1/ 🌊New paper out in @pnas.org!
We show that human-induced global warming is responsible for a 3-fold increase in marine heatwave (MHW) persistence and a 1°C rise in their intensity since 1940.
Let’s dive in.
#MarineHeatwaves #ClimateChange
https://doi.org/10.1073/pnas.2413505122
We show that human-induced global warming is responsible for a 3-fold increase in marine heatwave (MHW) persistence and a 1°C rise in their intensity since 1940.
Let’s dive in.
#MarineHeatwaves #ClimateChange
https://doi.org/10.1073/pnas.2413505122
Comments
They’re increasing in frequency, intensity, and duration—posing threats to ecosystems like coral reefs, kelp forests, and seagrasses.
But: How much of this is due to global warming?
Using ERA5 SST data (1940–2023), we constructed a counterfactual climate—a version of the ocean without long-term global warming, but keeping natural variability (ENSO, etc.).
This allows a clean attribution.
Since 1940, the average number of MHW days per year has gone from 15 → 49.
In the counterfactual climate? Still ~16 days/year.
=> 34 extra MHW days/year due to warming. That’s a 3x increase.
Global warming accounts for a 1°C rise in maximum MHW temperature anomalies since 1940.
In some regions (like the Mediterranean), the contribution exceeds 2°C.
Let that sink in.
In the tropics: MHWs have become more persistent, not necessarily hotter.
In high-latitude boundary currents: MHWs have grown more intense.
Some areas (e.g. Med Sea, Baltic) show strong increases in both.