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Air-sea CO2 flux in the Gulf of Mexico from observations and multiple machine-learning data products

Citation: Zelun Wu, Hongjie Wang, Enhui Liao, Chuanmin Hu, Kelsea Edwing, Xiao-Hai Yan, Wei-Jun Cai, Air-sea CO2 flux in the Gulf of Mexico from observations and multiple machine-learning data products, Progress in Oceanography, Volume 223, 2024,103244, ISSN 0079-6611,

Quantifying air-sea carbon dioxide (CO2) flux from observations is subject to uncertainties due to missing data, uneven data distribution, and a relatively short observation period in the Gulf of Mexico (GOM). Despite the publication of multiple seawater partial pressure of CO2 (pCO2sw) products, their reliabilities in the GOM have been relatively understudied. We compare the Surface Ocean CO₂ Atlas (SOCAT) observation-based synthesis with eight regional and global machine-learning pCO2sw data products in the GOM. SOCAT reveals significant spatial and seasonal variations in pCO2sw in the GOM owing to complex local nonthermal (physical and biological) dynamics, particularly in the Louisiana Shelf (LAS) and Western Florida Shelf (WFS). The regional pCO2sw data product outperforms the global products in capturing small-scale pCO2sw variations. When averaging climatology across the entire northern GOM, the spatial heterogeneity of pCO2sw and CO2 flux resulting from local nonthermal processes tends to counterbalance across the entire GOM in all pCO2sw data products. Consequently, the regional data product and the ensemble mean of seven global products yield pCO2sw climatology that closely aligns with the SOCAT observations with a small difference (< ±3 µatm). During the overlapping period from 2003 to 2017 (15 years), the average flux from the eight products indicates that the entire GOM is CO2-neutral, with an ocean uptake flux of 0.08 ± 0.12 mol C/m2/yr or 1.50 ± 2.25 TgC/yr, which is about 0.6 % of the global coastal ocean CO2 sink. Observations show that the pCO2sw trend also exhibits notable spatial differences, with the river plume area acting as an increasing CO2 sink and the WFS acting as an increasing CO2 source. Due to limited observations and large spatiotemporal variations, the true values of the decadal trend still have large uncertainties in the highly dynamic river plume area. In most other subregions, pCO2sw increases following atmospheric CO2. Uncertainties persist across all pCO2sw data products in simulating the decadal trend, given that the regional product displays essentially no trend (<0.5 µatm/yr), while the ensemble average of global products exhibits a trend that follows atmospheric pCO2 (∼+2.0 µatm/yr). Our findings demonstrate that existing pCO2sw data products effectively simulate the climatology of pCO2sw in the GOM, providing valuable information for CO2 flux quantification in the GOM. Future research should emphasize the development of pCO2sw data products designed to accurately predict small-scale variations and temporal shifts, while also delving into the underlying dynamics responsible for these changes.

Supported by National Oceanic and Atmospheric Administration’s Ocean Acidification Program (OAP)[NA21NOS0120096]

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The NOAA Ocean Acidification Program (OAP) works to prepare society to adapt to the consequences of ocean acidification and conserve marine ecosystems as acidification occurs. Learn more about the human connections and adaptation strategies from these efforts.

Adaptation approaches fostered by the OAP include:


Using models and research to understand the sensitivity of organisms and ecosystems to ocean acidification to make predictions about the future, allowing communities and industries to prepare


Using these models and predictions as tools to facilitate management strategies that will protect marine resources and communities from future changes


Developing innovative tools to help monitor ocean acidification and mitigate changing ocean chemistry locally


On the Road

Drive fuel-efficient vehicles or choose public transportation. Choose your bike or walk! Don't sit idle for more than 30 seconds. Keep your tires properly inflated.

With your Food Choices

Eat local- this helps cut down on production and transport! Reduce your meat and dairy. Compost to avoid food waste ending up in the landfill

With your Food Choices

Make energy-efficient choices for your appliances and lighting. Heat and cool efficiently! Change your air filters and program your thermostat, seal and insulate your home, and support clean energy sources

By Reducing Coastal Acidification

Reduce your use of fertilizers, Improve sewage treatment and run off, and Protect and restore coastal habitats

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You've taken the first step to learn more about ocean acidification - why not spread this knowledge to your community?

Every community has their unique culture, economy and ecology and what’s at stake from ocean acidification may be different depending on where you live.  As a community member, you can take a larger role in educating the public about ocean acidification. Creating awareness is the first step to taking action.  As communities gain traction, neighboring regions that share marine resources can build larger coalitions to address ocean acidification.  Here are some ideas to get started:

  1. Work with informal educators, such as aquarium outreach programs and local non-profits, to teach the public about ocean acidification. Visit our Education & Outreach page to find the newest tools!
  2. Participate in habitat restoration efforts to restore habitats that help mitigate the effects of coastal acidification
  3. Facilitate conversations with local businesses that might be affected by ocean acidification, building a plan for the future.
  4. Partner with local community efforts to mitigate the driver behind ocean acidification  – excess CO2 – such as community supported agriculture, bike & car shares and other public transportation options.
  5. Contact your regional Coastal Acidification Network (CAN) to learn how OA is affecting your region and more ideas about how you can get involved in your community
       More for Taking Community Action