Abstract
The Blob was a marine heat wave in the Northeast Pacific from 2013 to
2016. While the upper ocean temperature in the Blob has been well
described, the impacts on marine biogeochemistry have not been fully
studied. Here, we characterize and develop understanding of Eastern
North Pacific upper ocean biogeochemical properties during the Winter of
2013-14 using in situ observations, an observation-based product, and
reconstructions from a collection of ocean models. We find that the Blob
is associated with significant upper ocean biogeochemical anomalies: a
5% increase in aragonite saturation state (temporary reprieve of ocean
acidification) and a 3% decrease in oxygen concentration (enhanced
deoxygenation). Anomalous advection and mixing drives the aragonite
saturation anomaly, while anomalous heating and air-sea gas exchange
drive the oxygen anomaly. Marine heatwaves do not necessarily serve as
an analogue for future change as they may enhance or mitigate long-term
trends.