Clustering to Characterize Extreme Marine Conditions for the Benthic Region of the Northeastern Pacific Continental Margin

Abstract Anthropogenic CO2 emissions lead to ocean warming, deoxygenation and acidification. Superimposed on long‐term trends are episodic extremes of temperature, oxygen, and acidity. Here we present an innovative method for assessing single and compound extremes using a high‐resolution regional model of the Northeastern Pacific Ocean. We use an unsupervised clustering approach to identify regions with similar habitat characteristics near the seafloor, define extreme thresholds seasonally using a fixed baseline (1996–2020) within each cluster, and quantify the fraction of ocean waters that exceed these thresholds for both single and compound stressors. Compound extremes (most commonly of O2 and acidification) are rare but show an increasing trend in some clusters. Potential predictability of occurrence of extremes is demonstrated by correlation with basin‐scale climate variability.