Yes, temperature gradually declined. Has Earth been through

      Yes, it is possible to
reverse ocean acidification with aquatic organisms, such as phytoplankton,
seaweed, seagrass, mangroves, etc. Aquatic organisms can use carbon-dioxide and
convert it to oxygen through photosynthesis, thereby reducing the total amount
of carbon dioxide on Earth.

Is it possible to reverse
ocean acidification, and if so, how can we do it?

       Yes, about 56 million years ago, Earth
experienced what is called the Paleocene-Eocene Thermal Maximum. It is believed
to be caused by a sudden release of methane into the atmosphere During this
event, Earth’s temperature increased by five degrees Celsius or nine degrees
Fahrenheit. Some areas in the Artic had temperatures as high as twenty-three
degrees Celsius, or seventy-three degrees Fahrenheit! Several species went
extinct during this period- both marine and terrestrial. The pH of the ocean
lowered dramatically,
and the water became extremely acidic due to the high concentration of
dissolved carbon. This led to the shells of marine organisms dissolving. So
many shells dissolved, that the originally white sediment turned red! However,
the Paleocene-Eocene Thermal Maximum only occurred for a couple hundred
thousand years and for the next millions of years afterward, the temperature
gradually declined.

Has Earth been through these
kinds of conditions (ocean acidification) before?

    Coral reefs are fragile ecosystems that are especially affected by
ocean acidification. Ocean acidification slows the growth of existing corals by
dissolving the skeletons, and it also slows the growth of new corals. Ocean
acidification also increases corals’ vulnerability to erosion. Additionally,
corals require saturation levels of aragonite over 4 in order to prosper. However,
ocean acidification has dramatically lowered levels of aragonite in oceans.
Now, the average aragonite saturation level is 3.8, down from 4.6. If aragonite saturation levels fall below 1, then
corals and shells will completely dissolve. Also, animals with shells, such as
mussels and oysters, are affected by ocean acidification because their shells
weaken due to a decreased presence of calcium carbonate. Weakened shells leave
the organisms extremely vulnerable to being eaten by other organisms. Ocean
acidification also affects fish. Fish will absorb the carbonic acid, and the pH
of their blood will lower by 0.2 to 0.3 units. If the pH of blood drops this
much in humans, then people might die. A drop of pH in fish will cause the fish
to overwork and expend a lot of energy on excreting the carbonic acid. This
means that the fish won’t spend as much energy finding food, escaping from
predators, and reproducing. As a result, the fish will die earlier, and their
population will dwindle. Also, the change in pH can change the brain of a fish,
can prevent it from sensing predators, and finding its way home. As you can
see, ocean acidification is extremely harmful to almost all organisms.

What are the effects of
ocean acidification?

            About one third of the carbon dioxide
that humans produce is absorbed by the oceans. When the carbon dioxide is
dissolved in the water, carbonic acid forms, leading to lower pH levels. Lower
pH levels indicate that the water is becoming acidic, which is extremely harmful
for marine aquatic ecosystems. The lowering of the pH of oceanwater is called
ocean acidification. For millions of years, the pH of oceans was 8.2, but it’s
acidity has increased by 25% in recent years. The current pH of oceans is 8.1,
and is projected to drop a further 0.5 units by 2100.

What is ocean
acidification?

        
pH is the measure of the concentration of hydrogen ions in a
substance. A pH of 7 is considered neutral, whereas a pH below 7 is considered
acidic, and a pH above 7 is considered alkaline.  

What is pH?