烈避免了全球变暖少0.5°C的极端气候所造成的影响。但是，方法学上的不确定性，包括那些因建模策略而产生的不确定性（即，实现温度目标的不同途径），仍然存在知识空白。在这里，通过使用不同的建模策略（即完全耦合的瞬态，完全耦合的准平衡和仅大气的准平衡仿真）将模拟与常见的社区大气模型（CAM5）进行比较，我们探索了模型策略中的不确定性。减少了半度的变暖，从而减少了极端气候的影响。虽然各建模策略在全球范围内所产生的减少影响是合理一致的，在区域范围内，减少影响的数量上存在大量不确定性。对于极端温度，方法的最大不确定性存在于北部高纬度地区，尤其是在欧洲和北美，其传播超过0.8°C。对于极端降水，预计在全球范围内散布着很大的不确定性（甚至是相反的迹象），尤其是在人口稠密的南亚，极端潮湿的地区，以及在东南亚，西北美和亚马逊地区，对于极端干旱的地区，其扩散范围约为-。 5％。建模策略之间不同的区域响应是由多个物理过程引起的，这些过程主要是瞬态响应与准平衡响应，规定的海面温度和气溶胶强迫作用。