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Ocean Acidification

Grades 11-12 | Informative | Source-Based

Source Lexile®: 1120L-1380L

Learning Standards




Prompt: "Sea Change: Ocean acidification drives oyster farmers to Hawaii" explains the developing problem of ocean acidification and its impact on oysters, and "Overview of Greenhouse Gases" provides information about carbon dioxide emissions. Explain the relationship between human activities, ocean acidification and its impact on oysters and oyster farmers. Address how changing human behavior could affect the oysters. Be sure to use support from both texts and the supplementary visual "How Ocean Acidification Affects the West Coast."


Source 1

Sea Change: Ocean acidification drives oyster farmers to Hawaii (excerpt)

By Craig Welch, Seattle Times



  1. HILO, Hawaii — It appears at the end of a palm tree-lined drive, not far from piles of hardened black lava: the newest addition to the Northwest's famed oyster industry. Half an ocean from Seattle, on a green patch of island below a tropical volcano, a Washington state oyster family built a 20,000-square- foot shellfish hatchery. Ocean acidification left the Nisbet family no choice.
  2. Carbon dioxide from fossil fuel emissions had turned seawater in Willapa Bay along Washington's coast so lethal that slippery young Pacific oysters stopped growing. The same corrosive ocean water got sucked into an Oregon hatchery and routinely killed larvae the family bought as oyster seed.
  3. So the Nisbets became the closest thing the world has seen to ocean acidification refugees. They took out loans and spent $1 million and moved half their production 3,000 miles away.
  4. "I was afraid for everything we'd built," Goose Point Oyster Co. founder Dave Nisbet said of the hatchery, which opened last year. "We had to do something."
  5. Oysters started dying by the billions along the Northwest coast in 2005, and have been struggling ever since. When scientists cautiously linked the deaths to plummeting ocean pH in 2008 and 2009, few outside the West Coast's $110 million industry believed it.
  6. By the time scientists confirmed it early last year, the region's several hundred oyster growers had become a global harbinger — the first tangible sign anywhere in the world that ocean acidification already was walloping marine life and hurting people.
  7. Worried oystermen testified before Congress. A few hit the road to speak at science conferences. Washington's governor at the time, Chris Gregoire, established a task force of ocean acidification experts, who sought ways to fight this global problem locally…
  8. …And no one, anywhere, could tell them [the Nisbets] what was wrong.
  9. Then the oyster growers met the oceanographers.
  10. Dick Feely, with the National Oceanic and Atmospheric Administration, by the early 2000s was noting a dramatic change off the West Coast.
  11. Low pH water naturally occurred hundreds of feet down, where the colder water held more CO 2 . But that corrosive water was rising swiftly, getting ever closer to the surface where most of the marine life humans care about lived.
  12. In 2007, Feely organized a crew of scientists to measure and track that water from Canada to Mexico.
  13. "What surprised us was we actually saw these very corrosive waters for the very first time get to the surface in Northern California," he said.
  14. That hadn't been expected for 50 to 100 years. And that wasn't the worst of it.
  15. Because of the way the ocean circulates, the corrosive water that surfaces off Washington, California and Oregon is the result of CO2 that entered the sea decades earlier. Even if emissions get halted immediately, West Coast sea chemistry — unlike the oceans at large — would worsen for several decades before plateauing.
  16. It would take 30 to 50 years before the worst of it reached the surface.
  17. Feely published his findings in 2008.
  18. He explained to the oyster farmers that when north winds blew, deep ocean water was drawn right to the beach, which meant this newly corrosive water probably got sucked into the hatchery. That same water also flowed into the Strait of Juan de Fuca and made its way to Hood Canal.
  19. The oyster industry pleaded with Congress, which supplied money for new equipment. Over several years, the hatcheries tested their water using high-tech pH sensors. When the pH was low, baby oysters died within two days. By drawing water only when the pH was normal, shellfish production got back on track.
  20. "They told us it was like turning on headlights on a car — it was so clear what was going on," Feely said.
  21. It wasn't until 2012 that Feely and a team from Oregon State University finally showed with certainty that acidification had caused the problem. Early this summer OSU professor George Waldbusser demonstrated precisely how.
  22. The oysters were not dissolving. They were dying because the corrosive water forced the young animals to use too much energy. Acidification had robbed the water of important minerals, so the oysters worked far harder to extract what they needed to build their shells.
  23. Waldbusser still is not entirely sure why acidification has not yet hit other oyster species. It could be because other species, such as the native Olympic, have evolved to be more adaptable to high CO2, or because they rear larvae differently, or because they spawn at a time of year when corrosive water is less common. It could also be that acidification is just not quite bad enough yet to do them harm…
  24. …Growers are crushing up shells and adding chemicals to the water to make it less corrosive. Shellfish geneticists are working to breed new strains of oysters that are more resistant to low pH water.
  25. But no one thinks any of that will work forever.
  26. "I do not think people understand the seriousness of the problem," David Stick, manager of the hatchery in Hilo, said. "Ocean acidification is going to be a game-changer. It has the potential to be a real catastrophe."
  27. At the moment, the problem only strikes oysters at the very early stages of their development, within the first week or so of life.
  28. But how long will that be the case? How would they respond to changes in the food web?
  29. "The algae is changing," Stick said. "The food source that everything depends on is changing. Will things adapt? We don't know. We've never had to face anything like this before."
  30. With one young son, and a baby on the way, it's been impossible for Kathleen Nisbet not to think about her own next generation.
  31. "I don't think that our government is recognizing that ocean acidification exists," she said. "I don't think society understands the impacts it has. They think ocean acidification ... no big deal, it's a huge ocean."
  32. But the reality is, over the next decade, the world will have to make progress tackling this issue.
  33. "We're living proof," Nisbet said. "If you ignore it, it's only going to get worse. Plain and simple: It will get worse."



Source 2





Source 3

Overview of Greenhouse Gases

By Environmental Protection Agency


  1. Carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities. In 2013, CO2 accounted for about 82% of all U.S. greenhouse gas emissions from human activities. Carbon dioxide is naturally present in the atmosphere as part of the Earth's carbon cycle (the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals). Human activities are altering the carbon cycle—both by adding more CO2 to the atmosphere and by influencing the ability of natural sinks, like forests, to remove CO2 from the atmosphere. While CO2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution. [1]


U.S. Carbon Dioxide Emissions, By Source




Note: All emission estimates from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2013.

  1. The main human activity that emits CO2 is the combustion of fossil fuels (coal, natural gas, and oil) for energy and transportation, although certain industrial processes and land-use changes also emit CO2. The main sources of CO2 emissions in the United States are described below.
  • Electricity. Electricity is a significant source of energy in the United States and is used to power homes, business, and industry. The combustion of fossil fuels to generate electricity is the largest single source of CO2 emissions in the nation, accounting for about 37% of total U.S. CO2 emissions and 31% of total U.S. greenhouse gas emissions in 2013. The type of fossil fuel used to generate electricity will emit different amounts of CO2. To produce a given amount of electricity, burning coal will produce more CO2 than oil or natural gas.
  • Transportation. The combustion of fossil fuels such as gasoline and diesel to transport people and goods is the second largest source of CO2 emissions, accounting for about 31% of total U.S. CO2 emissions and 26% of total U.S. greenhouse gas emissions in 2013. This category includes transportation sources such as highway vehicles, air travel, marine transportation, and rail.
  • Industry. Many industrial processes emit CO2 through fossil fuel combustion. Several processes also produce CO2 emissions through chemical reactions that do not involve combustion, for example, the production and consumption of mineral products such as cement, the production of metals such as iron and steel, and the production of chemicals. Fossil fuel combustion from various industrial processes accounted for about 15% of total U.S. CO2 emissions and 12% of total U.S. greenhouse gas emissions in 2013. Note that many industrial processes also use electricity and therefore indirectly cause the emissions from the electricity production.
  1. Carbon dioxide is constantly being exchanged among the atmosphere, ocean, and land surface as it is both produced and absorbed by many microorganisms, plants, and animals. However, emissions and removal of CO2 by these natural processes tend to balance. Since the Industrial Revolution began around 1750, human activities have contributed substantially to climate change by adding CO2 and other heat-trapping gases to the atmosphere.
  1. In the United States, since 1990, the management of forests and non-agricultural land has acted as a net sink of CO2, which means that more CO2 is removed from the atmosphere, and stored in plants and trees, than is emitted. This sink offset about 13% of total emissions in 2013.


Emissions and Trends

  1. Carbon dioxide (CO2) emissions in the United States increased by about 7% between 1990 and 2013. Since the combustion of fossil fuel is the largest source of greenhouse gas emissions in the United States, changes in emissions from fossil fuel combustion have historically been the dominant factor affecting total U.S. emission trends. Changes in CO 2 emissions from fossil fuel combustion are influenced by many long-term and short-term factors, including population growth, economic growth, changing energy prices, new technologies, changing behavior, and seasonal temperatures. Between 1990 and 2013, the increase in CO2 emissions corresponded with increased energy use by an expanding economy and population, and an overall growth in emissions from electricity generation. Transportation emissions also contributed to the 7% increase, largely due to an increase in miles traveled by motor vehicles.


U.S. Carbon Dioxide Gas Emissions, 1990-2013



Note: All emission estimates from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2013.

  1. Going forward, CO2 emissions in the United States are projected to grow by about 1.5% between 2005 and 2020. [2]










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