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Research Area

Monitoring & Modeling

Ocean acidification monitoring and modeling are essential to assess ocean conditions and link ocean chemistry to impacts to marine life and the people who depend on healthy ecosystems.

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Monitoring "The Big Four"

Learn about what we measure and why.

pH

When the ocean absorbs carbon dioxide, chemical reactions create hydrogen ions that act like free agents, able to react with other compounds. Two ways we track ocean acidification are through pH and total alkalinity (TA). pH is a measure of how many free hydrogen ions are in the seawater. The more carbon dioxide in the ocean, the more these free agents are created, causing lower pH (more acidic).

pCO2

The partial pressure of CO2 (pCO2) tells us how much carbon dioxide is in seawater. This information helps us understand ocean carbonate chemistry and biological productivity in the region. pCO2 increases when the ocean absorbs more CO2 from the atmosphere with elevated emissions.

TA

Alkalinity is the ocean’s buffering system against increasing acidity. Total alkalinity is a measure of the concentration of buffering molecules like carbonate and bicarbonate in the seawater that can neutralize acid.

DIC

Dissolved inorganic carbon (DIC) tells us how much non-biological carbon is in seawater. Inorganic carbon comes in three main forms that we measure for DIC: carbon dioxide (CO2), bicarbonate (HCO3-), and carbonate (CO32-). Understanding DIC can help us determine the balance of carbonate forms in the ocean and the likelihood of ocean acidification.

Buoys & Moorings

We currently have 15 OAP-supported buoys in coastal, open-ocean, and coral reef waters and one in the Great Lakes.

There are currently 15 OAP-supported buoys in coastal, open-ocean and coral reef waters and one in the Great Lakes that contribute to NOAA's Ocean Acidification Monitoring Program.

  • Currently, there are several types of floating platforms to which instruments can be added in order to measure various ocean characteristics - buoys or moorings, wave gliders, and saildrones.
  • Buoys are moored, allowing them to remain stationary and for scientists to get measurements from the same place over time. The time series created from these measurements are key to understanding how ocean chemistry is changing over time.
  • There are also buoys moored in the open-ocean and near coral reef ecosystems to monitor the changes in the carbonate chemistry in these ecosystems. The MAPCO2 sensors on these buoys measure pCO2 every three hours.
Access Buoy Data

Ship Surveys

Ocean acidification rsearch cruises are a way to collect information about a certain ecosystem or area of interest.

Anchors aweigh on ocean acidification research cruises

For decades, scientists have learned about physical, chemical and biological properties of the ocean and coasts by observations made at sea. Measurements taken during research cruises can be used to validate data taken by autonomous instruments. These research cruises serve as anchors to bring together researchers from the region and to serve as high-quality data benchmarks for other ocean monitoring in the area. 

Coastal OA Cruises
The CTD
One instrument that is paramount on research cruises is a conductivity, temperature, and depth sensor (CTD). CTDs measure fundamental water properties that are essential in water analysis, namely temperature, salinity, and depth. The sensor often goes in the water on a rosette, which also carries Niskin bottles used to collect water samples from various depths in the water column.
What we can learn from the CTD...
Numerous chemical and biological properties can be measured from water collected in the Niskin bottles. These properties include different parameters of the carbonate system used to assess ocean acidification, but also oxygen, nutrients, phytoplankton and more. This approach has the potential to co-locate several types of chemical, physical and biological information that can be used to elucidate processes and ocean acidification effects.

Ships of Opportunity

Partnering with the Private Sector

Ships of Opportunity (SOPs) or Volunteer Observing Ships (VOSs) are vessels at sea for reasons other than ocean acidification , such as commercial cargo ships or ferries.

The owners of these vessels allow scientific instrumentation that measures ocean acidification parameters to be installed and collect data while the ship is underway. This allows data on ocean chemistry to be collected in many remote areas of the world’s ocean, such as high latitude waters, long distances from land (e.g. mid-basin waters), and places not easily accessible by research cruises. These partnerships have greatly increased the spatial coverage of ocean acidification monitoring world-wide. To learn more, check out the Ships of Opportunity programs established by the NOAA Pacific Marine Environmental Laboratory (PMEL) and the NOAA Atlantic Oceanographic Marine Laboratory (AOML).

See our funded projects in monitoring.

NOAA ship in background during the West Coast Ocean Acidification research cruise with a mooring measuring ocean chemistry in the foreground. Credit: NOAA
Optimizing the ocean acidification observing system in California
  • PI(s): Christopher Edwards, University of California, Santa Cruz
  • Fiscal Year Funded: 2019, 2020, 2021
This project specifically investigates how the observing network is contributing to forecasting models using these complex tools to estimate ocean acidification conditions throughout the central California Current System...
Project Summary >
Three bottles with labels of certified reference materials used for ocean acidification chemistry research. Credit: Scripps Institution of Oceanography
Building capacity for seawater certified reference materials
  • PI(s): Denis Pierrot, NOAA Atlantic Oceanic and Meteorological Laboratory; Katelyn Schockman, University of Miami/CIMAS
  • Fiscal Year Funded: 2024, 2025, 2026
This project will build a reference material (RM) production facility at NOAA’s Atlantic Oceanic and Meteorological Laboratory (AOML), with the capability to produce RMs for use by NOAA laboratories and..
Project Summary >
Map of SOCAT (v1.5) surface fCO2 values released on September 14, 2011. Credit: NOAA PMEL
Optimizing Global Observations of Carbon Dioxide in the Surface Ocean Using Machine Learning
  • PI(s): Galen A. McKinley, Columbia University
  • Fiscal Year Funded: 2023, 2024, 2025
This work will assess how we can optimize observing resources from the global fleet to support improved, efficient, and cost-effective monitoring of the ocean carbon sink and minimize uncertainty. Researchers..
Project Summary >

Wave Gliders

The Carbon Wave Glider

Scientists at the NOAA Pacific Marine Environmental Laboratory (PMEL) work with engineers at Liquid Robotics, Inc. to optimize a Carbon Wave Glider.

This wave glider can navigate via satellite from land. Carbon Wave Gliders can be outfitted with pCO2, pH, oxygen, temperature and salinity sensors. Gliders takes measurements as it moves through the water, expanding the spatial sampling of the area. The glider’s motion is driven by wave energy, and its sensors are powered through solar cells and batteries, when needed.

Coral Reef Monitoring

NOAA’s Coral Reef Conservation Program (CRCP) in partnership with OAP engages in a coordinated
and targeted series of field observations, moorings and ecological monitoring efforts in coral reef ecosystems.

The Coral Reef Conservation Program (CRCP) documents the dynamics of ocean acidification in coral reef systems and tracks the status and trends in ecosystem response. This effort serves as a subset of a broader CRCP initiative referred to as the National Coral Reef Monitoring Plan, which was established to support conservation of the Nation’s coral reef ecosystems.

OAP contributes to this plan through overseeing and coordinating carbonate chemistry monitoring. This monitoring includes a broadly distributed spatial water sampling campaign complemented by a more limited set of moored instruments deployed at a small subset of representative sites in both the Atlantic, Caribbean, and Pacific regions.

Coral reef carbonate chemistry monitoring is implemented by researchers at the NOAA Atlantic Oceanographic & Meteorological Laboratory (AOML) and NOAA’s Pacific Islands Fisheries Science Center (PIFSC) Coral Reef Ecosystems Division.

Benthic Surveys

Divers conduct benthic surveys to account for coral diversity and assess fish communities.

Calcification Accretion Units

Calcification Accretion Units (CAUs) assess the effects of changes in seawater carbonate chemistry on calcification (growth) and accretion in coral reefs and fleshy algae.

Monitoring Carbonate Chemistry

Carbonate chemistry monitoring determines the status of ocean acidification and its potential impacts on calcifiers like coral reefs and coralline algae.

Benthic Quadrats

Benthic quadrats are a common field tool when assesing coral cover.

CT Scans

Computerized tomography (CT) scans image the internal structure of corals.

Autonomus Reef Monitors

Deployed instruments monitor ocean conditions on reefs continuously.

Figure from: Harvey et al. 2010

Ecosystem Modeling 

Experiments on species response suggest that ocean acidification will directly affect a wide variety of organisms from calcifying shellfish and coral to fish and phytoplankton. Ecosystem models can capture the complex effects of ocean acidification on entire ecosystems.

How marine organisms respond to ocean acidification will be influenced by their reaction to chemistry change and their interactions with others species, such as their predators and prey. Scientists use ecosystem models to understand how ocean chemistry may affect entire ecosystems because they account for the complex interactions between organisms. Output from such modeling exercises can inform management of fisheries, protected species, and other important natural resources. Because ecosystem feedbacks are complex, understanding the uncertainty associated with these models is critical to effective management.

From Observations to Forecasts

Turning current observations into forecasts is the key mechanism by which adaptation plans are created.

Forecasting provides insight into a vision of the future by using models that visualize how quickly and where ocean chemistry will be changing in tandem with an understanding of how sensitive marine resources and communities are to these changes.

  • By making predictions about the future, we can better adapt and prepare for ocean acidification. Coastal forecasts for ocean acidification are currently being developed for the West Coast, Chesapeake Bay, the East Coast, Caribbean and the western Gulf of America (formerly known as Gulf of Mexico).
  • Ocean acidification hotspots are areas that are particularly vulnerable, either from a biological, economic, or cultural perspective. Identification of these hot spots in coastal waters is a priority for the Coastal Acidification Networks (CANs), fostered by the Ocean Acidification Program around the country.
  • These networks bring together scientists, decision makers, fishermen and other stakeholders to identify and answer the most important questions about acidification and its effects in the region.

NOAA scientists have played an important role in development of the J-SCOPE forecast system, used to create seasonal forecasts for the North Pacific region. These forecasts will allow fisheries managers to predict seasonal outlooks for management decisions. Click on the image to open a lightbox. 

Related Publications

See publications from our funded projects for ocean acidification monitoring.

Simultaneous onboard analysis of seawater dissolved inorganic carbon (DIC) concentration and stable isotope ratio (δ13C-DIC)
Citation: Zhentao Sun, X. L., Zhangxian Ouyang, Charles Featherstone, Eliot A. Atekwana, Najid Hussain, Wei-Jun Cai. (2024). Simultaneous onboard analysis of seawater dissolved inorganic carbon (DIC) concentration and stable isotope ratio (δ13C-DIC). Limnol Oceanogr: Methods. https://doi.org/doi: 10.1002/lom3.10642
Read Summary >
The source and accumulation of anthropogenic carbon in the U.S. East Coast
  • Xinyu Li, Zelun Wu, Zhangxian Ouyang, Wei-Jun Cai
  • Science Advances
  • August 9, 2024
Citation: Xinyu Li et al. ,The source and accumulation of anthropogenic carbon in the U.S. East Coast.Sci. Adv.10,eadl3169(2024).DOI:10.1126/sciadv.adl3169
Read Summary >
Site-Specific Multiple Stressor Assessments Based on High Frequency Surface Observations and an Earth System Model
  • Elise M. B. Olson, Jasmin G. John, John P. Dunne, Charles Stock, Elizabeth J. Drenkard, Adrienne J. Sutton
  • Earth and Space Science
  • July 22, 2024
Citation: Olson, E. M. B., John, J. G., Dunne, J. P., Stock, C., Drenkard, E. J., & Sutton, A. J. (2024). Site-specific multiple stressor assessments based on high frequency surface observations and an Earth system model. Earth and Space Science, 11, e2023EA003357. https://doi.org/10.1029/2023EA003357
Read Summary >

Get involved with ocean acidification

The NOAA Ocean Acidification Program exists to meet the ocean acidification research and monitoring needs of the U.S. See how you can get involved to serve your community and participate in cutting-edge research and education and outreach. 

Current Funding Opportunities

Bioeconomic modeling to inform Alaska fisheries management

Fishing Dock in Juneau Alaska
Image credit: Allen Shimada, NOAA NMFS

Bioeconomic models are a multidisciplinary tool that use oceanography, fisheries science and social science to assess socioeconomic impacts. Funded by the Ocean Acidification Program, researchers at the Alaska Fisheries Science Center use a bioeconomic model to study the impacts of ocean acidification on Eastern Bering Sea crab, northern rock sole and Alaska cod. The goal is to predict how ocean acidification will affect abundance yields and income generated by the fisheries. This work informs the potential economic impacts of ocean acidification and future decision making and research planning.

More about this work

Effects of ocean acidification and temperature on Alaskan crabs

Red King Crab
Image credit: David Csepp, NMFS AKFSC ABL

Long-term declines of red king crab in Bristol Bay, Alaska may be partially attributed to ocean acidification conditions. These impacts may be partially responsible for the fishery closures during the 2021–2022 and 2022–2023 seasons. Researchers found that ocean acidification negatively impacts Alaskan crabs generally by changing physiological processes, decreasing growth, increasing death rates and reducing shell thickness. Funded by the Ocean Acidification Program, scientists at the Alaska Fisheries Science Center continue to investigate the responses of early life history stages and study the potential of various Alaska crabs to acclimate to changing conditions. Results will inform models that will use the parameters studied to predict the effects of future ocean acidification on the populations of red king crab in Bristol Bay as well as on the fisheries that depend on them. Fishery managers will better be able to anticipate and manage stocks if changing ocean chemistry affects stock productivity and thus the maximum sustainable yield.

More about this work

Forecasts for Alaska Fisheries

Crab pots and fishing nets in Alaska's Dutch Harbor
Image credit: Michael Theberge

Understanding seasonal changes in ocean acidification in Alaskan waters and the potential impacts to the multi-billion-dollar fishery sector is a main priority. Through work funded by NOAA’s Ocean Acidification Program, the Pacific Marine Environmental Laboratory developed a model capable of depicting past ocean chemistry conditions for the Bering Sea and is now testing the ability of this model to forecast future conditions. This model is being used to develop an ocean acidification indicator provided to fisheries managers in the annual NOAA Eastern Bering Sea Ecosystem Status Report.

ADAPTING TO OCEAN ACIDIFICATION

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:

FORECASTING

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

Closeup of oysters cupped in someone's hands

MANAGEMENT

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

TECHNOLOGY DEVELOPMENT

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

REDUCING OUR CARBON FOOTPRINT

50 more ways to reduce your carbon footprint >

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

TAKE ACTION WITH YOUR COMMUNITY

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