Ocean Acidification

What is Ocean Acidification?

Ocean acidification is the process of carbon dioxide (CO2) in the air being absorbed by the oceans and causing significant changes in seawater chemistry. Anthropogenic ocean acidification describes the uptake of excess human-produced CO2 by the oceans, a process that causes arise in seawater acidity.

Here are the basic facts about ocean acidification:

  • Since the beginning of the Industrial Revolution, the oceans have absorbed approximately a third of the carbon dioxide we have produced
  • This has caused an increase of 30% in surface ocean acidity.
  • If current carbon dioxide emissions continue at this rate, ocean acidity is expected to increase 100-150% percent more, relative to the beginning of the Industrial Revolution.
  • Anthropogenic ocean acidification is of great concern because, to our knowledge, it is at least 10 times faster than any natural acidification event in the past.

How are marine organisms affected?

Overall, ocean acidification has been shown to negatively impact more marine organisms than it helps. In particular, marine species that need a compound called carbonate to build skeletons or shells are negatively impacted because as seawater acidity increases, the concentration of carbonate ions in the water decreases. As this happens, it becomes more difficult for corals, shellfish, and other calcifying (carbonate-requiring) organisms to make their hard parts. Ocean acidification also hurts some fish by impairing their normal senses, causing them to misinterpret predator cues and swim toward instead of away from danger. Additionally, marine food webs may experience devastation as small organisms at their base, such as calcifying pteropods (the “sea butterfly”), experience detrimental effects of increasing acidity.

Does ocean acidification affect humans?

While the broad socioeconomic impacts of ocean acidification are poorly described, there are already affects on some local industries. In the American Pacific Northwest, the US $270 M per year shellfish industry has experienced major losses of larval shellfish, which are susceptible to die because they cannot form shells under high acidity. Some shellfish farmers have even packed up and left for more favorable conditions elsewhere. They are being called the first refugees of ocean acidification.

What can be done about ocean acidification?

While early research has shown many negative impacts of ocean acidification on marine species, there remains much to be known. More research is needed before we can accurately predict what the future oceans will look like. In the meantime, we can each play our part in slowing the rapid rate of acidification by reducing our carbon dioxide emissions and voting for political leaders who support carbon reductions.

Some shocking OA facts:

  • The oceans absorb ¼ of global anthropogenic carbon dioxide each year.
  • We're dumping the equivalent of a train car of coal — about 100 U.S. tons — into the ocean every second
  • This current rate of CO2 release is the fastest in at least the past 55 million years.
  • Less than 10% of the US public is aware of OA, according to a report on OA by the National Research Council.
  • Rising temperatures and decreasing oxygen levels in the oceans may exacerbate ocean acidification’s effects.

More OA Resources:

For basic information:
NOAA’s Ocean Acidification website
National Geographic’s Ocean Acidification website
Natural Resources Defense Council’s Ocean Acidification website
TED Talk

For information on species/ecosystems: Corals: paper
Pteropods: video
Marine ecosystems: paper

For kids: Claymation video

Contact Information

Ocean Scientists for Informed Policy
Scripps Institution of Oceanography
University of California, San Diego
9500 Gilman Drive
La Jolla, CA 92083-0202