Understanding Extreme Weather in a Changing Climate

ClimaMeter is an experimental rapid framework for understanding extreme weather events in a changing climate based on looking at similar past weather situations. Find out more here and follow us on X

Storm Ingunn mostly strengthened by human-driven climate change 

The January 2024 Storm Ingunn, which struck Norway, exhibited unprecedented intensity, marked by record-breaking winds and a rapid deepening of pressure, resembling an explosive cyclone. The storm, considered a unique event, was largely fueled by human-driven climate change, as indicated by a ClimaMeter analysis comparing present-day storms with historical data. Findings reveal that storms similar to Ingunn are now up to 3°C warmer, up to 10mm/day rainier, and up to 10 km/h windier due to climate change, with notable impacts observed in urban areas like Tromsø, Trondheim, and Bergen. While natural climate variability, such as the Atlantic Multidecadal Oscillation, may have played a partial role, the primary driver behind the intensified characteristics of Storm Ingunn appears to be human-induced climate change, highlighting the increasing influence of anthropogenic factors on extreme weather events.

The ClimaMeter study's conclusions align with broader trends indicating a correlation between rising temperatures and the heightened intensity of extratropical storms, emphasizing the tangible impacts of climate change, even in traditionally colder regions like Norway. This underscores the need for comprehensive climate action to mitigate the escalating risks associated with extreme weather events, including storms, which are projected to become more severe in a warming climate. 

Image: Satellite: Meteosat-10 Product: Airmass (EUMETSAT) Instrument: SEVIRI.

Early February 2024 California Floods likely influenced mostly by human-driven climate change

On February 1, 2024, the first of two atmospheric rivers unleashed significant snowfall, accompanied by strong winds and persistent rainfall across California. Flood advisories affected over 20 million people in major cities, prompting flash flood concerns. Southern California faced relentless rain, leading to the closure of key routes and water rescues. Long Beach experienced severe flooding, with videos depicting submerged roads and rescued vehicles. The storm then shifted to San Diego, causing minor disruptions. A subsequent atmospheric river is expected to impact the region, extending rainy conditions into February.

The ClimaMeter analysis compares events similar to the February 2024 California Floods in the present (2001–2023) with the past (1979–2001). Findings show increased precipitation intensity and wind speed, primarily attributed to human-driven climate change. In particular, we find that the early February California floods are up to 14 mm/day (up to 15%) wetter and up to 8 km/h windier over the Pacific coast in the present than they have been in the past. Natural climate variability, such as the Atlantic Multidecadal Oscillation, plays a modest role. The conclusion emphasizes the urgency for cities to adapt to evolving weather patterns influenced by climate change.

Image:  Ocean Beach (San Francisco), Tweet by Max Gorden

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