A critical question for climate mitigation and adaptation is to understand when and where the signal of changes to climate extremes have persistently emerged or will emerge from the background noise of climate variability. Here we show observational evidence that such persistent changes to temperature extremes have already occurred over large parts of the Earth. We further show that climate models forced with natural and anthropogenic historical forcings underestimate these changes. In particular, persistent changes have emerged in observations earlier and over a larger spatial extent than predicted by models. The delayed emergence in the models is linked to a combination of simulated change ('signal') that is weaker than observed, and simulated variability ('noise') that is greater than observed. Over regions where persistent changes had not occurred by the year 2000, we find that most of the observed signal-to-noise ratios lie within the 16-84% range of those simulated. Examination of simulations with and without anthropogenic forcings provides evidence that the observed changes are more likely to be anthropogenic than nature in origin. Our findings suggest that further changes to temperature extremes over parts of the Earth are likely to occur earlier than projected by the current climate models.

中文翻译：

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广泛的温度极限持续变化发生的时间比预期的要早。

缓解和适应气候变化的一个关键问题是要了解气候极端变化的信号在何时何地持续出现或将从气候可变性的背景噪声中出现。在这里，我们显示出观察证据，表明这种极端温度的持续变化已经在地球的大部分地区发生。我们进一步表明，受自然和人为历史强迫强迫的气候模型低估了这些变化。特别是，在观测中出现的持续性变化比模型所预测的更早，且发生的空间范围更大。模型中出现的延迟与弱于所观察到的模拟变化（“信号”）和大于所观察到的模拟变异（“噪声”）的组合有关。在到2000年尚未发生持续变化的区域上，我们发现观察到的大多数信噪比都在模拟值的16-84％范围内。对有无人为强迫的模拟进行的检验提供了证据，表明所观察到的变化比原产地的自然性更可能是人为的。我们的发现表明，地球局部温度极限的进一步变化可能要比当前气候模型预测的更早发生。