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How do ocean currents contribute to the change in
climate?
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Question Date: 2005-05-22 | | Answer 1:
First off, certain famous ocean currents have
well-known effects on climate. Consider the Gulf
Stream. The climate in Northwestern Europe (the UK
especially) is much more mild than it is directly
across the Atlantic in Canada and the Northeastern
US. There can be up to a 30-40 degree (Fahrenheit)
air temperature difference in January between
these two areas. The Atlantic Ocean near Canada is
locked in ice in winter but the Atlantic Ocean
near England is not. It is thought that the huge
temperature difference is due to the Gulf Stream,
one of the strongest currents in the ocean, and
one of the best studied. (Ben Franklin was one of
the first people to map this current. You can
check out information on Gulf
stream History.)
The Gulf Stream brings
warm water from the Carribean and Florida north,
along the coast of the US, and then east across
the Atlantic to Europe. Because it takes a
right-hand turn somewhere around North Carolina,
the warming effect of its waters misses the
Northeast US and Canada, but does reach England
and Ireland. Take a look at some maps of the The
Gulf stream and maps.
Wheither
or not you think that the relatively mild climate
in England, Scotland, Wales, Ireland and Northern
Ireland is due to the direct effect of the warm
water in the Gulf Stream, or to the indirect
effect of The Great Ocean Conveyor Belt
("thermohaline circulation"), of which the Gulf
Stream is a part, either way the warming is partly
caused by ocean currents. If the Gulf stream was
to slow down considerably (as it has in the past),
then winters in Europe would become very cold. The
last time this happened, from 1450-1900, it was
called The
Little Ice Age.
There is some concern
that current global warming caused by rising
carbon dioxide concentrations will cause the polar
ice cap to melt and slow down the Great Ocean
Conveyor Belt, thus slowing down the Gulf Stream
and sparking a cooling event in Western Europe.
This is the (tiny bit of) science behind the movie
"The Day After Tomorrow". Many scientists think
this is unlikely, but recent research shown that
past ice ages have been linked to slow downs in
the Great Ocean Conveyor Belt. Check out Abrupt
Climate Change.
The Gulf Stream is just
one example of how ocean circulation affects
climate. It is a more complicated story. Winds are
an important force driving ocean currents. Winds,
in turn, are partly driven by differences in heat
from one part of the globe to the next. As global
warming affects the global heat budget, it will
alter the strength and direction of winds, which
will alter the strength and direction of the major
ocean currents. We already see evidence for
changes in ocean circulation due to global
warming, but I don't think anyone knows enough
about the complex interaction of winds, currents
and the global heat balance to predict what will
happen as more and more warming occurs. As ocean
currents change (and they will), not only will
climate change, but marine ecosystems will change
as well, with potentially dramatic effects on all
ocean life, as well as on the human food supply.
(More than 1 billion people rely on fish as their
primary source of protein.) | | Answer 2:
The contribution of the ocean currents to the
climate exists, and it also works in the opposite
direction. I mean, the climate also contributes to
ocean currents. Ocean waters are constantly on the
move. How they move influences climate and living
conditions for plants and animals, even on
land. Currents flow in complex patterns
affected by wind, the water's salinity and heat
content, bottom topography, and the earth's
rotation. Surface water movement takes place in
the form of currents. Currents move ocean water
horizontally at the ocean's surface. Surface
currents are driven mainly by the wind. Other
forces such as the Coriolis effect and the
location of landmasses do affect surface current
patterns. The Coriolis Effect explains how the
earth's spin causes the wind to curve. The wind in
the northern hemisphere curves to the right and
the wind in the southern hemisphere curves to the
left. In fact, huge circular patterns called
current gyres can be seen when looking at the
world's ocean currents. From the equator to middle
latitudes, the circular motion is clockwise in the
Northern Hemisphere and counterclockwise in the
Southern hemisphere. Near the poles of the Earth,
there is a tendency for the gyres to flow in the
opposite direction. This circulation of water
helps spread energy from the Sun. The Sun warms
water at the equator and then water and heat are
transported to higher latitudes. An example is
El Nino. El Nino is a name given to the occasional
development of warm ocean surface waters along the
coast of Ecuador and Peru. In El Nino years, the
Equatorial counter current intensifies in the
Pacific Ocean.This current flows towards the east,
and it is a partial return of water carried
westward by the North and South Equatorial
currents. The effect of El Nino brings changes of
weather raising or lowering air temperature, and
amounts of rain. These factors contribute to
change the weather in different places and in
different forms. | | Answer 3:
Currents flow in complex patterns affected by
wind, the water's salinity and heat content,
bottom topography, and the earth's rotation.
Upwelling brings cold, nutrient-rich water from
the depths up to the surface. The earth's rotation
and strong seasonal winds push surface water away
from some western coasts, so water rises on the
western edges of continents to replace it, which
is why the ocean is so much colder on the east
coast than the west coast. Marine life thrives in
these nutrient-rich waters. Colder or saltier
water tends to sink, so you can imagine that the
waters off the coast of Antarctica are really
cold. A global "conveyor belt" sets in motion
when deep water forms in the North Atlantic,
sinks, moves south, and circulates around
Antarctica, and then moves northward to the
Indian, Pacific, and Atlantic basins. It can take
a thousand years for water from the North Atlantic
to find its way into the North Pacific. Oceans
store a large amount of heat, so small changes in
ocean currents can have a large effect on coastal
and global climate as they carry enormous amounts
of heat north and south. | | Answer 4:
Ocean currents move warm and cold bodies of water
around. Water has a specific heat capacity
thousands of times that of air, and as a result
are able to chill or heat the air over them, as
well, as are the source of vapor that becomes
clouds and precipitation.Simply enough, the
Earth's air-flow patterns are atmospheric, but the
air temperature and even moreso the precipitation
depends on ocean currents. | | Answer 5:
Oceans play a HUGE role in redistributing heat
around the globe. Ocean surface water that is
heated by the sun near the equator eventually
makes its way to the high latitudes where it cools
off. When it is cooled, it sinks. Eventually,
that cooled water makes its way back to the
equator where it wells up and becomes surface
water again. The whole cycle then repeats itself.
This system of upwelling, heating, cooling, and
downwelling is called the global thermohaline
circulation system. Itsprimary influence is to
transfer heat from the equator to the
highlatitudes. One fear related to global warming
is that rapidly melting polar ice sheets could
cause this circulation system to cease. Melting
of ice sheets delivers huge influxes of fresh
water to the polar oceans. Because freshwater is
less dense than sea water, it sits on the surface
of the oceans and prevents the sinking that is
necessary to drive the circulation system. The
effect of this is that the higher latitudes
(England, for example) would become much colder
because no warm surface water would be brought to
the poles and the lower latitudes (around the
equator) would become warmer because there would
be no upwelling of cold water. Click Here to return to the search form.
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