Recent research indicates that minor variations in ocean surface temperatures enable increased absorption of carbon dioxide (CO₂).
It has been understood by researchers that the ocean’s surface layer, just 0.01 mm thick and cooler than the water below it, should enhance carbon dioxide uptake from the atmosphere.
This is due to the fact that cooler water absorbs CO₂ more effectively. The concentration of the gas between this surface layer and the water just 2 mm beneath it governs the exchange of gas between the ocean and the atmosphere.
Although theoretical and laboratory studies have predicted that this temperature difference would boost the amount of CO₂ absorbed, it had not been successfully recorded in a natural marine environment until now.
The recent study led by researchers from the University of Exeter’s Penryn Campus in Cornwall employed precise measurements to verify that the ocean’s surface temperature indeed facilitates carbon absorption.
Conducted in the Atlantic Ocean, the results indicate that this body of water absorbs approximately 7% more CO₂ per year than previously estimated. While this may seem minor, when considered on a global scale, it is equivalent to one and a half times the carbon captured through annual growth in the Amazon rainforest.
The world’s oceans take in around a quarter of humanity’s carbon emissions, mitigating climate change while simultaneously adversely affecting marine ecosystems. These new findings enhance our understanding of these dynamics.
Lead researcher Dr. Daniel Ford from the University of Exeter stated, “Our results provide measurements that validate our theoretical knowledge regarding CO₂ exchanges at the ocean surface.”
He added, “With the upcoming COP29 climate conference next month, this research emphasizes the oceans’ critical role, and it should assist in refining the global carbon evaluations that inform emission reduction strategies.”
The team has included these advancements in their data submission for this year’s Global Carbon Budget evaluation.
The ship observations, gathered from two projects supported by the European Space Agency, utilized CO₂ flux systems to measure the tiny variances in CO₂ levels in the air moving toward and away from the ocean’s surface, alongside high-resolution temperature readings.
Prior to this, global assessments of air-sea CO₂ exchanges generally overlooked the significance of temperature differences in the near-surface layer.
Dr. Ian Ashton, also from the University of Exeter, remarked, “This work represents the culmination of many years of collaboration among an international team of scientists. The European Space Agency’s contribution to science was vital in creating such a thorough measurement campaign across an entire ocean.”
Dr. Gavin Tilstone from Plymouth Marine Laboratory (PML) pointed out, “This finding reveals the complexity of the ocean’s water column structure and its impact on CO₂ absorption from the atmosphere. Understanding these delicate mechanisms is essential as we enhance our climate models and predictions, emphasizing the ocean’s crucial role in regulating the planet’s carbon cycle and climate.”
The study involved international collaborators, including sea temperature measurement specialists from the European Space Agency and the University of Southampton.
Funding for this research came from the European Space Agency, Horizon Europe, and the Natural Environment Research Council.
The ship surveys were part of the Atlantic Meridional Transect (AMT) project led by PML.
The findings were published in the journal Nature Geoscience under the title: “Enhanced ocean CO₂ uptake due to near-surface temperature gradients.”
