Because of natural decadal climate variability—Atlantic multi-decadal variability (AMV) and Pacific decadal variability (PDV) —the increase of global mean surface air temperature (GMSAT) has not been monotonic although atmospheric greenhouse-gas (GHG) concentrations have been increasing continuously. It has always been a challenge regarding how to separate the effects of these two factors on GMSAT. Here, we find a physically based quasi-linear relationship between transient GMSAT and well-mixed GHG changes for both observations and model simulations. With AMV and PDV defined as the combination of variability over both the Atlantic and Pacific basins after the GHG-related trend is removed, we show that the observed GMSAT changes from 1880 to 2017 on multi-decadal or longer timescales receive contributions of about 70% from GHGs, while AMV and PDV together account for roughly 30%. Moreover, AMV contributes more to time-evolving GMSAT on multi-decadal and longer timescales, but PDV leads AMV on decadal timescales with comparable contributions to GMSAT trends.

由于自然年代际气候变率（大西洋多年代际变率（AMV）和太平洋年代际变率（PDV）），尽管大气温室气体（GHG）浓度一直在增加，但全球平均地表温度（GMSAT）的增加并不是单调的不断地。如何区分这两个因素对GMSAT的影响一直是一个挑战。在这里，我们发现了瞬态GMSAT和良好混合的GHG变化之间基于物理的准线性关系，用于观测和模型模拟。将AMV和PDV定义为消除与温室气体有关的趋势后大西洋和太平洋海盆的变异性的组合，我们表明，从观测到的GMSAT从1880年到2017年的变化，在数十年或更长时间的尺度上得到的贡献约为70％来自温室气体，而AMV和PDV约占30％。而且，AMV在多年代和更长的时间尺度上对时间演化的GMSAT的贡献更大，但是PDV在十年时间尺度上领先AMV，对GMSAT趋势具有可比的贡献。