Extreme cold events follow ocean circulation strength in a near-linear way, except during abrupt climate shifts.

During the last ice age, the climate suffered abrupt shifts between cold periods called stadials and warmer periods called interstadials. Scientists want to know how extreme cold snaps changed during these sudden flips. The researchers analyzed data from a CCSM4CCSM4A climate model that simulates Earth's atmosphere, oceans, and other systems. simulation of Last Glacial Maximum conditions. They used statistical models called Generalized Extreme Value distributions to track extreme cold air surface temperatures across different regions. They connected these cold extremes to the strength of the Atlantic Meridional Overturning Circulation, or AMOC, a key system of ocean currents. They found that within the cold and warm states, extreme temperature patterns changed almost linearly with AMOC strengthAMOC strengthThe intensity of the Atlantic Meridional Overturning Circulation, a key ocean current system.. However, sudden jumps or nonlinear swings occurred right at the transitions. Physical processes like expanding sea ice and changing ocean currents shifted the magnitude and variability of these cold events. Mapping extremes to AMOC strength helps scientists compare different climate models and states.

Why it matters

This helps climate scientists understand how extreme cold behaves during rapid climate changes, which is crucial for predicting future climate risks and comparing different climate models. It affects how we interpret historical climate data and prepare for potential shifts in weather patterns.

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