The different stratospheric influence on cold-extremes in Eurasia and North America

Abstract The winter of 2013–14 had unusual weather in many parts of the world. Here we analyze the cold extremes that were widely reported in North America and the lack of cold extremes in western Europe. We perform a statistical analysis of cold extremes at two representative stations in these areas: Chicago, Illinois, and De Bilt, the Netherlands. This shows that the lowest minimum temperature of the winter was not very unusual in Chicago, even in the current warmer climate. Around 1950 it would have been completely normal. The same holds for multiday cold periods. Only the whole winter temperature was unusual, with a return time larger than 25 years. In the Netherlands, the opposite holds: the absence of any cold waves was highly unusual even now, and would have been extremely improbable halfway through the previous century. These results are representative of other stations in the regions. The difference is due to the skewness of the temperature distribution. In both locations, cold extremes are more likely than equally large warm extremes in winter. Severe cold outbreaks and cold winters, like the winter of 2013–14 in the Great Lakes area, are therefore not evidence against global warming: they will keep on occurring, even if they become less frequent. The absence of cold weather as observed in the Netherlands is a strong signal of a warming trend, as this would have been statistically extremely improbable in the 1950s.

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Opposing Trends of Winter Cold Extremes over Eastern Eurasia and North America under Recent Arctic Warming

Advances in Atmospheric Sciences ◽

10.1007/s00376-020-0070-2 ◽

2020 ◽

Vol 37 (12) ◽

pp. 1417-1434

Author(s):

Shuangmei Ma ◽

Congwen Zhu

Keyword(s):

North America ◽

Arctic Warming ◽

Winter Cold ◽

Cold Extremes

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Reduced Risk of North American Cold Extremes due to Continued Arctic Sea Ice Loss

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-14-00185.1 ◽

2015 ◽

Vol 96 (9) ◽

pp. 1489-1503 ◽

Cited By ~ 81

Author(s):

James A. Screen ◽

Clara Deser ◽

Lantao Sun

Keyword(s):

North America ◽

Sea Ice ◽

Greenhouse Gases ◽

North American ◽

Arctic Sea Ice ◽

First Century ◽

Arctic Sea ◽

Twenty First Century ◽

Arctic Sea Ice Loss ◽

Cold Extremes

Abstract In early January 2014, an Arctic air outbreak brought extreme cold and heavy snowfall to central and eastern North America, causing widespread disruption and monetary losses. The media extensively reported the cold snap, including debate on whether human-induced climate change was partly responsible. Related to this, one particular hypothesis garnered considerable attention: that rapid Arctic sea ice loss may be increasing the risk of cold extremes in the midlatitudes. Here we use large ensembles of model simulations to explore how the risk of North American daily cold extremes is anticipated to change in the future, in response to increases in greenhouse gases and the component of that response solely due to Arctic sea ice loss. Specifically, we examine the changing probability of daily cold extremes as (un)common as the 7 January 2014 event. Projected increases in greenhouse gases decrease the likelihood of North American cold extremes in the future. Days as cold or colder than 7 January 2014 are still projected to occur in the mid-twenty-first century (2030–49), albeit less frequently than in the late twentieth century (1980–99). However, such events will cease to occur by the late twenty-first century (2080–99), assuming greenhouse gas emissions continue unabated. Continued Arctic sea ice loss is a major driver of decreased—not increased—North America cold extremes. Projected Arctic sea ice loss alone reduces the odds of such an event by one-quarter to one-third by the mid-twenty-first century, and to zero (or near zero) by the late twenty-first century.

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