From 2013–2016, an exceptional California drought coincided with unprecedented northeast Pacific marine heatwaves, leading to significant social-economical-ecological impacts—including a roughly $170 million economic loss from the Dungeness crab fishery closure. And now a new study published in Geophysical Research Letters, partially funded by CPO’s Modeling, Analysis, Predictions and Projections (MAPP) program, found that under global warming, co-occurring extreme warm northeast Pacific ocean and dry California conditions will become dramatically more frequent by the end of the 21st century.
The increasing frequency of these compound extremes is strongly driven by human-caused warming and drying trends, results show. If these trends are removed, co-occurrence between Gulf of Alaska marine heatwaves and California drought will increase, but co-occurrence of California Current marine heatwaves and California drought remains unchanged relative to cases with no warming. The authors note that understanding changes not just in extremes but in their co-occurrence and projecting their frequency in the future is critical for societies to prepare for and adapt to climate change.