New evidence from over 4,600 studies calls into question the universal application of critical threshold values, or tipping points, along gradients of environmental stress. Identifying never-to-exceed environmental targets may prove elusive for environmental policy and management.

中文翻译：

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难以捉摸的寻找临界点。

来自 4,600 多项研究的新证据质疑关键阈值或临界点沿环境压力梯度的普遍应用。对于环境政策和管理而言，确定永不超过的环境目标可能难以实现。