---
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caption: 'The 36-day-old clams in the photos are a single species, Mercenaria mercenaria, grown in the laboratory under varying levels of carbon dioxide (CO<sub>2</sub>) in the air. CO<sub>2</sub> is absorbed from the air by ocean water, acidifying the water and thus reducing the ability of juvenile clams to grow their shells. As seen in the photos, where CO<sub>2</sub> levels rise progressively from left to right, 36-day-old clams (measured in microns) grown under elevated CO<sub>2</sub> levels are smaller than those grown under lower CO<sub>2</sub> levels. The highest CO<sub>2</sub> level, about 1500 parts per million (ppm; far right), is higher than most projections for the end of this century but could occur locally in some estuaries. (Figure source: Talmage and Gobler 2010<tbib>93174a81-1212-49a4-a2f8-ed8286e05bda</tbib>).'
chapter:
  description: ~
  display_name: 'Chapter 24: Oceans and Marine Resources'
  doi: 10.7930/J0RF5RZW
  identifier: oceans-marine-resources
  number: 24
  report_identifier: nca3
  sort_key: 240
  title: Oceans and Marine Resources
  url: http://nca2014.globalchange.gov/report/regions/oceans
chapter_identifier: oceans-marine-resources
cited_by: []
contributors: []
create_dt: 2013-07-09T16:19:00
description: 'The 36-day-old clams in the photos are a single species, Mercenaria mercenaria, grown in the laboratory under varying levels of carbon dioxide (CO<sub>2</sub>) in the air. CO<sub>2</sub> is absorbed from the air by ocean water, acidifying the water and thus reducing the ability of juvenile clams to grow their shells. As seen in the photos, where CO<sub>2</sub> levels rise progressively from left to right, 36-day-old clams (measured in microns) grown under elevated CO<sub>2</sub> levels are smaller than those grown under lower CO<sub>2</sub> levels. The highest CO<sub>2</sub> level, about 1500 parts per million (ppm; far right), is higher than most projections for the end of this century but could occur locally in some estuaries. (Figure source: Talmage and Gobler 2010<tbib>93174a81-1212-49a4-a2f8-ed8286e05bda</tbib>).'
display_name: '24.3: Ocean Acidification Reduces Size of Clams'
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href: http://52.38.26.42:8080/report/nca3/chapter/oceans-marine-resources/figure/ocean-acidification-reduces-size-of-clams.yaml
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    title: 'Ocean Acidification Causes Clams to Shrink - 750 ppm'
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    title: 'Ocean Acidification Causes Clams to Shrink - 1500 ppm'
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    title: 'Ocean Acidification Causes Clams to Shrink - 250 ppm'
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    title: 'Ocean Acidification Causes Clams to Shrink - 390 ppm'
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    uri: /reference/93174a81-1212-49a4-a2f8-ed8286e05bda
report:
  display_name: 'Climate Change Impacts in the United States: The Third National Climate Assessment'
report_identifier: nca3
source_citation: 'Talmage and Gobler 2010<tbib>93174a81-1212-49a4-a2f8-ed8286e05bda</tbib>'
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title: Ocean Acidification Reduces Size of Clams
type: figure
uri: /report/nca3/chapter/oceans-marine-resources/figure/ocean-acidification-reduces-size-of-clams
url: http://nca2014.globalchange.gov/highlights/report-findings/oceans/graphics/ocean-acidification-reduces-size-clams
usage_limits: Copyright protected. Obtain permission from the original figure source.