Extreme and Connected Climatic Phenomena
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reader!
It
follows one article published day (12/05) in the english website of the Agência
FAPESP highlighting the extreme and connected Climatic Phenomena.
Duda
Falcão
Extreme
and Connected Climatic Phenomena
By Washington
Castilhos, in Rio de Janeiro
December
5, 2012
Agência FAPESP – Teleconnections are remote relationships.
Events on one side of the planet can affect what happens on the other side. One
example is El Niño, a climatic phenomenon of tropical origin caused by abnormal
warming of the waters in the Pacific Ocean. Some of El Niño’s effects are
drought in Brazil’s Northeast and heavy rains in the South.
El Niño’s origin provides another example of teleconnection: the cause
of the phenomenon—warming of the western Pacific—could be related to higher
temperatures of the Indian Ocean.
According to José Marengo, a researcher at the National Institute for
Space Research (INPE) Earth System Science Center, identifying teleconnections
and analyzing their influences on atmospheric circulation could be useful in
understanding abnormal events across the globe.
“Teleconnections are associated with natural causes and not man’s
influence. Over a 100-year period, oscillating patterns can be observed that
affect the climate of certain regions—like El Niño, the Pacific Decadal
Oscillation and the North Atlantic Oscillation. For example, today we are in a
phase where the Pacific Ocean is cooler and the Atlantic plays a more active
role,” said Marengo, who is a member of the Intergovernmental Panel on Climate
Change (IPCC) for the Symposium on the Relationship Between the Oceans and
Continents and its Role in Global Change held by the Brazilian Academy of
Sciences (ABC) in October.
Recent studies have shown that El Niño has different facets. In
analyzing the phenomena occurring between 1900 and 2012, a group led by Edmo
Campos, professor at the Universidade de São Paulo Oceanographic Institute
(IO-USP), observed 14 drier events and 14 wetter events.
“The explanation for this comes from the South Atlantic, which plays a
determining role in whether El Niño will be ‘wet’ or ‘dry’. A series of events
influencing the global climate occurs in the Atlantic. El Niño doesn’t depend
on the Atlantic, but its impacts will vary depending on the interactions
between the Atlantic and the Pacific,” said Campos, who coordinates research
projects funded by FAPESP such as “Impact of the Southern Atlantic on the global overturning circulation
(MOC) and climate (SAMOC)”.
According to Campos, observations and models show that variations in the
Meridional Overturning Cell, or MOC, are strongly related to significant
changes in climate. Until now, most observations have focused on the North
Atlantic.
“However, studies show that the South Atlantic isn’t merely a passive
conductor of water masses formed in other regions and that changes in the
return flow of the MOC in the South Atlantic could significantly impact the
regional and global climate,” Campos told Agência FAPESP.
“So, a weak MOC results in a warmer South Atlantic, which can mean more
rain in the Brazilian Northeast. El Niño has assumed a more passive role, while
the Atlantic Ocean today has a more active one,” he pointed out.
Extreme Events
Björn Kjerfve, the president of Sweden’s World Maritime University
(WMU), stresses that the oceans play a predominant role in any climate change
scenario. “The oceans are regulators of the planet’s climate. If Earth’s
average temperature rises by one degree, a certain amount of ice will melt,”
Kjerfve said at the symposium.
Warming of the South Atlantic resulted in the Catarina cyclone, which
struck southern Brazil in March 2004. A warmer North Atlantic caused Hurricane
Sandy, which recently hit the East Coast of the United States. “Cyclones are
closely related to the temperature of the sea. They only happen if the ocean’s
surface is warmer than 26 degrees. Catarina happened because, for some reason,
the water temperature was higher than average,” said Campos.
As the tendency toward warmer waters in the South Atlantic persists, Brazil
could be hit by more cyclones. “The average amount of rain has increased on the
global level along with a rise in the planet’s temperature, but we don’t know
if this will create favorable conditions for these events,” said Campos,
stressing that the IPCC reports do not offer a definitive answer as to the
occurrence of extreme events such as cyclones.
The warmer-than-normal winter and cool beginning of springtime in Brazil
in 2012 could indicate a natural adjustment. “We are at the end of a dry
period. This dry period is due to global warming, which has both natural and
anthropic causes. Human beings intensify warming. However, we can’t attribute
these anomalies exclusively to human activity,” said Campos, who coordinates
the PIRATA Project,
a cooperative program among Brazil, France and the United States created in
1995 that monitors the Atlantic Ocean.
“We know much more about the Pacific than the Atlantic. The most
significant connection between the ocean and our coast is the tropical region,
which is why it’s important to monitor the region where it bifurcates with the
South Equatorial Current. The pre-salt layer, for example, will be affected by
phenomena occurring very far away,” said the IO-USP professor.
“We still haven’t come very far in terms of oceanography. But Brazil
will be the first nation to be directly affected by changes in the South
Atlantic. We are closely connected with the Atlantic Ocean. That’s why Brazil
must be at the forefront of studies on the South Atlantic,” said Campos.
Source: English
WebSite of the Agência FAPESP
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