281
See also: Global warming 202–203 ■ Pollution 230–235 ■ Endangered habitats
236–239 ■ Acid rain 248–249 ■ Halting climate change 316–321A
dding carbon dioxide (CO 2 )
to the air not only triggers
climate change but also
makes the oceans more acidic. So
far, the oceans have buffered the
worst effects of global warming,
absorbing up to half of the carbon
dioxide added to the atmosphere by
human activity. However, the gas
alters the oceans’ chemistry.
In 2003, American climate
scientists Ken Caldeira and Michael
E. Wickett investigated the effectsof CO 2 pollution on the oceans.
They took samples of seawater
from around the world, and found
that the acidity had increased
measurably in the past 200 years
of industrialization. They coined
the term “ocean acidification” and
predicted that this change could
accelerate over the next 50 years,
with damaging results.
Many sea creatures rely on the
natural alkalinity of seawater to
maintain carbonates for building
their shells and skeletons. Even a
slight decrease in alkalinity seriously
disrupts growth, especially for
sensitive creatures such as corals
and plankton. Acidification might
wipe out corals within decades; if
they go, so do the reef ecosystems.
Phytoplankton are the foundation
of the ocean food web, and are
vital to maintaining global
oxygen levels.
Ocean acidification is far harder
to reverse than the atmospheric
effects of CO 2 emissions, and its
devasting impact on biodiversity,
fisheries, and food security remains
a serious concern. ■THE HUMAN FACTOR
IN CONTEXT
KEY FIGURES
Kenneth Caldeira (1960 –),
Michael E. Wickett (1971–)BEFORE
1909 Danish chemist Søren
Sørensen develops the pH
scale for measuring acidity.1929 American biologists
Alfred Redfield and Robert
Goodkind discover that excess
carbon dioxide in water
suffocates squid.1933 German chemist
Hermann Wattenberg makes
the first global survey of ocean
acidity, as he analyzes results
from the Atlantic expedition
of the Meteor research vessel.AFTER
2012 In the US, oceanographer
James C. Zachos and his
colleagues use fossil evidence
from marine sediments to
show that past acidification
of the ocean has led to mass
extinctions of sea creatures.IMAGINE TRYING TO
BUILD A HOUSE WHILE
SOMEONE KEEPS
STEALING YOUR BRICKS
OCEAN ACIDIFICATION
Most carbon dioxide released
into the atmosphere as a result
of burning fossil fuels will be
absorbed by the ocean.
Ken Caldeira and
Michael WickettUS_280-281_Amphibian_Ocean_acidification.indd 281 12/11/18 6:26 PM