Temperature sensitivity--the magnitude of a biological response per °C--is a fundamental concept across scientific disciplines, especially biology, where temperature determines the rate of many plant, animal and ecosystem processes. Recently, a growing body of literature in global change biology has found temperature sensitivities decline as temperatures rise (1; 2; 3; 4). Such observations have been used to suggest climate change is reshaping biological processes, with major implications for forecasts of future change. Here we present a simple alternative explanation for observed declining sensitivities: the use of linear models to estimate non-linear temperature responses. We show how linear estimates of sensitivities will appear to decline with warming for events that occur after a cumulative thermal threshold is met---a common model for many biological events. Corrections for the non-linearity of temperature response in simulated data and long-term phenological data from Europe remove the apparent decline. Our results show that rising temperatures combined with linear estimates based on calendar time produce observations of declining sensitivity---without any shift in the underlying biology. Current methods may thus undermine efforts to identify when and how warming will reshape biological processes.

中文翻译：

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随温度降低温度敏感性的简单解释

温度敏感性-每°C的生物反应幅度-是整个科学学科（尤其是生物学）的基本概念，在该学科中，温度决定着许多植物，动物和生态系统过程的速率。最近，全球变化生物学中越来越多的文献发现温度敏感性随着温度的升高而下降（1、2、3、4）。此类观察已被用来暗示气候变化正在重塑生物过程，对未来变化的预测具有重大意义。在这里，我们为观察到的灵敏度下降提供了一种简单的替代解释：使用线性模型来估计非线性温度响应。我们展示了对于满足累积热阈值之后发生的事件而言，随着温度升高，敏感性的线性估计将如何下降-这是许多生物学事件的通用模型。来自欧洲的模拟数据和长期物候数据中对温度响应非线性的校正消除了明显的下降。我们的结果表明，温度升高与基于日历时间的线性估计相结合，可以观察到灵敏度下降的现象-底层生物学没有任何变化。因此，当前的方法可能会破坏识别变暖何时以及如何重塑生物过程的努力。我们的结果表明，温度升高与基于日历时间的线性估计相结合，可以观察到灵敏度下降的现象-底层生物学没有任何变化。因此，当前的方法可能会破坏识别变暖何时以及如何重塑生物过程的努力。我们的结果表明，温度升高与基于日历时间的线性估计相结合，可以观察到灵敏度下降的现象-底层生物学没有任何变化。因此，当前的方法可能会破坏识别变暖何时以及如何重塑生物过程的努力。