Climate Crisis Fingerprint on US March Weather Extremes, Experts Warn
The United States is grappling with a striking and diverse array of weather extremes this March, from flooding rains in Hawaii to rare snow in Alabama and a severe heatwave scorching the west coast. This patchwork of conditions is raising urgent questions about the role of the climate crisis in amplifying these patterns, with experts suggesting that the intensity of events, particularly on the warm side, bears a clear fingerprint of human-induced global warming.
Unpredictable March Weather and the Jet Stream's Role
March has long been known for its unpredictability, especially in regions like the north-east, where temperature swings are common. Jon Nese, associate head of the department of meteorology and atmospheric science at Penn State, noted that the weather has behaved as expected, with warm days followed by sharp cold snaps and snow. In New York, Daniel Bader, a program manager at the Consortium for Climate Risk in the Urban Northeast at Columbia's climate school, described a dramatic swing where temperatures in Central Park hit 80 degrees, only to see snowflakes two days later.
The key driver behind these simultaneous extremes is the jet stream, a fast-moving air current high in the atmosphere that can become wavy, creating ridges of warm air in one region and troughs of cold air in another. Nese explained that the heatwave in the west and the cold in the east are related phenomena, influenced by these atmospheric patterns. Bader echoed this, highlighting that seasonal shifts in temperature gradients affect the jet stream's behavior, contributing to extreme events.
Record-Breaking Heatwave in the West
While March extremes are not new, this year's events indicate a ramping up in severity, particularly with heat. The western US has seen frequent record-breaking heat in recent years, and this past week was no exception. California, Nevada, and Arizona were under heat warnings, with the National Weather Service describing conditions in the Los Angeles area as "extremely rare heat for March." Palm Springs reached a high of 107°F on Thursday, with heat alerts remaining in effect.
A rapid analysis released Friday found that the heatwave scorching the west would have been "virtually impossible" without the climate crisis. Global warming, primarily from burning fossil fuels, has made such heatwaves four times more likely over the last decade. Nese remarked that the warmth in the west is very unusual, potentially setting numerous high-temperature records, some of which may beat April records. Bader was even more direct, calling the conditions "really unprecedented" and predicting that the warmest March temperature ever recorded in the US might fall.
Broader Trends and Climate Connections
Even isolated anomalies, like snow in Alabama, underscore the broader variability. Several states, including Wisconsin, Minnesota, and Michigan, saw significant snowfall, and a potent storm system left half a million homes and businesses without power from the midwest to the east coast. Nese noted that snow in Alabama in March is pretty unusual, though the overlap with the climate crisis is complex and still under study.
However, there is clearer consensus on heat events. Nese added that it's reasonable to say this western heatwave has a climate change fingerprint, while Bader emphasized that extreme heat events are becoming more frequent and intense due to global warming. He also explained that a warmer atmosphere can hold more moisture, potentially leading to heavier precipitation and intensifying rainfall.
Preparedness and Future Outlook
As the planet continues to heat up, record-breaking heatwaves are greatly outpacing cold weather events. This summer is expected to be among the hottest on record, driven by the climate crisis and the potential development of a strong El Niño. With extremes becoming more unpredictable, experts stress the importance of preparedness. Bader warned that these events are constant reminders of vulnerability to weather and climate extremes, urging action to minimize impacts. This comes amid concerns about funding cuts to agencies like the Federal Emergency Management Agency, which could erode US capacity to respond to natural disasters.
In summary, the US March weather extremes highlight a growing trend where the climate crisis intensifies familiar patterns, making preparedness and mitigation efforts more critical than ever.
