Warming temperatures in the Northern Hemisphere have enhanced terrestrial productivity. Despite the warming trend, North America has experienced more frequent and more intense cold weather events during winters and springs. These events have been linked to anomalous Arctic warming since 1990, and may affect terrestrial processes. Here we analyse multiple observation data sets and numerical model simulations to evaluate links between Arctic temperatures and primary productivity in North America. We find that positive springtime temperature anomalies in the Arctic have led to negative anomalies in gross primary productivity over most of North America during the last three decades, which amount to a net productivity decline of 0.31 PgC yr⁻¹ across the continent. This decline is mainly explained by two factors: severe cold conditions in northern North America and lower precipitation in the South Central United States. In addition, United States crop-yield data reveal that during years experiencing anomalous warming in the Arctic, yields declined by approximately 1 to 4% on average, with individual states experiencing declines of up to 20%. We conclude that the strengthening of Arctic warming anomalies in the past decades has remotely reduced productivity over North America.

中文翻译：

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与北极变暖有关的北美陆地初级生产力下降

北半球变暖的温度提高了陆地生产力。尽管有变暖的趋势，北美在冬季和春季却经历了更频繁，更强烈的寒冷天气事件。自1990年以来，这些事件一直与北极异常变暖有关，并可能影响陆地进程。在这里，我们分析了多个观测数据集和数值模型模拟，以评估北极温度与北美初级生产力之间的联系。我们发现，在过去的三十年中，北极大部分地区的春季正温度异常导致总初级生产力的负异常，这意味着净生产力下降了0.31  PgC  yr ^-1遍及整个大陆。这种下降主要由两个因素解释：北美北部的严寒和美国中南部的降水减少。此外，美国的农作物单产数据显示，在北极经历异常变暖的年份中，单产平均下降了大约1-4％，而个别州的单产下降了20％。我们得出的结论是，在过去的几十年中，北极变暖异常的加剧大大降低了北美的生产力。