experiment on ocean acidification

Ocean Acidification in a Cup

Create a carbon dioxide–rich atmosphere in a cup and watch how it changes the water beneath it. This model of ocean-atmosphere interaction shows how carbon dioxide gas diffuses into water, causing the water to become more acidic. Ocean acidification is a change that can have big consequences. 

Video Demonstration

• Safety goggles
• An acid-base indicator such as bromothymol blue, diluted with water: 8 milliliters bromothymol blue (0.04% aqueous) to 1 liter of water (see the Teaching Tips section below for alternative acid-base indicators, including one made from cabbage juice)
• Two clear 10-oz plastic cups (the tall ones)
• Paper cups, 3-oz size (you’ll only use one in the experiment, but keep a few extras at hand just in case)
• Masking tape
• Plain white paper
• Permanent marker
• Baking soda
• White vinegar
• Two Petri dishes to use as lids for the plastic cups
• Graduated cylinder or measuring spoons
• Gram scale or measuring spoons

• Put on your safety goggles.
• Pour 1 1/2 fluid ounces (40–50 mL) of acid-base indicator solution into each of the two clear plastic cups. 
• Add 1/2 teaspoon (2 grams) of baking soda to the paper cup.
• Tape the paper cup inside one of the clear plastic cups containing the indicator solution so that the top of the paper cup is about 1/2 inch (roughly 1 centimeter) below the top of the plastic cup. Make sure the bottom of the paper cup is not touching the surface of the liquid in the plastic cup—you don’t want the paper cut to get wet. The second plastic cup containing indicator solution will be your control.
• Place both clear plastic cups onto a sheet of white paper and arrange another piece of white paper behind the cups as a backdrop (this makes it easier to see the change).

Position yourself so you are at eye level with the surface of the indicator solution and look closely. What do you see? Where is the color change taking place? 

After a few minutes have passed, you should notice a distinct color change at the surface of the liquid. As you continue to observe the reaction taking place, the liquid in other parts of the cup will also begin to change color.

This activity illustrates how the diffusion of a gas into a liquid can cause ocean acidification. It also models part of the short-term carbon cycle—specifically the interaction between our atmosphere and the ocean’s surface.

Mixing vinegar and baking soda together in the paper cup creates carbon dioxide gas ( CO 2 ). The CO 2  gas then diffuses into the liquid below. When CO 2  gas diffuses into water, the following chemical reaction takes place and results in carbonic acid (H 2 CO 3 ): 

$$\text{CO}_2 (\text{aq}) + \text{H}_2\text{O} \rightarrow \text{H}_2\text{CO}_3$$

Carbonic acid dissociates into H + and HCO 3 - . The increase in H + causes the solution to become more acidic.

Carbonic acid is a weak acid. Even so, the presence of this acid affects the pH of the solution. Thus, after a short time, the surface of the indicator solution changes color: from blue to yellow if you’re using bromothymol blue or from purple to pale pink if you’re using cabbage-juice indicator. This color change indicates a pH change caused by the diffusion of CO 2 gas into the liquid.

Outside of your paper cup, on a much larger scale, atmospheric CO 2 diffuses into the oceans.¹ Oceans are the primary regulator of atmospheric CO 2 . Human activities such as burning fossil fuels and changes in land use have increased the amount of carbon dioxide (CO 2 ) in the atmosphere from 540 gigatons of carbon (Gt C) in pre-industrial times to 800 Gt C in 2015. 

Current atmospheric CO 2  levels are greater than they have been in 800,000 years, and as a result, the fast carbon cycle is no longer in balance. From 1860 to 2009, the oceans absorbed an additional 150 Gt C from the atmosphere.

The CO 2 taken up by the oceans reduces oceanic pH through a series of chemical reactions. The first of these is the reaction you just observed: the creation of carbonic acid via the diffusion of CO 2 gas into water.²

In pre-industrial times, the pH of the oceans was close to 8.2. In 2005, it was approximately 8.1.³ While the pH of the ocean is still basic, it is more acidic than it used to be. Since the pH scale is logarithmic, this means that the oceans are 30% more acidic now than they were in pre-Industrial times.⁴

Diffusion goes both ways—from the atmosphere into a liquid and from a liquid into the atmosphere. This experiment shows passive diffusion: the CO 2 gas diffuses into the liquid. What experiment might you try in order to show that diffusion also goes the other way—from a liquid back into the atmosphere?

In March 2015, the global monthly average of the atmospheric concentration of CO 2 was around 400 parts per million (ppm), or 0.04%. It is a small amount, but it is increasing by more than 2 ppm every year due to the combustion of fossil fuels such as oil, gasoline, natural gas, and coal, as well as land-use changes such as deforestation.

Increases in the concentration of atmospheric CO 2 have led to increases in the concentration of CO 2  and other carbon-containing molecules in seawater. The CO 2 added to seawater reacts with the water molecules to form carbonic acid in a process known as ocean acidification . The oceans are absorbing about 25% of the CO 2 we release into the atmosphere each year. Additionally, as more CO 2 gas enters the atmosphere, the atmosphere gets warmer, causing global temperatures to rise.

Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher CO 2 conditions in the ocean, as they require CO 2 to live (just like plants on land). On the other hand, studies have shown that a more acidic ocean environment has a dramatic effect on some calcifying species including oysters, shellfish, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk.

Our understanding of the phenomenon explored in this Science Snack is built on the work of many scientists.

Dr. Katsuko Saruhashi was a groundbreaking Japanese geochemist responsible for two important techniques that help scientists understand the global effects of rising carbon dioxide levels. In 1957, Dr. Saruhashi was the first woman to earn a doctorate from the University of Tokyo (then called the Imperial Women’s College of Science). She went on to develop a process for accurately measuring carbon dioxide in water; this methodology, called "Saruhashi’s Table," was essential for demonstrating that global warming would not be substantially curbed by ocean water’s capacity to absorb carbon dioxide, and continues to be used globally today. She also developed methods and tools for tracking radioactive fallout across oceans, ultimately leading to the reduction of oceanic nuclear experimentation. She was the first woman elected to the Science Council of Japan in 1980, the first to win the Miyake Prize in geochemistry in 1985, and in 1981, she established the Saruhashi Prize, which continues to inspire and honor young women in the natural sciences today. You can measure the concentration of carbon dioxide in water using a different method than Dr. Saruhashi's with the Ocean Acidification in a Cup Science Snack.

Prior to trying Ocean Acidification in a Cup, learners should be familiar with acid-base indicators and know that baking soda and vinegar create CO 2 gas when mixed. This lesson dovetails with lessons on surface interactions and diffusion.

Making your cabbage-juice indicator If bromothymol blue indicator is hard to come by, or if you’d prefer not to use this chemical in your classroom, you can use cabbage-juice indicator instead. It’s easy to make: Just take a quarter of a head of purple cabbage, place it in a blender with water to cover, and blend until you get a uniform puree. Strain the resulting mixture—the purple liquid you’re left with is your cabbage-juice indicator. Dilute it with some water and proceed with the experiment, using it instead of bromothymol blue. You will need to experiment with the ratio of water to cabbage juice to see what dilution gives you good results. Note that unlike bromothymol blue, cabbage-juice indicator turns pink, not yellow, in the presence of an acid.

References:

• Dr. Jürgen Schieber (Indiana University, Geology 1425 course notes):  Chapter 8: The Importance of Carbon for Climate Regulation 
• Mathez, E. A. (2009). Climate Change: The Science of Global Warming and Our Energy Future . Columbia University Press, New York. 
• NOAA Ocean Acidification Program: What is Ocean Acidification (OA)?
• NOAA PMEL Carbon Program:  What is Ocean Acidification?                                            

Thanks to Chris Sabine of NOAA’s Pacific Marine Environmental Lab and t o Jim Bishop of University of California at Berkeley for sharing their expertise.

Ocean Acidification in a Cup

Exploratorium

This model of ocean-atmosphere interaction shows how carbon dioxide gas diffuses into water, causing the water to become more acidic. The video demonstration and instruction provide an explanation of the chemistry behind this change and the consequences of ocean acidification. The video also addresses a misconception about how ocean acidification affects shelled organisms.

Notes from our reviewers

The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials .

• Teaching Tips The instructions for this experiment provide alternatives for lab equipment and materials that might be unavailable, such as a substitute for the acid indicator bromothymol blue.
• About the Science This classroom experiment allows students to see the process of ocean acidification in action. It creates a carbon-dioxide rich atmosphere above a layer of water with a pH indicator in a cup. The carbon dioxide diffuses into the water and eventually raises the pH, which can be seen with the pH indicator. The website describes the processes of ocean acidification, the fast carbon cycle, and how these processes affect sea life. Comments from expert scientist: Scientific strengths: Easy to do, though the required supply of bromothymol blue might be difficult in some schools (thinking of schools without a chemistry shop). Suggestions: None.
• About the Pedagogy This is a controlled experiment that can be completed in a typical classroom laboratory setting. Students will create a model of an ocean-atmosphere interaction that shows how carbon dioxide gas diffuses into water, and compare it with a control. Before conducting the experiment, students should understand how an acid indicator works and the fact that mixing vinegar and baking soda creates CO2 gas. This classroom experiment can be done as a demonstration or a lab activity. The website provides explanations, references, and discussion questions, and teaching tips.
• Technical Details/Ease of Use Video provides an example of how to do the demonstration. Instructions are very comprehensive and easy to follow. This experiment can be carried out with typical classroom laboratory materials and provides useful tips for teachers.

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Sanctuaries resource collection: Ocean acidification

In the 200-plus years since the industrial revolution began, the concentration of carbon dioxide (CO 2 ) in the atmosphere has increased due to human actions. During this time, the pH of surface ocean waters has fallen by 0.1 pH units. This might not sound like much, but the pH scale is logarithmic, so this change represents approximately a 30 percent increase in acidity.

A pteropod shell is shown dissolving over time in seawater with a lower pH. When carbon dioxide is absorbed by the ocean from the atmosphere, the chemistry of the seawater is changed. (Image credit: NOAA)

The ocean absorbs about 30% of the carbon dioxide (CO 2 ) that is released in the atmosphere. As levels of atmospheric CO 2 increase from human activity such as burning fossil fuels (e.g., car emissions) and changing land use (e.g., deforestation), the amount of carbon dioxide absorbed by the ocean also increases.  When CO 2 is absorbed by seawater, a series of chemical reactions occur resulting in the increased concentration of hydrogen ions. This process has far reaching implications for the ocean and the creatures that live there.

The pH scale

The pH scale runs from 0 to 14, with 7 being a neutral pH. Anything higher than 7 is basic (or alkaline) and anything lower than 7 is acidic. The pH scale is an inverse of hydrogen ion concentration, so more hydrogen ions translates to higher acidity and a lower pH.

Carbon dioxide and seawater 

Carbon dioxide, which is naturally in the atmosphere, dissolves into seawater. Water and carbon dioxide combine to form carbonic acid (H 2 CO 3 ), a weak acid that breaks (or “dissociates”) into hydrogen ions (H + ) and bicarbonate ions (HCO 3 - ).

Because of human-driven increased levels of carbon dioxide in the atmosphere, there is more CO 2 dissolving into the ocean. The ocean’s average pH is now around 8.1 offsite link , which is basic (or alkaline), but as the ocean continues to absorb more CO 2 , the pH decreases and the ocean becomes more acidic.

Alison Novara, a 2022 EPP/MSI Scholar, spent her second summer internship at NOAA’s Geophysical Fluid Dynamics Laboratory studying whether ocean acidification could cause populations of these animals to collapse or change their habitat range.

Impacts of ocean acidification on shell builders

Ocean acidification is already impacting many ocean species, especially organisms like oysters and corals that make hard shells and skeletons by combining calcium and carbonate from seawater. However, as ocean acidification increases, available carbonate ions (CO32-) bond with excess hydrogen, resulting in fewer carbonate ions available for calcifying organisms to build and maintain their shells, skeletons, and other calcium carbonate structures. If the pH gets too low, shells and skeletons can even begin to dissolve.

The pteropod , or "sea butterfly," is a tiny sea snail about the size of a small pea. Pteropods are an important part of many food webs and eaten by organisms ranging in size from tiny krill to whales. When pteropod shells were placed in sea water with pH and carbonate levels projected for the year 2100, the shells slowly dissolved after 45 days. Researchers have already discovered severe levels of pteropod shell dissolution offsite link in the Southern Ocean, which encircles Antarctica.

To enable equitable and sustainable change, it is vital to connect with people through ocean acidification communication that engages and empowers people to take action, especially in the most at-risk regions.

Ocean acidification impacts on fish and seaweeds

Changes in ocean chemistry can affect the behavior of non-calcifying organisms as well. The ability of some fish, like clownfish , to detect predators is decreased in more acidic waters. Studies have shown that decreased pH levels also affect the ability of larval clownfish offsite link to locate suitable habitat. When these organisms are at risk, the entire food web may also be at risk.

While some species will be harmed by ocean acidification, algae and seagrasses may benefit from higher CO 2 conditions in the ocean, as they require CO 2 for photosynthesis just like plants on land. There are some ongoing studies examining if growing seaweed can help slow ocean acidification.

A recent report shows global carbon dioxide emissions remain at record levels and natural carbon sinks are being impacted by climate change. The report also provides a detailed accounting of carbon storage in the ocean and land.

Our changing ocean

Estimates of future carbon dioxide levels, based on business-as-usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could have a pH around 7.8 The last time the ocean pH was this low was during the middle Miocene , 14-17 million years ago. The Earth was several degrees warmer and a major extinction event was occurring.

Ocean acidification is currently affecting the entire ocean, including coastal estuaries and waterways . Billions of people worldwide rely on food from the ocean as their primary source of protein . Many jobs and economies in the U.S. and around the world depend on the fish and shellfish that live in the ocean.

Current research

Ocean acidification is one aspect of global climate change . Anything we do to mitigate climate change today will benefit the future of the ocean as well. Over the last decade, there has been much focus in the ocean science community on studying the potential impacts of ocean acidification. NOAA's Ocean Acidification Program serves to build relationships between scientists, resource managers, policy makers, and the public in order to research and monitor the effects of changing ocean chemistry on economically and ecologically important ecosystems such as fisheries and coral reefs.

Because sustained efforts to monitor ocean acidification worldwide are only beginning, it is currently impossible to predict exactly how ocean acidification impacts will cascade throughout the marine food web and affect the overall structure of marine ecosystems. With the pace of ocean acidification accelerating, scientists, resource managers, and policymakers recognize the urgent need to strengthen the science as a basis for sound decision making and action.

A NOAA-funded study has documented that ocean acidification along the U.S. Pacific Northwest coast is impacting the shells and sensory organs of some young Dungeness crab, a prized crustacean that supports the most valuable fishery on the West Coast.

EDUCATION CONNECTION

Ocean acidification is a problem that impacts the ocean ecosystem as well as commercial industries like oyster farms. This topic can be taught in conjunction with lessons about food webs and ecosystems, the environmental impacts of climate change and CO 2 emissions, and chemistry lessons concerning real-life applications. Students can explore data, including real-time information about carbon dioxide levels in seawater and in the atmosphere.

Exploratorium

This learning activity takes 30 minutes.

Middle School (see details)

Middle school, disciplinary core ideas: 3.

MS-ESS3.C1: Human activities have significantly altered the biosphere, sometimes damaging or destroying natural habitats and causing the extinction of other species. But changes to Earth’s environments can have different impacts (negative and positive) for different living things.

MS-LS2.A1: Organisms, and populations of organisms, are dependent on their environmental interactions both with other living things and with nonliving factors.

MS-PS1.B1: Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

Cross Cutting Concepts: 2

MS-C2.2: Cause and effect relationships may be used to predict phenomena in natural or designed systems.

MS-C4.2: Models can be used to represent systems and their interactions—such as inputs, processes and outputs—and energy, matter, and information flows within systems.

Science and Engineering Practices: 2

MS-P1.1: Ask questions that arise from careful observation of phenomena, models, or unexpected results, to clarify and/or seek additional information.

MS-P2.5: Develop and/or use a model to predict and/or describe phenomena.

High School (see details)

High school, disciplinary core ideas: 2.

HS-LS2.C2: Moreover, anthropogenic changes (induced by human activity) in the environment—including habitat destruction, pollution, introduction of invasive species, overexploitation, and climate change—can disrupt an ecosystem and threaten the survival of some species.

HS-PS1.B3: The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

HS-C2.2: Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system.

HS-C4.3: Models (e.g., physical, mathematical, computer models) can be used to simulate systems and interactions—including energy, matter, and information flows—within and between systems at different scales.

HS-P1.1: Ask questions that arise from careful observation of phenomena, or unexpected results, to clarify and/or seek additional information.

HS-P2.6: Develop and/or use a model (including mathematical and computational) to generate data to support explanations, predict phenomena, analyze systems, and/or solve problems.

Grade Level

Climate literacy.

This Short Demonstration/Experiment builds on the following concepts of Climate Literacy .

Click a topic below for supporting information, teaching ideas, and sample activities.

• Climate is complex
• Life affects climate; climate affects life
• Humans affect climate
• Climate change has consequences

Notes From Our Reviewers The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials Teaching Tips | Science | Pedagogy | Technical Details

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Bubblegum coral appear comfortable nearly everywhere outside of the tropics – where they can grow between 200 and 1300m of depth.

Deep-water corals are damaged beep-water corals are damaged beep-water corals are damaged beep-water corals are damaged beep-water corals are damaged beep-water corals are damaged by a number of things: deep-water trawling, long line fishing, and oil and gas exploration., like aragonitic corals, bubblegum corals are likely to be affected by changes in calcite saturation with depth..

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• Published: 23 July 2018

Current understanding and challenges for oceans in a higher-CO 2 world

• Catriona L. Hurd 1 ,
• Andrew Lenton 2 , 3 ,
• Bronte Tilbrook 2 , 3 &
• Philip W. Boyd 1 , 3  

Nature Climate Change volume  8 ,  pages 686–694 ( 2018 ) Cite this article

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• Biogeochemistry
• Climate-change ecology
• Climate-change impacts
• Ocean sciences

Ocean acidification is a global phenomenon, but it is overlaid by pronounced regional variability modulated by local physics, chemistry and biology. Recognition of its multifaceted nature and the interplay of acidification with other ocean drivers has led to international and regional initiatives to establish observation networks and develop unifying principles for biological responses. There is growing awareness of the threat presented by ocean acidification to ecosystem services and the socio-economic consequences are becoming increasingly apparent and quantifiable. In this higher-CO 2 world, future challenges involve better design and rigorous testing of adaptation, mitigation and intervention options to offset the effects of ocean acidification at scales ranging from local to regional.

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Acknowledgements

We acknowledge the sponsors and participants of the 4th International Symposium on the Ocean in a High CO 2 World and the 3rd Global Ocean Acidification Observing Network workshop that helped define the research needs and directions. This project was supported under Australian Research Council’s Special Research Initiative for Antarctic Gateway Partnership (Project ID SR140300001). P.W.B. acknowledges support from the Australian Research Council (Laureate Fellowship FL160100131). B.T. and P.W.B were supported by Antarctic Climate and Ecosystem Co-operative Research Centre.

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Hurd, C.L., Lenton, A., Tilbrook, B. et al. Current understanding and challenges for oceans in a higher-CO 2 world. Nature Clim Change 8 , 686–694 (2018). https://doi.org/10.1038/s41558-018-0211-0

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Received : 17 September 2017

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Accepted : 30 May 2018

Published : 23 July 2018

Issue Date : August 2018

DOI : https://doi.org/10.1038/s41558-018-0211-0

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Ocean Acidification

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Description

In this hands-on activity, students simulate the effects of decreasing pH caused by rising levels of atmospheric carbon dioxide.

Human activity is causing the concentration of atmospheric carbon dioxide to increase. In addition to its role as a greenhouse gas, carbon dioxide reacts with water to form a weak acid called carbonic acid, which lowers the pH of seawater. In this activity, students simulate this process by blowing through a straw into a beaker of artificial seawater and measuring the change in pH. Using the provided graph, they determine the atmospheric carbon dioxide concentration that would produce the same pH change in the oceans. Finally, students determine how many years it would take to reach this concentration at the current rate of emissions.

The “Resource Google Folder” link directs to a Google Drive folder of resource documents in the Google Docs format. Not all downloadable documents for the resource may be available in this format. The Google Drive folder is set as “View Only”; to save a copy of a document in this folder to your Google Drive, open that document, then select File → “Make a copy.” These documents can be copied, modified, and distributed online following the Terms of Use listed in the “Details” section below, including crediting BioInteractive.

Student Learning Targets

• ​​​​​​Explain the role of atmospheric CO 2 in ocean acidification.
• Collect, analyze, and interpret data to draw conclusions.
• Use models of atmospheric CO 2 concentrations to make predictions on the impact of ocean acidification on marine ecosystems.

Estimated Time

acidification, alkalinity, calcium carbonate, chemical reaction, concentration, exoskeleton, food web, marine biology, oceanography, pH, soluble

Primary Literature

Caldeira, Ken, and Michael E. Wickett. “Anthropogenic Carbon and Ocean pH.” Nature 425, 6956 (2003): 365. https://doi.org/10.1038/425365a . Fine, Maoz, and Dan Tchernov. “Scleractinian Coral Species Survive and Recover from Decalcification.” Science 315, 5820 (2007): 1811. https://doi.org/10.1126/science.1137094 . To access this article, set up a free AAAS account .

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Please see the Terms of Use for information on how this resource can be used.

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Version history, curriculum connections, ngss (2013).

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AP Biology (2019)

SYI-1.H, SYI-2.B; SP1, SP2, SP3

IB Biology (2016)

Ap environmental science (2020).

Topic(s): 1.1, 9.7 Learning Objectives & Practices: ERT-1.A, STB-4.H, SP1, SP2, SP4

IB Environmental Systems and Societies (2017)

Common core (2010).

ELA.RST.9–12.3, ELA.RST.9–12.7 Math.S-ID.3; MP1

Vision and Change (2009)

CC5; DP2, DP3

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Ocean Acidification Lesson Plans and Activities

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This collection of lesson plans and engaging activities can be utilized by teachers and educators of various grade levels, youth organizations, and others to educate students and young people about ocean acidification. Explore this issue through case studies, activity books, interactive stories, and more.

Mystery of the Disappearing Shells

Students conduct an experiment to examine the effects of acidic solutions on shells. They explore causes of ocean acidification and impacts on marine life, including the impacts of acidified seawater on bivalves, such as clams, mussels and oysters. They also discuss ways of reducing levels of carbon dioxide in the atmosphere to mitigate the problem.

Marine Osteoporosis

In this lesson students will explore the effects of acidic oceans on certain marine organisms, in the ocean food web, and to humans. Students will conduct a science experiment using the scientific method to see the effects of increased acidity on certain species. They will also investigate the causes for increased ocean acidity and discuss ways to minimize the impact as an individual and as a society.

Help Nemo Find His Home!

This lesson focuses on understanding the impacts of ocean acidification on the olfactory senses of clownfish. Students will be able to define ocean acidification and understand how specific species such as the clownfish may be affected by the increasing acidity of the ocean.

Ocean Acidification Experiment: Impacts of carbonated seawater on mussel and oyster shells

This lesson focuses on understanding the impacts of acidified seawater on mussel and oyster shells. Students will run experiments exposing shells with seawater at different levels of acidity representing current and potential future ocean conditions.

Ocean Acidification: pH and the Ocean’s Balance

About a quarter of the carbon dioxide emitted into the atmosphere from the burning of fossil fuels, ends up in our ocean. Carbon dioxide is an “acid gas” and causes the ocean to increase in acidity, which is represented by a lower pH.

Ocean Acidification: Building Blocks of the Sea

Human actions on land are connected to changes in the atmosphere, and thus, the ocean. The health and survival of ocean creatures is at risk because of the change in the ocean’s chemical composition due to additional carbon dioxide that is dissolved into sea water from the burning of fossil fuels and land use changes.

Ocean Acidification: Rugose Reef Tag

Coral reefs are extremely important ecosystems to both marine organisms and humans. The health of coral reefs and the organisms that live within them is at risk because of the change in the ocean’s composition due to additional carbon dioxide that is dissolved into sea water from the burning of fossil fuels and land use change.

Acidification: What does it mean for the oysters?

Through this activity, students will be able to understand and value the importance of how human activities influence the chemistry and thus health of the ocean ecosystem and organisms and understand and value the importance of how changes in ocean ecosystems affect marine life (specifically calcium carbonate shell and building) and human life.

Whale Jenga: A Food Web Game

Students will use the game Jenga to learn about the marine food web and how small changes in the food web can have large effects on other organisms.

Dungeness Crab Case Study

Dungeness crab is a valuable species throughout the national marine sanctuaries of the West Coast from Washington state through California. This communication toolkit is designed for educators and communicators to use to teach others about the impact of ocean acidification on Dungeness crab.

Florida Keys National Marine Sanctuaries Coral Restoration Activity

Students will research the ecology of coral reefs, natural and anthropogenic threats to corals, and the science of coral restoration. In pairs, students will design and make an argument for a proposed new coral nursery to be placed within Florida Keys National Marine Sanctuary.

Deep-Sea Coral Communities Curriculum

This curriculum takes students into the deep sea to identify the soft corals, hard corals, invertebrates and fish found in these communities and to investigate the unique biology of deep-sea corals. Learn the threats these animals face and what we can do to help protect them.

Channel Islands Middle School Ocean Acidification Curriculum

The Channel Islands National Park and Channel Islands National Marine Sanctuary Ocean Acidification Curriculum is a series of middle school lessons about ocean acidification that use the Park and Sanctuary as the backdrop for learning about ocean acidification.

Data In the Classroom: Understanding Ocean & Coastal Acidification

Carbon dioxide in the atmosphere is rising, but what does this mean for the world's ocean? Using data from NOAA, students will explore relationships between carbon dioxide, ocean pH and aragonite saturation state.

NOAA Ocean Acidification Resource Collection

OA education resources are distributed across many websites and program offices at NOAA and partner websites. This portal is designed to help you access these resources from one location. Check out NOAA’s OA Resource Collection.

Ocean Acidification's impact on oysters and other shellfish

The world's ocean is absorbing carbon dioxide at an unprecedented rate and the resulting acidification is transforming marine ecosystems.

What is Ocean Acidification?

This site has a potentially helpful background on the complex chemical interactions and impacts of carbon dioxide from the atmosphere on the marine ecosystem. Additionally, this site provides links to papers, data, and graphs, which will aid further investigation.

Data in the Classroom: Investigating Coral Bleaching Using Real Data

Coral reefs are one of the most diverse ecosystems on the planet. In this module, students will use real data to investigate the consequences of rising sea surface temperature on coral reefs. They will also consider the importance of coral reefs in their own lives.

Discover Your Changing World with NOAA Activity Book

Climate Science Literacy is an understanding of your influence on climate and climate’s influence on you and society. Utilize this resource to engage students in climate focused activities, including how carbon dioxide makes the ocean increase in acidity, the greenhouse effect, and more.

Coastal Acidification Interactive Story

Utilize this animated interactive activity to learn about the process of coastal acidification, fossil fuels, the impact of acidification on animal species, solutions to this problem, and more.

Ocean Acidification Resource Exchange

The Ocean Acidification Information Exchange is an online community for professionals involved with or interested in the topics of ocean and coastal acidification (OCA). Our mission is to respond and adapt to OCA by fostering an online environment built on trust, where our members feel empowered to ask, answer, and learn from one another.

OA Curriculum Collection

This webinar will walk you through OAcurriculumcollection.org - a new searchable database of lessons and supplemental materials on ocean acidification. Our purpose in creating this site is to make it easier for educators and communicators to find and share OA materials, and to identify gaps where materials are needed.

Ocean Acidification: Garden of the Salish Sea Curriculum

Our webinar will introduce teachers and educators to our program. We'll give you our recipe for inspiring curiosity and connecting students to intertidal ecosystems through shellfish studies. From sample lessons to our OA lab series and field inquiry we hope you'll see how students are motivated to become stewards.

Visualizing Change: New Tools for Educators

Would you like tools to help interpret complex, global-scale data and issues like ocean acidification in engaging and empowering ways? This webinar reviews such tools, developed by the Visualizing Change project.

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First controlled experiments on ocean acidification in the deep sea

After six years of design and testing, MBARI scientists have a sophisticated new tool for studying the effects of ocean acidification on deep-sea animals. This complex system, the Free-Ocean Carbon Enrichment (FOCE) experiment, is the only experiment in the world that allows researchers to study ocean-acidification impacts on deep-sea animals in their native habitat, using free-flowing seawater.

The idea behind FOCE is relatively simple—to create a semi-enclosed test area on the seafloor where the seawater’s pH (an indicator of acidity) can be precisely controlled for weeks or months at a time. Small seafloor animals are placed in the test chamber, where their behavior and physiological responses can be monitored. The idea is to observe the behavior of seafloor animals without subjecting them to the stresses of being removed from the deep sea and living in a laboratory on shore.

MBARI marine chemist  Peter Brewer  came up with the idea for FOCE in about 2003. Brewer had read about experiments on land, in which terrestrial plants were exposed to elevated levels of carbon dioxide for long periods of time. Such Free-Air Carbon dioxide Enrichment ( FACE ) experiments use a series of carbon-dioxide emitters arranged in a large ring, up to 30 meters (100 feet) across. Carbon dioxide is released from emitters from the windward side of the ring. The result is that plants within the ring are exposed to consistently elevated concentrations of carbon dioxide, regardless of the wind speed or direction.

Brewer decided to try similar experiments underwater. His initial design looked like a bird cage, with pipes emitting acidified seawater from the up-current side of the cage. However, after a few tank and ocean tests, Brewer’s team discovered that it took several minutes for the acidified seawater to come to chemical equilibrium with the surrounding seawater. By this time, the acidified seawater had been carried hundreds of meters down-current of the cage.

Faced with this challenge, the researchers went back to the drawing board and developed an entirely new system—a 10-meter-long, rectangular flume made out of clear plastic. Seawater mixed with carbon dioxide is released at one end of the flume and is pulled through the flume by small impellers. Seawater can be introduced from either end of the flume, depending on the direction of the prevailing currents. The acidified seawater flows slowly through a series of baffles, allowing it to completely mix with the surrounding seawater before it enters a central experimental chamber in the center of the flume.

Within the experimental chamber, researchers can place the seafloor animals whose response to ocean acidification is to be tested. Around the edges of the pen are sensors to measure pH, water temperature, salinity, and currents, as well as cameras to record the activity of animals within the chamber.

For the past three years, a team of engineers and scientists led by  William Kirkwood  have been testing and refining the deep-sea FOCE system. Along the way they had to solve a number of technical challenges. For example, none of the commercial pH sensors they tried would give reliable data when deployed on FOCE in the deep sea for months at a time. So the MBARI engineers had to redesign and replace the electronics within the pH sensor. They also had to develop a computer-controlled system that would mix liquid carbon dioxide with seawater and feed carefully controlled amounts into either end of the flume. By summer 2011, they had gotten the system to the point where they could keep the pH inside the chamber relatively constant (to within 0.1 pH unit).

The FOCE experiment is currently hooked up to the  MARS cabled observatory , about 25 kilometers west-northwest of Monterey and 900 meters below the ocean surface. The observatory supplies power to the experiment’s motors, lights, cameras, and sensors. The observatory’s fiber-optic data link to MBARI allows researchers to monitor the instruments and video cameras and to control the FOCE experiment in real time from their offices on shore.

In September and October 2011, MBARI marine biologist  Jim Barry  conducted the first biology experiments using the FOCE flume. To test the effects of acidification on a type of common deep-sea urchin,  Strongylocentrotus fragilis , Barry devised an ingenious system for documenting changes in the urchin’s behavior.

Barry’s team prepared for the experiment by using MBARI’s remotely operated vehicles (ROVs) to gather about 60 urchins from an area near the MARS observatory. About 30 of these urchins were placed in a mesh bag in the experimental chamber of the FOCE flume. Another 30 urchins were placed in a bag in a similar chamber nearby, which was exposed to normal seawater. Being held in mesh bags did not bother the urchins because they often gather in dense aggregations on the seafloor.

Within each experimental chamber, the ROV placed a plastic box containing five urchin “raceways” (see photo). Every week or so, Barry’s team used an ROV to remove five urchins from the bag in each chamber. They then placed one urchin at the end of each of the five raceways. At the other end of the raceways, the researchers placed the urchins’ favorite food—a mass of decomposing kelp.

After placing the urchins in the raceways, both in the FOCE experimental chamber and in the chamber containing normal seawater, the researchers used video cameras to observe how rapidly each urchin moved toward its food. After each week-long “race,” the urchins were removed from the raceways and taken to the laboratory, where the researchers looked for physiological effects on the animals. After the urchins were removed, a new group of urchins was placed in the raceways, and the experiment was repeated.

Seawater in the deep waters of Monterey Bay is often slightly basic, with a pH of about 7.6 (neutral freshwater has a pH of 7.0). Brewer and other researchers have estimated that by the year 2100, the average pH of surface waters across the world ocean could drop by as much as 0.4 pH units. Eventually, that pH reduction will work its way down into the deep sea. During the recent experiments, Barry’s team tested their urchins in seawater that had a pH as low as 7.1.

The initial results were surprising. Barry said, “Based on previous laboratory experiments, I expected the urchins to just shut down. But even after three weeks in the chamber, they were running back and forth in the raceways like little ping-pong balls.”

Over the next few months, Barry’s team will analyze videos of urchins in both acidified and normal seawater and apply statistics to look for differences in their activity levels—how fast and how far they moved. Barry suspects that this particular species of urchin is relatively tolerant to somewhat acidic conditions, but will likely show somewhat less activity in acidified seawater than in normal seawater.

Having gotten the deep-sea FOCE experiment up and running, MBARI engineers have now turned their attention to several similar projects to measure the effects of ocean acidification in shallow water. One such system is already in operation at  Heron Island  in Australia. Closer to home, the team is designing a system to be placed just outside the kelp beds at Hopkins Marine Station in Pacific Grove. They are also working with researchers planning similar experiments on the east coast of the United States, in France, England, and China, and even under the Antarctic ice.

With the completion of initial deep-water experiments in Monterey Bay, and the development of several shallow-water systems, FOCE has become yet another example of a long-term MBARI engineering effort that is benefiting ocean researchers around the world.

For additional information or images relating to this article, please contact [email protected].

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Researchers

Peter G. Brewer

Senior Fellow/Ocean Chemist

James Barry

Senior Scientist & Benthic Ecologist

MBARI mourns the passing of visionary marine biologist William Hamner

MBARI and the David and Lucile Packard Foundation celebrate a lasting legacy for ocean exploration

New research reveals the importance of storms in air-sea carbon exchange in the Southern Ocean

• Vinegar is to an Eggshell What Ocean Acidification is to Marine Ecosystems?
• Phenomenon-based Learning

Leave an egg in a cup of vinegar overnight, and the shell will start to dissolve off the egg.

This is because the acetic acid in the vinegar neutralizes the calcium carbonate in the eggshell, releasing carbon dioxide and weakening the shell. Now imagine this same science experiment but with an ocean full shellfish in a sea of acidifying water (less basic, to be accurate). With current carbon dioxide (CO 2 ) emissions levels, we are running this experiment in real-time. The ocean acts as a carbon sink, dissolving about 30 percent of CO 2 released into the atmosphere. The CO 2 in the ocean decreases the pH of the seawater, which can have a similar “dissolving” effect on calcifying organisms—animals that have hard structures such as corals, oysters, and sea urchins. Ocean acidification also affects the ecosystem as a whole by disrupting food webs.

Guiding Questions

• What chemical processes are involved in ocean acidification?
• How might ocean acidification affect calcifying organisms?
• What other parts of the ecosystem are impacted by an acidifying ocean?
• What steps can humans take to limit CO2 emissions?

Download an SOS playlist for this module .

Acidifying Oceans: Oceans and Climate Change

This short video draws together ocean acidification and its anthropogenic causes.

Changing Climate, Changing Ocean

A short film that explores the impacts of climate change on our oceans, including its impacts on ecosystems.

Ocean Acidification: Saturation State

These two datasets model the past and project the future aragonite saturation and surface pH from 1861 to 2100. The factors measured are both indicators of ocean acidification.

Ocean-Atmosphere CO2 Exchange

The ocean serves as a carbon sink, however as it absorbs more and more CO2 (as seen in this model), it becomes less basic than before.

For SOSx use Carbon Dioxide Concentration: GEOS-5 Model .

Smithsonian Ocean

Studying acidification in the lab.

Researchers can study ocean acidification in the lab by rearing organisms in seawater with variable pH and measuring if they grow, eat, breathe, reproduce, or develop differently. It's common, for example, to have one tank of seawater with pH that is common in the ocean today, one that is a little bit higher, and one that is a lot higher. While this doesn't usually tell scientists how whole ecosystems will respond to acidification, it can help figure out the general impacts to a single organism or predator-prey pairs. Here, researchers with BIOACID rear Lophelia deep-sea corals in seawater with variable pH.

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Shop Chemistry An Experiment to Help Students Understand Ocean Acidification through pH Sharing ideas and inspiration for engagement, inclusion, and excellence in STEM Home  >  Blog  >  An Experiment to Help Students Understand Ocean Acidification through pH An Experiment to Help Students Understand Ocean Acidification through pH

By Vernier Science Education

Today’s environmental challenges call for ongoing discussions and hands-on learning opportunities to deepen student understanding and engagement in environmental stewardship. One such activity is to investigate how the burning of fossil fuels not only contributes to climate change, but also leads to changes in environmental chemistry, such as the increase in ocean acidification and subsequent increase in acid rain .

The Connection Between Fossil Fuels and Ocean Chemistry

The combustion of fossil fuels releases a cocktail of gases into the atmosphere, including carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), and nitrogen oxide (NO 2 ). While the link between these emissions and climate change is well documented, their impact on the world’s oceans is equally concerning but less visible. Oceans act as a carbon sink, absorbing CO 2 from the atmosphere. However, the excessive amounts of CO 2 resulting from human activities leads to a notable decrease in water pH, making the oceans more acidic. This acidification can have detrimental effects on marine life and ecosystems, disrupting the delicate balance that sustains the ocean’s biodiversity.

Help your students contextualize the impact of ocean acidification with this video exploring how students, scientists, and fishermen from Washington’s Olympic Peninsula coast are responding to changing marine ecosystems.

A Hands-On Experiment to Illustrate Real-Time pH Change

In this experiment, students explore the science behind ocean acidification by using a Go Direct ® pH Sensor and Vernier Graphical Analysis ® to measure changes in pH and study the effect of dissolved CO 2 on the pH of water.  There are a few variations on this experiment, including qualitative demonstrations like having students blow bubbles through a straw in a water sample or quantitative experiments that use Alka Seltzer ® or dry ice to introduce excess CO 2 . One of the benefits of this particular variation is that using a paraffin candle more accurately models the reality of how power plants, exhaust from combustion engines, and other human activities produce a mix of gases in the atmosphere.

Essentials for this Experiment

• Chromebook™, computer, or mobile device
• Vernier Graphical Analysis app
• Go Direct pH Sensor or Go Direct Tris-Compatible Flat pH Sensor
• Faucet vacuum aspirator
• Vacuum flask and tubing
• Stopper modified to fit flask and hold pH probe and plastic tubing
• Glass funnel
• Matches or lighter
• Ring stand and clamp (2)
• Distilled water
• Acid/base indicator (optional)

Prepare your lab setup near a sink. Start by soaking your pH sensor in a pH 7 solution while you prep the lab so that the sensor has a quicker response time. Connect the vacuum aspirator to the faucet along with the tubing for the vacuum flask.

Fill the vacuum flask with distilled water and add a universal indicator if desired. We recommend including the indicator to help students visualize the qualitative change in acidity alongside the quantitative data being collected by the sensor. Secure the flask to the ring stand. Carefully fit the tubing to the flask.

On a second ring stand, set up the glass funnel over the candle. Thread the plastic tubing from the funnel as well as the pH sensor through the modified stopper. Insert both the tubing and tip of the probe into the vacuum flask, ensuring that the tip of the probe is fully submerged in the water sample and that the stopper creates an airtight seal.

Connect the pH probe via Bluetooth ® wireless technology or USB to your device and launch Vernier Graphical Analysis.

Conducting the Experiment

Encourage students to make predictions about what they think will happen when air is introduced through the tubing and when the candle’s combustion gases mix with the water. Will the pH change? In which direction? What will that mean about the acidity of the water?

Turn on the faucet and start data collection in Graphical Analysis. Allow 10–20 seconds for the pH sensor to reach equilibrium, and then light the candle under the glass funnel. As the candle burns, it mimics the pollutants from fossil fuel combustion entering the ocean. These gases dissolve in the water, forming acids and lowering the pH. This real-time data visualization allows students to witness the impact of pollution on ocean chemistry firsthand.

Experiment Tips

• To make the experiment even more illustrative of the impact on the natural environment, try using different water samples, including ocean water and locally sourced fresh water.
• This experiment can also be conducted using a LabQuest ® interface in lieu of Graphical Analysis and a laptop or mobile device.
• If your data is inconsistent, use this as an opportunity to interrogate why that might be!

Discussion Questions

Following the experiment, discuss student observations and their broader environmental implications.

• How does this experiment reflect the natural process of ocean acidification?
• How might the increased acidity in the ocean correlate to an increase in acid rain?
• What might be the impact of increased ocean acidity on marine ecosystems?
• How can we, as individuals and communities, reduce our carbon footprint?

Looking for more ways to engage students in environmental science explorations? Explore our resources . Questions? We’re always here to help! Reach out to [email protected] or call 888‑837‑6437.

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Related articles.

Four Laws, One Sensor: Introducing Students to Gas Laws Using the Go Direct Gas Pressure Sensor

Why Isn’t There Dead Stuff Everywhere?! Exploring the Nature of Decomposition with a CO 2 Gas Investigation

Where Math Meets Science: Connecting Vernier Go Direct Sensors and TI-Nspire Technology

How to Introduce Your Students to Data-⁠Collection Basics

Three Ready-to-Use 3D Physics Investigations to Maximize Impact with Vernier Sensors

Choosing the Right pH Sensor for Your Classroom or Lab

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Changes in seawater chemistry

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ocean acidification

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• National Geographic - Environment - Ocean Acidification
• National Oceanic and Atmospheric Administration - PMEL Carbon Program - What is Ocean Acidification?
• Table Of Contents

ocean acidification , the worldwide reduction in the pH of seawater as a consequence of the absorption of large amounts of carbon dioxide (CO 2 ) by the oceans . Ocean acidification is largely the result of loading Earth’s atmosphere with large quantities of CO 2 , produced by vehicles and industrial and agricultural processes. Since the beginning of the Industrial Revolution about 1750, roughly one-third to one-half of the CO 2 released into Earth’s atmosphere by human activities has been absorbed by the oceans. During that time period, scientists have estimated, the average pH of seawater declined from 8.19 to 8.05, which corresponds to a 30 percent increase in acidity.

Some scientists estimate that the pace of ocean acidification since the beginning of the Industrial Revolution has been approximately 100 times more rapid than at any other time during the most recent 650,000 years. They note that concentrations of atmospheric CO 2 between 1000 and 1900 ce ranged between 275 and 290 parts per million by volume (ppmv). In 2010 the average concentration was 390 ppmv, and climatologists expect the concentration to rise to between 413 and 750 ppmv by 2100, depending on the level of greenhouse gas emissions. With additional CO 2 transferred to the oceans, pH would decline further; under worst-case scenarios, seawater pH would drop to between 7.8 and 7.9 by 2100.

Marine scientists are concerned that the process of ocean acidification constitutes a threat to sea life and to the cultures that depend on the ocean for their food and livelihood. Increases in ocean acidity reduce the concentration of carbonate ions and the availability of aragonite (a significant source of calcium carbonate) in seawater. Marine scientists expect that coral , shellfish , and other marine calcifiers (that is, organisms that use carbonates) will be less able to obtain the raw materials that they use to build and maintain their skeletons and shells. These scientists also note that rising ocean acidity presents a number of other physiological problems to different groups of marine organisms and that such problems could threaten the stability of marine food chains .

The acidity of any solution is determined by the relative concentration of hydrogen ions (H + ). A larger concentration of H + ions in a solution corresponds to higher acidity, which is measured as a lower pH. When CO 2 dissolves in seawater, it creates carbonic acid (H 2 CO 3 ) and liberates H + , which subsequently reacts with carbonate ions (CO 3 2− ) and aragonite (the stable form of calcium carbonate) to form bicarbonate (HCO 3 − ). At present seawater is extremely rich in dissolved carbonate minerals. However, as ocean acidity increases, carbonate ion concentrations fall.

The absorption of CO 2 largely results from the dissolution of the gas into the upper layers of the ocean, but CO 2 is also brought into the oceans through photosynthesis and respiration . Algae and other marine photosynthesizers take in CO 2 and store it in their tissues as carbon. Carbon is then passed to zooplankton and other organisms through the food chain, and these organisms can release CO 2 to the oceans through respiration. In addition, when marine organisms die and fall to the ocean floor, CO 2 is released through the process of decomposition.

Under the worst-case scenarios outlined above, with seawater pH dropping to between 7.8 and 7.9, carbonate ion concentrations would decrease by at least 50 percent as acids in the seawater reacted with them. Under such conditions, marine calcifiers would have substantially less material to maintain their shells and skeletons. Laboratory experiments in which the pH of seawater has been lowered to approximately 7.8 (to simulate one projected oceanic pH for the year 2100) have shown that such organisms placed in these environments do not grow as well as those placed in environments characterized by early 21st-century levels of seawater acidity (pH = 8.05). As a result, their small size places them at higher risk of being eaten by predators. Furthermore, the shells of some organisms—for instance, pteropods , which serve as food for krill and whales —dissolve substantially after only six weeks in such high-acid environments.

Larger animals such as squid and fishes may also feel the effects of increasing acidity as carbonic acid concentrations rise in their body fluids. This condition, called acidosis , may cause problems with the animal’s respiration as well as with growth and reproduction .

In addition, many marine scientists suspect the substantial decline in oyster beds along the West Coast of the United States since 2005 to be caused by the increased stress ocean acidification places on oyster larvae. (It may make them more vulnerable to disease .)

Physiological changes brought on by increasing acidity have the potential to alter predator-prey relationships. Some experiments have shown that the carbonate skeletons of sea urchin larvae are smaller under conditions of increased acidity; such a decline in overall size could make them more palatable to predators who would avoid them under normal conditions. In turn, decreases in the abundance of pteropods, foraminiferans , and coccoliths would force those animals that consume them to switch to other prey. The process of switching to new food sources would cause several predator populations to decline while also placing predation pressure on organisms unaccustomed to such attention.

Many scientists worry that many marine species, some critical to the proper functioning of marine food chains, will become extinct if the pace of ocean acidification continues, because they will not have sufficient time to adapt to the changes in seawater chemistry. The world’s coral reefs , which provide habitat to many species and are often regarded by ecologists as centres of biodiversity in the oceans, could decline and even disappear if ocean acidification intensifies and carbonate ion concentrations continue to fall.

The deeper waters of the ocean are naturally more acidic than the upper layers, since CO 2 that dissolves at the surface descends with dense, cold water as part of the thermohaline circulation . The acidic lower layers of the ocean are separated from the upper layers by a boundary called the “ saturation horizon.” Above this boundary there are enough carbonates present in the water to support coral communities . In midlatitude waters and in waters closer to the poles, many so-called cold-water coral communities are found at depths that range from 40 to 1,000 metres (about 130 to 3,300 feet)—as opposed to their warm-water counterparts, the tropical coral reefs, which are rarely found below 100 metres (330 feet). Since about the year 1800, studies have shown, increased acidity has raised the saturation horizon about 50 to 200 metres (about 160 to 660 feet) in midlatitude and polar waters. This change is enough to threaten cold-water coral communities, and some scientists fear that additional communities will be placed at risk if the boundary approaches the surface of the ocean. A decline in cold-water marine calcifiers would result in a decline in reef building, and other marine organisms that depend on corals for their habitat and food would decline as well. Scientists also predict that, if ocean acidification were to increase worldwide, warm-water coral communities, which often supply food and tourism revenue to people who live near them, would suffer similar fates.

In addition, scientists predict that the reduction of marine phytoplankton populations due to rising pH levels in the oceans will produce a positive feedback that intensifies global warming . Marine phytoplankton produce dimethyl sulfide (DMS), a gas that serves as the most significant source of sulfur in Earth’s atmosphere. Sulfur in Earth’s upper atmosphere reflects some of the incoming solar radiation back into space and thus keeps it from warming Earth’s surface. Models predict that DMS production will decrease by about 18 percent by 2100 from preindustrial levels, which will result in additional radiative forcing corresponding to an atmospheric temperature increase of 0.25 °C (0.45 °F).

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Ocean acidification.

Students use a pH sensor to explore the effect of excess atmospheric carbon dioxide on water pH.

Supports NGSS Performance Expectation HS-ESS2-6: Develop a quantitative model to describe the cycling of carbon among the hydrosphere, atmosphere, geosphere, and biosphere.

Grade Level: High School

Subject: Chemistry • Earth Science • Environmental Science

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Featured Equipment

pH Storage Solution

A 500 mL bottle of storage solution for PASCO pH Electrodes.

pH Buffer Capsule Kit

Use this kit to create fresh solutions of known pH values (4, 7 & 10) for calibrating pH meters or other purposes.

Wireless pH Sensor with Display

Our best tool for measuring pH since litmus paper, now with a digital display for instant readings! Manually record data using the display, or wirelessly transmit pH values to a device to graph and analyze using software.

Wireless pH Sensor

Here’s the best tool for measuring pH since litmus paper. The Wireless pH Sensor connects via Bluetooth® to monitor the pH of solutions.

Many lab activities can be conducted with our Wireless , PASPORT , or even ScienceWorkshop sensors and equipment. For assistance with substituting compatible instruments, contact PASCO Technical Support . We're here to help. Copyright © 2018 PASCO

Source Collection: Lab #72

Essential Chemistry Teacher Lab Manual

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Ocean acidification

The oceans have absorbed between 24% and 33% of anthropogenic carbon dioxide (CO2) emissions during the past five decades. While this uptake provides a valuable service to human societies by moderating the rate and severity of climate change, it comes at a cost for the oceans. The massive input of CO2 generates sweeping changes in the chemistry of seawater, especially on the carbonate system. These changes are collectively referred to as “ocean acidification” because increased CO2 lowers seawater pH (i.e. increases its acidity).

More information

IUCN has been working on the issue of Ocean Acidification (OA) for nearly two decades, notably as the host for the OAiRUG, the international reference user group for OA.  This working group of scientific experts convened to distill the latest science on OA and to translate its findings into policy advice for governments, policy makers and other practitioners. A selection of outputs from this working group are listed below.  

Coral reefs are among the ecosystems most vulnerable to ocean acidification

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Evaluating the Evolving Ocean Acidification Risk to Dungeness Crab: Time-Series Observations and Modeling on the Olympic Coast, Washington, USA

• Author(s): Simone R. Alin , Samantha A. Siedlecki, Halle Berger, Richard A. Feely, Jeannette E. Waddell, Brendan R. Carter, Jan A. Newton, Ervin Joe Schumacker, Daniel Ayres
• Oceanography
• October 30, 2023
• Dungeness crab
• The Olympic Coast as a Sentinel: An Integrated Social-Ecological Regional Vulnerability Assessment to Ocean Acidification

The Olympic Coast of Washington is home to four Coastal Treaty Tribes who have relied on the region’s rich marine resources since time immemorial. The region is characterized by large dynamic ranges of physical and biogeochemical oceanographic parameters, particularly during the upwelling season (April–September). Here, we present novel estimates of ocean acidification metrics—pH and calcium carbonate saturation states (Ω)—representing pre-industrial, present-day (using 2010 as the index year), and near-future (2030) conditions. We compare these new estimates of past, present, and near-future ocean acidification status and seasonality to published end-of-century (2100) ocean acidification projections under a high CO 2  emissions scenario, and also to sensitivity information for Dungeness crab, a regionally important subsistence and commercial fishery species projected to show strong declines in fisheries yields and revenues later this century.

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

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

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50 more ways to reduce your carbon footprint >

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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

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:

• 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!
• Participate in habitat restoration efforts to restore habitats that help mitigate the effects of coastal acidification
• Facilitate conversations with local businesses that might be affected by ocean acidification, building a plan for the future.
• 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.
• 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