Evidence-based responses to climate change by society require operational and sustained information including biophysical indicator systems that provide up-to-date measures of trends and patterns against historical baselines. Two key components linking anthropogenic climate change to impacts on socio-ecological systems are the periodic inter- and intra-annual variations in physical climate systems (seasonality) and in plant and animal life cycles (phenology). We describe a set of national indicators that reflect sub-seasonal to seasonal drivers and responses of terrestrial physical and biological systems to climate change and variability at the national scale. Proposed indicators and metrics include seasonality of surface climate conditions (e.g., frost and freeze dates and durations), seasonality of freeze/thaw in freshwater systems (e.g., timing of stream runoff and durations of lake/river ice), seasonality in ecosystem disturbances (e.g., wildfire season timing and duration), seasonality in vegetated land surfaces (e.g., green-up and brown-down of landscapes), and seasonality of organismal life-history stages (e.g., timings of bird migration). Recommended indicators have strong linkages to variable and changing climates, include abiotic and biotic responses and feedback mechanisms, and are sufficiently simple to facilitate communication to broad audiences and stakeholders interested in understanding and adapting to climate change.

中文翻译：

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生物和物理系统的季节性作为气候变化和变化的指标

社会对气候变化的循证响应需要可操作和持续的信息，包括生物物理指标系统，这些系统可根据历史基线提供最新的趋势和模式测量值。将人为气候变化与社会生态系统影响联系起来的两个关键组成部分是物理气候系统（季节性）和植物和动物生命周期（物候）的周期性年际和年内变化。我们描述了一组国家指标，这些指标反映了次季节到季节性的驱动因素以及陆地物理和生物系统对国家范围内气候变化和变异的反应。提议的指标和度量包括地表气候条件的季节性（例如，霜冻和冻结日期和持续时间）、淡水系统中冻结/解冻的季节性（例如，径流的时间和湖/河冰的持续时间）、生态系统干扰的季节性（例如，野火季节的时间和持续时间）、植被地表的季节性（例如，景观的绿化和褐化）以及有机体的季节性生活史阶段（例如，鸟类迁徙的时间）。推荐的指标与可变和不断变化的气候有很强的联系，包括非生物和生物反应和反馈机制，并且足够简单，便于与对理解和适应气候变化感兴趣的广大受众和利益相关者进行交流。和生物生命史阶段的季节性（例如，鸟类迁徙的时间）。推荐的指标与可变和不断变化的气候有很强的联系，包括非生物和生物反应和反馈机制，并且足够简单，便于与对理解和适应气候变化感兴趣的广大受众和利益相关者进行交流。和生物生命史阶段的季节性（例如，鸟类迁徙的时间）。推荐的指标与可变和不断变化的气候有很强的联系，包括非生物和生物反应和反馈机制，并且足够简单，便于与对理解和适应气候变化感兴趣的广大受众和利益相关者进行交流。