Quantifying historical trends in tropical cyclone activity has proved difficult, but a new reconstruction reveals a clear global decline over the past century, driven by an increasingly cyclone-hostile environment in the troposphere.

中文翻译：

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全球频率下降

量化热带气旋活动的历史趋势已被证明是困难的，但一项新的重建揭示了过去一个世纪全球明显下降，这是由对流层中越来越不利的气旋环境驱动的。