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Ocean and Climate
Adopted from NASA
http://oceanmotion.org/html/backgroun
d/climate.htm#rain
(By: Robert Stewart)
Earth and the Ocean
• Water covers nearly 71% of
Earth’s surface
• The ocean stores huge
quantities of energy, and heat
exchange between the ocean
and atmosphere drives the
winds and atmospheric
circulation around the world.
– These winds in turn drive ocean
surface currents
• Ocean has moderating effect
on climate
– Absorbs carbon dioxide and
excess heat
Source: NASA Earth Observatory
Ocean Life
• Without an ocean, Earth
might be more like
Venus
– Most abundant gas in
Venus’s atmosphere is
carbon dioxide
– Surface is hot enough to
melt lead
• Carbon dioxide only
makes up 0.038% of
Earth’s atmosphere
The Planet Venus Source: NASA Planetary
Photojournal
– May be increasing because
of burning fossil fuels and
smaller tropical rainforests
Ocean Life
• The differences between the atmospheres
Earth and Venus can be linked back to
ocean life
– Photosynthetic organisms, whether they are
single-celled phytoplankton floating on or
near the ocean surface or plants growing on
land, take up carbon dioxide from the
environment and use the sun’s energy to
build carbohydrates.
– This process releases oxygen, which is the
source of oxygen in the atmosphere.
Pictures from Phytoplankton, Source: NASA SeaWiFS
Cycle Created by Photosynthetic
Ocean Organisms
• Other organisms eat primary producers 
carbohydrates passed through food
chain organisms use carbs as fuel and
structural building blocks  organisms
break down carbs for energy using cellular
respiration (uses oxygen and releases
carbon dioxide)  organisms die,
decomposers break them down
Without Decomposition…
• Some parts of
organisms don’t
decompose
– Plankton, coral and
mollusks build
skeletons/shells of
calcium carbonate
– Pressure and heat
cement some of these
and over millions of years
rocks such as limestone,
marble and dolomite are
created
Life in the ocean has produced vast layers of
limestone and marble rock. El Capitan, Capitan Reef,
Guadaloupe Mountains National Park, Texas. This is a
coral reef from the Permian period.
Credit: Mark Eberle, Fort Hayes State University.
Without Decomposition in the
Ocean
• Sediment buries remains of
organisms
• Deprived of oxygen needed for
decomposition, these remains
may transform into deposits of
coal, oil and natural gas
– This locks up more carbon
• When we burn these fossil fuels
for energy, we release the
carbon dioxide into the
environment
The Ocean and Heat
• The ocean absorbs
heat when the air is
warm and releases
heat when air is cool.
• In the tropics, where
energy from the sun is
at its greatest, the
exchange of heat
between ocean and
atmosphere drives
much of the global
atmospheric circulation
For scientists to understand climate, they must also determine what
drives the changes within the Earth's radiation balance. From March
2000 to May 2001, the CERES instrument measured some of these
changes and produced new images that dynamically show heat (or
thermal radiation) emitted to space from Earth's surface and
atmosphere (right sphere) and sunlight reflected back to space by the
ocean, land, aerosols, and clouds (left sphere).
The image above is from April 2001.
Credit: CERES Press Release Images, NASA
The Ocean and Heat
• Sunshine heats up surface of land and
ocean, but heats the ocean more slowly
– Most of the heating of the ocean takes place
in the tropics
– While ocean surface currents carry some of
the heat north and south away from the
tropics, the bulk of the energy is released
back into the atmosphere
– Some heat is released in the form of infrared
radiation
– Greenhouse gases, most notably water vapor
from the ocean, but also carbon dioxide, trap
this heat, warming the atmosphere
Sea surface temperatures for spring 2004.
Credit: Norman Kuring, GSFC, NASA
The Ocean and the Atmosphere
• The most important
mechanism is
latent heat release
or evaporation.
Over the ocean,
latent heat is the
engine that drives
atmospheric
circulation
The water cycle circulates both water and
energy throughout Earth’s system. The cycle
begins with evaporation of water from the
surface. Evaporation of water is the source of
atmospheric moisture that carries heat energy
away from Earth’s surface.
Credit: The Asian Monsoon CD, GSFC, NASA
Water Cycle and Atmosphere
• As the sun beats down and the ocean
warms, water from the upper layer of the
ocean evaporates  The conversion of
liquid to vapor requires a lot of energy, so
evaporation cools the top layer  Trade
winds carry the vapor to the area where
the north and south trade winds converge
called the intertropical convergence zone
(ITCZ)  There the moist air rises and
cools 
Water Cycle and Atmosphere
Continued
• The water vapor condenses on tiny particles
suspended in the air called nuclei, forming
clouds  This condensation releases energy,
heating the surrounding air  The warmed air
then rises higher, drawing up more moisture
from the ocean More vapor then condenses
higher in the atmosphere and releases more
heat, causing the air to rise further, and so on
 The result is towering clouds that dump up to
five meters of rain per year over some parts of
the tropical ocean
Evaporation and Condensation
Credit: The Asian Monsoon CD, GSFC, NASA
Hurricanes
• This same process fuels hurricanes. At the
centers of these storms, moist air rising from the
warm ocean heats up as the vapor condenses.
Warm air is less dense, so the atmospheric
pressure drops. More moist air then rushes in off
the ocean due to the pressure gradient, rotating
counterclockwise due to the Coriolis effect. This
air rises up, and condensation releases more
heat, intensifying the storm and further lowering
the pressure. (Hurricanes generally don’t form
close to equator because the Coriolis effect is
weak.)
Earth’s Circulation Systems
Illustration Credit: Tinka Sloss, New Media Studio, Inc.
• The major circulation
systems of the Earth
are illustrated above.
On or near the
equator, where
average solar
radiation is greatest,
air is warmed at the
surface and rises.
This creates a band
of low air pressure,
centered on the
equator known as the
intertropical
convergence zone
(ITCZ). The
Intertropical
Convergence Zone
draws in surface air
from the subtropics.
The Ocean and Climate Change
• The ocean is a buffer for climate change
– Ocean can hold 40 times more carbon dioxide
than the atmosphere
– Carbon dioxide dissolves in cold water near
the Arctic and Antarctic
• In the winter, the cold water sinks as part of
ocean’s overturning circulation and CO2 is carried
deeper
• After 100s of years, winds and tides pull water
back to the surface and CO2 is released again
Ocean and Climate Change
• Ocean water also
absorbs tremendous
quantities of heat
• As the atmosphere
warms due to the
buildup of
greenhouse gases, it
transfers some of this
heat to the ocean,
slowing the pace of
climate change
The global carbon cycle shows the carbon
reservoirs in billions of tons of carbon and
exchanges between the reservoirs in billions of
tons/year. The numbers on the figure are annual
averages over the period 1980 to 1989.
Source: Vital Climate Graphics, United Nations Environment
Programme, UNEP/GRID Arendal.
Marine Organisms and Cloud
Formation
• Many plankton release a chemical
called dimethyl sulfide into the
atmosphere
Phytoplankton in the ocean produce
dimethyl sulfide (DMS) that is
converted to sulfate aerosols (SO4),
which influence the amount of
sunlight reflected by clouds.
– This chemical undergoes a series of
reactions in the air to form sulfate
particles
– Vapor condenses around these
particles to form clouds
– These clouds have smaller droplets
than other clouds
– hey therefore are brighter and reflect
more sunlight back out into space,
preventing the sunlight from reaching
and heating Earth’s surface
The Ocean and Rain
• Some of the most consequential rainfalls are
generated by the seasonal monsoons, especially
over Asia
– The heavy monsoon rains over much of Asia not only
provide these countries with critical moisture, they
release tremendous amounts of latent heat which
helps drive atmospheric circulation
• A similar process fuels the North American
monsoons, which provide important summer
rainfall to the southwestern United States and
northwestern Mexico.
–
Visit http://www.vets.ucar.edu/vg/CCM3T170/index.shtml for video
Everything is Connected!
Some of the many ways
the ocean influences
climate by exchanging
heat, water, and
chemical compounds
with the atmosphere.
Source: Climate Change Impacts on the United States