The December 2022 North American Winter Storm mostly weakened by human-driven climate change

Press Summary (First published 2023/10/05, Updated on 2023/11/22)

• Low pressure systems similar to that producing the December 2022 North American Winter Storm are locally 0-5 °C warmer and 0-10mm/day dryer in the present than they have been in the past.

• The December 2022 North American Winter Storm was a largely unique event.

• We mostly ascribe changes in the intensity of the  December 2022 North American Winter Storm to human driven climate change and natural climate variability likely played a modest role.

Event Description

In late December 2022, a historic low pressure area wreaked havoc across the United States and parts of Canada. From December 21 to 26, this unprecedented storm unleashed blizzards, high winds, heavy snowfall, and record-breaking cold temperatures. The affected regions included Minnesota, Iowa, Wisconsin, Michigan, Ohio, Pennsylvania, New York, and Ontario, with some areas enduring nearly two days of zero-visibility blizzard conditions. The cold wave reached as far south as Miami, Florida, causing wind chill alerts for 110 million people across 36 U.S. states.Tragically, this storm and the accompanying cold wave claimed the lives of at least 100 people. An additional six deaths were attributed to a smaller storm in the Pacific Northwest. The Buffalo area in New York was particularly hard-hit, with lake-effect snowfall exceeding 56 inches over five days, leading to 41 fatalities. The storm also caused extensive vehicle pileups, road closures, and flight cancellations. Buffalo Niagara International Airport was shut down for five days, and rail services were severely disrupted. Power outages affected approximately 6.3 million households in the U.S. and 1.1 million in Canada. The storm was unofficially named Winter Storm Elliott by The Weather Channel and was described by the National Weather Service as a "once-in-a-generation storm" for Buffalo. NOAA's Weather Prediction Center deemed it a "historic arctic outbreak," and it was widely referred to as the "Blizzard of the Century." The storm's meteorological history began on December 21, strengthening over the Northern Plains and intensifying into a bomb cyclone. Blizzard conditions were reported in several states, with snowfall, high winds, and damage to buildings. The storm's pressure plummeted, creating a massive wind field and bitterly cold air.In the days that followed, blizzard conditions persisted in various areas, including Detroit, Grand Rapids, and Cincinnati. Buffalo, New York, experienced record lake-effect snowfall, with snow accumulating to over 56 inches in some places. The city endured prolonged periods of zero visibility and complete whiteout conditions. The storm also impacted other parts of the northeastern U.S., resulting in significant snowfall and high tides. Ocean-effect snow hit Cape Cod, and in Canada, cities like Kingston, Prince Edward County, and Fort Erie experienced blizzard conditions and record-breaking wind gusts.

The Surface Pressure Anomalies reveal a weather pattern characterized by a low-pressure systems over Labrador Peninsula. This unusual atmospheric setup led to a significant influx of cold air directed toward the Great Lake region and Eastern US. Temperature Anomalies indicate that most of the area covered by the analysis experienced extremely cold anomalies reaching up to -20°C in certain areas. Precipitation Data show that the Eastern Coast of Canada and USA and Quebec received large amounts of precipitation, mostly in the form of snow. The storm also caused strong winds as shown in Windspeed Data. 

Climate and Data Background for the Analysis

The IPCC AR6 WG1 report discusses the significant impact of climate change on the frequency and intensity of cold outbreaks in North America. According to the IPCC, as the region has experienced an overall increase in average temperatures, a notable shift has occurred in the occurrence of temperature extremes. Specifically, extreme high-temperature records are now being set more frequently than extreme cold records. This shift is attributed to antrhopogenic climate change, which has fundamentally altered the temperature dynamics of the continent. The warming trend is not uniform across North America but exhibits pronounced polar amplification, particularly in high latitudes and during winter months.  One of the outcomes of this temperature shift is the reduction in the severity of extreme cold events. The IPCC also highlights that this change is not limited to temperature records alone. It has a broader impact on the region's climate dynamics, including alterations in precipitation patterns, snowpack, and other related climatic variables. These shifts in climate variables have cascading effects on various aspects of North America's environment, such as changes in snowpack and glacier extent, reductions in sea and lake ice. This shift carries profound implications for various sectors, from agriculture to infrastructure planning, as North America adapts to this changing climate landscape.

Our analysis approach rests on looking for weather situations similar to those of the event of interest having been observed in the past. For the December 2022 North American Winter Storm, we have low confidence in the robustness of our approach given the available climate data, as the event is largely unique in the data record.

ClimaMeter Analysis

We analyse here (see Methodology for more details) how events similar to the low pressure systems leading to the December 2022 North American cold spell have changed in the present (2001–2022) compared to what they would have looked like if they had occurred in the past (1979–2000) in the region [-110°E -45°E 30°N 66°N]. The Surface Pressure Changes show that low pressure systems have not significantly changed their intensity compared to the past except in some limited areas. Temperature Changes show that similar events produce milder (0-5 °C) temperatures in the present than in the past. Considering the affected urban areas, Montreal, New York and Detroit see about the same temperature in the present than in the past. Montreal tends also to receive more snow or freezing rain in the present than in the past, while Detroit and New-York experience significantly dryer conditions.  We also find that Similar Past Events are less frequent now in December and January.

Finally, we find that sources of natural climate variability, notably the Pacific Decadal Oscillation, may have influenced the event. This suggests that the changes we see in the event compared to the past may be due to human driven climate change, with a secondary contribution from natural variability.

Conclusion

Based on the above, we conclude that low pressure patterns similar to that causing the December 2022 North American Winter Storm have become 0-5 °C locally warmer in the present than in the past. We interpret the December 2022 North American Winter Storm as a largely unique event for which natural climate variability played a modest role.

Contact Authors

Davide Faranda, IPSL-CNRS, France  📨davide.faranda@lsce.ipsl.fr  🗣️French, Italian, English

Tommaso Alberti, INGV, Italy  📨tommaso.alberti@ingv.it  🗣️Italian, English