Ocean’s Cool Surface: Key to More Carbon Absorption

New research reveals that subtle temperature differences at the ocean's surface enhance the absorption of carbon dioxide (CO2). Scientists studied the "ocean skin," a layer less than 2 mm deep that is slightly cooler than the surrounding water. This phenomenon, while theorized, had never been observed in open sea conditions.

The study, conducted by researchers from the University of Exeter's Penryn Campus in Cornwall, utilized precise measurements to confirm that the cooler temperature of the ocean skin aids in carbon absorption. Published in Nature Geoscience, the research is titled "Enhanced ocean CO2 uptake due to near surface temperature gradients."

Conducted in the Atlantic Ocean, the findings suggest it absorbs approximately 7% more CO2 annually than previously estimated. While this increase may seem small, it is equivalent to one and a half times the carbon captured by the Amazon rainforest each year when considered globally.

The global ocean absorbs about a quarter of humanity's carbon emissions, playing a crucial role in slowing climate change, although it also faces ecological harm. Dr. Daniel Ford, the lead author, noted that this research enhances understanding of CO2 fluxes at the ocean surface.

With the COP29 climate change conference approaching, the findings emphasize the importance of oceans and could improve global carbon assessments used for emissions reductions. The research team incorporated these findings into this year’s Global Carbon Budget assessment.

Data was collected through ship observations supported by the European Space Agency, using CO2 flux systems to measure variations in CO2 levels in the air above the ocean. Previously, air-sea CO2 flux estimates often overlooked the significance of near-surface temperature differences.

Dr. Gavin Tilstone from Plymouth Marine Laboratory (PML) highlighted the intricate nature of the ocean's water column and its influence on CO2 absorption. Understanding these mechanisms is vital for refining climate models and predictions, underscoring the ocean's critical role in regulating the planet's carbon cycle.