Ocean acidification is a term used to describe a major shift in the chemistry of the ocean
caused by sharp increases in carbon dioxide in the global atmosphere. A portion of this
carbon dioxide is absorbed by ocean waters. This does not mean that the ocean is
turning into an "acid." It does however mean that the ocean is becoming more acidicin other words
the pH level of seawater is becoming lower and moving closer to the acid end of the scale.
Ocean acidification happens when carbon dioxide reacts with water to form carbonic acid. The rate
of ocean acidification has increased as humans continue to release rampant levels of carbon dioxide
through the burning of fossil fuels like oil, coal, and natural gas. In spring of 2013, the atmospheric concentration
of carbon dioxide reached 400 parts per million,
higher than the earth had seen in more than 800,000 years. In 2021 we passed 420 parts per million. Since
people started burning fossil fuels during
the Industrial Revolution, the global average pH of the surface ocean has decreased by 0.11 pH units, which
is a 30% increase in acidity. If carbon emissions are not reduced, by the end of the century ocean
predicted to be lower than the earth has seen in 20 million years.
What does this mean? The ocean acts as a carbon "sink," buffering our atmosphere from what would otherwise be
much higher concentrations of carbon dioxide. While this phenomenon means we're experiencing lower
atmospheric CO2 than we would without the ocean, the consequence is the increase in ocean acidity. The rate of
change in ocean pH is so much greater
than what the earth has historically seen, some marine organisms will not adapt to their new environment.
Calcifying organisms, such as shellfish and corals, are particularly vulnerable to ocean acidification, which
impedes the ability of these organisms to produce and maintain their shells. Some negative impacts have already
been documented, such as farmed
oyster larva in the Pacific Northwest unable to form shells during low pH events. Laboratory experiments
show that elevated
carbon dioxide alters clownfish behavior, making them potentially more vulnerable to predators. Coral reefs,
already impacted by rising ocean temperatures, are greatly threatened by ocean acidification. This infographic summarizes what is known about the impact of ocean acidification on
specific California marine species.
How do we address this problem? The ultimate answer is to stop burning fossil fuels. Get involved
in your community to support decisions that help fight ocean acidification. Talk to your family, neighbors, and
elected officials about ways we can reduce fossil fuel use on a community or government level and how we can
make it easier for individuals to consume less. (In 2018, the State of California passed the
100 Percent Clean Energy Act, calling for 100 percent of total retail sales
of electricity in California to come from eligible renewable energy and zero-carbon
resources before 2046.) On a personal level, commit to conserving energy
wherever possible. Walk, bike, ride public transit, and carpool instead of
driving alone. Reduce your waste by thinking before you buy something. Conserve electricity, gas, and water
(which takes energy to heat, pump, and treat) at home and work. Eat less meat, since livestock farming produces
high amounts of greenhouse gases. And help the ocean cope by reducing other pressures on marine organisms by consuming only
seafood that has been fished or farmed sustainably, picking
up trash in your neighborhood and at the beach, practicing smart use of pesticides and fertilizers, and cleaning
up after pets. Research is ongoing to study how marine organisms such as seagrass and kelp locally reduce dissolved CO2, so protecting and restoring these coastal habitats
may be an important tool in dealing with ocean acidification.
Learn more about ocean acidification:
- State of California Ocean Acidification Action Plan, California Ocean Protection Council and the California Ocean Science Trust
- NOAA Ocean Acidification Program
Carbon Dioxide Time-Series, showing correlation between atmospheric CO2, CO2 in ocean, and ocean pH
- The Keeling Curve, a daily record of atmospheric
carbon dioxide from Scripps Institution of Oceanography at UC San Diego, recorded from Mauna Loa Observatory
- Climate Change: How do we know? Atmospheric
CO2 graph and additional information from NASA
- West Coast Ocean Acidification and Hypoxia Science Panel, Major Findings, Recommendations, and Actions, California Ocean Science Trust, 2016
- Evidence for
upwelling of corrosive "acidified" water onto the Continental Shelf, 2008 publication of Pacific Marine Environmental
Laboratory, National Oceanic and Atmospheric Administration (Alternative online source)
State Blue Ribbon Panel on Ocean Acidification, 2012
- Video from Cal Academy explaining
- Video from
The Ocean Conservancy on ocean acidification in Washington State
- Ten Ways States Can Combat Ocean Acidification (and Why They Should), Ryan P. Kelly and
Margaret R. Caldwell, Harvard Environmental Law Review, 2013
Resources for educators:
Ocean Acidification explained as a Comic:
See below for the text content of this comic.
This comic was co-produced by Years of Living Dangerously, a SHOWTIME climate change documentary series,
and Symbolia, a magazine where
"comics and journalism meet." Find more information at symboliamag.com and yearsoflivingdangerously.com.
Text Content of the comic:
"SHELL SHOCK" by Andy Warner and Lauren Sommer
Increasing levels of CO2 in the world's oceans threaten everything from shellfish farms
to the beautiful coral reefs that are home to a quarter of all marine species.
The higher levels of CO2 are making seawater more acidic. That makes it harder for animals that
build shells to make their homes, which can lead to disease and die-offs. And there are a LOT
of animals that build shells.
Tiny shell-based organisms are part of the diet of big marine animals like salmon. Entire
ecosystems are at risk. This increased acidity can be traced to one primary source...us.
Here's how it all works:
Carbon Dioxide (CO2) is released by human activity in to the atmosphere. About 30% of that
CO2 ends up in oceans, rivers, or lakes. The CO2 dissolves in the ocean and reacts with seawater
to form Carbonic Acid. That lowers the pH, increasing the acidity of the ocean. But
it doesn't stop there.
Oceans are already saturated with another compound called Carbonate. Organisms use Carbonate to
create shells and structures.
The problem is this:
When Carbonic Acid from the CO2 breaks down, it release hydrogen ions. Those hydrogen ions then
bind with the Carbonate that organisms need. That makes Carbonate unavailable, which means
that it can't be used to build new shells. And existing shells can actually dissolve. Oceans
are about 30% more acidic now than when the industrial revolution began.
The increasing acidity of the oceans is already having a human impact. "There's a perfect storm
of events. Changes are happening much too quickly," says Terry Sawyer, co-owner of Hog Island Oyster
Company in California. A few years ago the hatcheries in Oregon and Washington which supply
him with baby oysters began seeing huge tanks full of larvae die off. The hatcheries were
filling their tanks with sea water. That turned out to be a problem. The increased acidity of the
ocean, combined with a natural upwelling of low pH water off the Pacific coast devastated
the young oysters. Just like the oysters he grows, Terry Sawyer says he'll have to adapt to the
rapidly changing environment of the oceans. "We don't have the luxury to look the other way.
Our challenge is to figure out where we can grow, what species we can grow, what adaptations we
can implement. We are having an effect on the oceans. We've got to start doing
something about it."
From Symbolia, Years of Living Dangerously