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La Niña event
of 1998 - 1999 had Mount Baker recording about 95
feet — the most snowfall ever measured in the United
States in a single season, according to the US
National Oceanic Atmospheric Administration.
In Feb 2008, the rare prolonged snowstorms and low
temperatures that caused havoc in Southern parts of
China are mainly related to
La Nina and abnormal atmospheric circulation,
not directly linked to climate change,
scientists said. The latest La Nina
pattern, which began in the third quarter of 2007, has picked up
strength in the past three months, with sea surface temperatures now
about 1.5 to 2 degrees Celsius colder than average over large parts
of the eastern and central equatorial Pacific Ocean, said the latest
report issued by the WMO.
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Snowy weather damages
18.6-mln-hectare forest
Freaky winter storms have
plagued southern China since mid-January 2008, leading
to widespread traffic jams, structural collapse,
blackouts and crop loss. It also killed at least 80
people and affected about 100 million residents,
according to the Ministry of Civil Affairs, China.
More pictures of intense snow
effect |
El Niño and
La Niña
are important temperature fluctuations in surface
waters of the tropical
Eastern Pacific Ocean. The Southern
Oscillation (SO) reflects the seasonal fluctuations in the air pressure difference
between
Tahiti and
Darwin,
Australia.
La Niña
is the name for the cold phase of ENSO, during which
the cold pool in the eastern Pacific intensifies and
the trade winds strengthen.
It can
trigger widespread changes in weather around the
world, including a higher-than-normal number of
hurricanes in the Atlantic.
The La Niña condition often
follows the El Niño, especially when the latter is
strong.
In the
past 20 years there have been 7 El Ninos but only
three La Ninas. Therefore La Nina effects are less
understood.
(Origin:
Mid-Atlantic
Weather Station)
La Niña causes mostly the opposite effects of El
Niño, e.g. El Niño would cause a wet period
in the Midwestern U.S., while La Niña would
typically cause a dry period in this area.
| El Niño-Southern Oscillation
(ENSO) |
|
La Niña |
|
Characterized by unusually warm ocean
temperatures in the equatorial Pacific |
|
Characterized by unusually cold ocean
temperatures in the equatorial Pacific |
|
Spanish word
meaning "the little boy", refers
to the
Christ child, because the phenomenon
is usually noticed around
Christmas time in the Pacific Ocean
off the west coast of
South America. |
|
Spanish word meaning "the little girl" |
| The most recent occurrence of El
Niño started in September 2006
and lasted until early 2007, followed by
La Nina. |
|
Formation of a weak La Niña in 2007,
strengthening in early 2008. The La Niña
condition often follows the El Niño. |
| ENSO is associated with floods,
droughts, and other disturbances in a
range of locations around the world. |
|
Associated with prolonged snowstorms and low temperatures.
|
| Cyclical 3 to 8 years.
Prevalent in the Pacific, Atlantic and
Indian Oceans. |
|
Prevalent in Pacific Ocean, cyclical
longer than 3 - 8 years |
| It is believed
that El Niño conditions suppress the
development of tropical storms and
hurricanes in the Atlantic and favors
tropical storms in the Pacific Ocean |
|
It
is believed that La Niña (cold
conditions in the equatorial Pacific)
favor hurricane formation. |
What is
the relationship between El Niño/La Niña and
global warming?
The jury is still
out on this. Are we likely to see more El Niño's
because of global warming? Will they be more
intense? These are questions facing the science
community today. Research will help us separate
the natural climate variability from any trends
due to man's activities. If we cannot sort out
what the natural variability does, then we
cannot identify the "fingerprint" of global
warming. We also need to look at the link
between decadal changes in natural variability
and global warming. At this time we cannot
preclude the possibility of links but it is too
early to say there is a definite link.
Origin:
Climate Prediction Center - NOAA
However, a study by the Environment
Illinois group may suggest indirect link: Global warming can result
in more extreme rain and snowfall as warmer temperatures allow
clouds to hold more precipitation, bringing
extremes of events.
Cool 2008 warms
climate debate
The
average global temperature for 2008 was slightly
lower than any other year since 2000, due partly
to La Nina, according to the WMO.
So is there global warming?
Critics ask.
According to
The Australian Online
Newspaper,
recent weather systems have been affected by La
Nina, not climate change, with cooler ocean temperatures generating more
rain and colder weather. The outcome is similar to
the last La Nina period in 1999 and 2000. But all
these years were still warmer than previous recorded
La Nina events. The last strong global El Nino,
which is associated with droughts, was in 1998 and
that was the hottest year on record. So that still
leaves global warming debatable.
Reference and related news:
Climate Prediction Center - NOAA
The Tech Herald
La Nina Weakening Says WMO:
News24.com Feb 18, 2009
Icy Temperatures and Snow Are
Causing Problems Across W. Europe
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