El Niño–Southern Oscillation (ENSO) is the strongest mode of interannual climate variability in the current climate, influencing ecosystems, agriculture, and weather systems across the globe, but future projections of ENSO frequency and amplitude remain highly uncertain. A comparison of changes in ENSO in a range of past and future climate simulations can provide insights into the sensitivity of ENSO to changes in the mean state, including changes in the seasonality of incoming solar radiation, global average temperatures, and spatial patterns of sea surface temperatures. As a comprehensive set of coupled model simulations is now available for both palaeoclimate time slices (the Last Glacial Maximum, mid-Holocene, and last interglacial) and idealised future warming scenarios (1 % per year CO₂ increase, abrupt four-time CO₂ increase), this allows a detailed evaluation of ENSO changes in this wide range of climates. Such a comparison can assist in constraining uncertainty in future projections, providing insights into model agreement and the sensitivity of ENSO to a range of factors. The majority of models simulate a consistent weakening of ENSO activity in the last interglacial and mid-Holocene experiments, and there is an ensemble mean reduction of variability in the western equatorial Pacific in the Last Glacial Maximum experiments. Changes in global temperature produce a weaker precipitation response to ENSO in the cold Last Glacial Maximum experiments and an enhanced precipitation response to ENSO in the warm increased CO₂ experiments. No consistent relationship between changes in ENSO amplitude and annual cycle was identified across experiments.

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CMIP5 / PMIP3和CMIP6 / PMIP4模型中ENSO过去和未来模拟的比较

厄尔尼诺－南方涛动（ENSO）是当前气候中最强的年际气候变化模式，影响着全球的生态系统，农业和天气系统，但是ENSO频率和振幅的未来预测仍然高度不确定。比较ENSO在过去和将来的气候模拟范围内的变化，可以洞悉ENSO对平均状态变化的敏感性，包括太阳辐射的季节性变化，全球平均温度和海表空间格局的变化温度。作为一整套综合的耦合模型模拟，现在可用于古气候时间段（最后一次冰期最大值，全新世中期和最后一次冰期之间）和理想的未来变暖情景（每年1％CO ₂增加，突然四次 增加CO ₂），这可以详细评估ENSO在这种广泛气候中的变化。这样的比较可以帮助限制未来预测的不确定性，提供对模型一致性以及ENSO对一系列因素的敏感性的见解。大多数模型都模拟了最近一次冰间期和全新世中期实验中ENSO活性的持续减弱，并且在最近一次冰期最大实验中，赤道西太平洋的总体变率平均降低了。全球温度的变化在冷的上一次冰河最大实验中对ENSO的降水响应较弱，而在温暖的CO ₂增加的情况下对ENSO的降水响应有所增强。 实验。在整个实验中，未确定ENSO振幅变化与年周期之间的一致性关系。