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New Study Reveals Ocean Temperature’s Role in Carbon Dioxide Absorption
Recent research indicates that slight variations in ocean surface temperatures significantly enhance the absorption of carbon dioxide (COâ‚‚).
For years, scientists have hypothesized that the ocean’s surface layer, known as the “ocean skin,” which is a mere 0.01 mm thick and usually cooler than the water just below it, plays a critical role in COâ‚‚ absorption. This phenomenon is due to the fact that cooler water can absorb more COâ‚‚, with the gas concentration differences between this top layer and the water slightly deeper (about 2 mm) controlling the gas exchange between the ocean and the atmosphere.
The implications of theoretical and laboratory studies suggested a marked increase in CO₂ absorption attributable to these temperature differences, yet observational evidence from the ocean had been lacking—until now.
The ground-breaking study, conducted by researchers at the University of Exeter’s Penryn Campus in Cornwall, employed high-precision measurements in the Atlantic Ocean to validate the theory that the temperature of the ocean skin promotes greater carbon absorption.
The results indicate that the oceans absorb approximately 7% more COâ‚‚ annually than previously estimated. While this may seem minimal, when considered on a global scale, this increased absorption equals 1.5 times the carbon captured through yearly growth in the Amazon rainforest.
Globally, oceans play a crucial role in absorbing around 25% of human-generated carbon emissions, which helps mitigate climate change, even as these processes can also have detrimental effects on marine ecosystems. The latest findings contribute significantly to our understanding of these dynamics.
“Our results provide vital measurements that bolster our theoretical framework regarding COâ‚‚ fluxes at the ocean surface,” stated Dr. Daniel Ford, the study’s lead author from the University of Exeter. “As the COP29 climate conference approaches, it is essential to recognize the critical function of oceans, and our research should aid in refining global carbon assessments aimed at emission reductions.”
This advancement has been incorporated into the team’s contribution to this year’s Global Carbon Budget report.
The research involved observations made aboard ships as part of two European Space Agency initiatives, utilizing COâ‚‚ flux systems to detect minute fluctuations in COâ‚‚ levels in the atmosphere as they approached and departed from the ocean surface, alongside detailed temperature measurements.
Historically, estimates for global air-sea COâ‚‚ exchanges have generally overlooked the significance of temperature differences in the near-surface layer.
Dr. Ian Ashton, also part of the University of Exeter team, remarked, “This study is the outcome of extensive collaborative efforts from an international team of scientists. The European Space Agency’s backing was pivotal in facilitating such comprehensive measurement campaigns across the ocean.”
Dr. Gavin Tilstone from Plymouth Marine Laboratory emphasized, “This finding underscores the complexity of the ocean’s stratification and how it actively influences atmospheric COâ‚‚ draw-down. Grasping these intricate mechanisms is essential for improving our climate models and forecasts. It highlights the ocean’s crucial role in managing the global carbon cycle and climate.”
The collaboration also included sea temperature monitoring specialists from the European Space Agency and the University of Southampton, with funding from the European Space Agency, Horizon Europe, and the Natural Environment Research Council. The ship-based research was part of the Atlantic Meridional Transect (AMT) project led by Plymouth Marine Laboratory.
The findings were published in the journal Nature Geoscience under the title: “Enhanced ocean COâ‚‚ uptake due to near surface temperature gradients.”
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