Recent research is reshaping long-held assumptions about the ocean’s role in carbon cycling, highlighting the critical importance of high-frequency monitoring. Two new studies focused on the California Current Ecosystem reveal that nearshore and offshore waters behave in unexpected ways when it comes to absorbing and releasing carbon dioxide (CO₂), particularly during climate events like El Niño and marine heatwaves.
For decades, scientists have relied on sparse, monthly measurements to estimate ocean-atmosphere CO₂ exchange. But data collected every three hours from a pair of NOAA-funded buoys off Southern California suggest these traditional methods may significantly misrepresent whether a region acts as a carbon source or sink.
The buoys, equipped with advanced sensors by NOAA’s Pacific Marine Environmental Laboratory and deployed by Scripps Institution of Oceanography – transmit near-real-time measurements of ocean chemistry. This high-resolution data has provided researchers with unprecedented insights into how dynamic the ocean’s carbon uptake and release processes truly are.
One study, led by Helena Frazão and published in Journal of Geophysical Research: Oceans, found that during the 2015–2016 El Niño marine heatwave, the open ocean site (CCE1) – typically a CO₂ sink – became a source, while the nearshore site (CCE2), normally a source due to strong upwelling, flipped to a sink.
A second study, led by graduate student Ruiming Song and published in Geophysical Research Letters, focused on the nearshore buoy (CCE2) from 2011–2020. It found that short-term events – especially those involving high winds and strong upwelling – significantly increase CO₂ release to the atmosphere. When these events are averaged out in monthly data, the region appears to be a net sink. In reality, it is a net source.
“These findings challenge conventional assumptions about carbon cycling in coastal upwelling systems,” said Adrienne Sutton, co-author on both studies. “Frequent, high-resolution observations are revealing a far more complex and variable picture of ocean carbon flux – one that has major implications for regional carbon budgets and climate forecasting.”
As the industry looks toward scalable solutions for climate resilience and carbon management, these studies underscore the need for continuous, high-frequency monitoring to better inform models, forecasts, and mitigation strategies in dynamic coastal environments.
To learn more about NOAA Research in the California Current Ecosystem, click here.