It is widely accepted that accelerated Arctic warming will result in fewer and less harsh cold air outbreaks to the mid-latitudes. Yet, an increasing number of recent studies also argue that Arctic amplification can contribute to more severe winter weather. Judah Cohen, Principal Scientist at AER, led a study that showed that the temperature of cold extremes (defined as the coldest five percent of all winter days) across the United States east of the Rockies, Northeast Asia and Europe have remained nearly constant over recent decades, in clear contrast to a robust Arctic warming trend. Analysis of trends in the frequency and magnitude of cold extremes is mixed across the US and Asia but with a clearer decreasing trend in occurrence across Europe, especially Southern Europe. This divergence between robust Arctic warming and no detectable trends in mid-latitude cold extremes highlights the need for a better understanding of the physical links between accelerated Arctic warming and mid-latitude cold extremes.
Figure. A robust warming trend is observed in the Arctic but no consistent trend is found for Eastern US cold extremes. Frequency of Central-Eastern US (CEUS; shown in Figure 1) DJF 5% coldest events for a 1960–2023, b 1990–2023, and c 2000–2023, demarked with colored bars to represent each decade, and showing the linear trend line. The slope of the trend line is indicated in each panel (events/decade). The temperature for each cold CEUS event (colored dots) is shown in panels d, e and f for the same time periods as in panels a, b and c. Corresponding Arctic temperatures are shown with black dots. The trend lines indicate tendency in temperature over the ordered events, and the slope of the trend is indicated in each panel (°C per 30 events). Trend lines are shown solid if trend is significant at the 0.05 level, dashed otherwise.
Citation: No detectable trend in mid-latitude cold extremes during the recent period of Arctic amplification
J. Cohen, L. Agel, M. Barlow, D. Entekhabi
Communications Earth & Environment 4 (341) 2023