|USGCRP Home Library Global Change Research Highlights Predicting El Nino & Other Climate Variations||| Search|
12 October, 2003
Predicting El Niño and
Progress in predicting El Niño, months and occasionally a year in advance, has been facilitated by nearly twelve years worth of research coordinated by the United States Global Change Research Program.
Improved ENSO forecasts enable state and federal policymakers and ordinary citizens to make informed decisions.
Further research is vital to answer the over-arching, critically important questions: how will the global climate system evolve over the next century and how will human civilization adapt?
major announcement on March 7, 2002 by scientists with the National
Oceanic and Atmospheric Administration (NOAA) that another "El Niño"
episode appears to be taking shape indicates the importance associated
with forecasting this large-scale, often disruptive climatic event months
ahead of time. Fifteen years ago, predictions of El Niño were left
largely to adventurous researchers. Progress in predicting El Niño,
months and occasionally a year in advance, has been facilitated by nearly
twelve years worth of research sponsored by NOAA, NASA, the National
Science Foundation, and other federal agencies, and coordinated by the
United States Global Change Research Program
|Flooded area in Lakeport, California as a result of the 1998 El Nino event.|
There are many case
studies of regional ENSO-related impacts that have motivated the
development of seasonal climate forecasts for specific regions in advance
of ENSO events. In Florida, El Niño years bring flooding rains in prime
agricultural areas. Significant impacts are found on the sugarcane,
tomato, bell pepper, and snap bean crop yields, not to mention on the
state's famed citrus fruit industry. Dr. Jim O'Brien at Florida State
University cites the example of how ENSO seasonal forecasts enabled a few
potato farmers in Florida to mitigate, through relatively inexpensive
field preparations, the otherwise costly impacts of flooded fields that El
Niño-related heavy rains usually bring. In California, the state
established the El
Niño Information web site to provide citizens information, including
forecasts and predictions, impacts and effects, and contacts to the
various state agencies tasked with assorted preparations in numerous
sectors (e.g. emergency response, food and agriculture, public utilities)
for the anticipated impact of this El Niño. Local officials up and down
the coast convened public hearings to ensure El Niño community
|US Senator Barbara Boxer (Democrat, California) addresses reporters at the El Nino Summit on 14 October 1997, Santa Monica, California.|
It was only
through careful observations, development of prediction models, and
production of climate forecast products made possible by the wide range of
USGCRP-facilitated research, that both ENSO climate forecasts and
assessments of the societal impacts are now even possible.
But the work is
evidence has indicated that variability of the other tropical oceans
influence the climate of
surrounding continents. The U.S.
Climate Variability and Predictability program (CLIVAR) -- one of the
components of the USGCRP that focuses on these types of natural variability-- faces stiff
challenges. These include:
the lead-time and skill of ENSO ocean temperature predictions --
Currently the best models can predict six months in advance (out to a
year in special cases) if an ENSO event is likely; however,
predictions of how ocean temperatures will change during the course of
an ENSO event are inadequate. This fundamentally limits the capabilities
to build better climate-forecast models. In addition, there is the
unanswered question of how ENSO is affected by longer-term trends in
the global climate system.
better climate-forecast systems -- Even if ocean temperature
predictions were perfect, models used to forecast regional climate
effects associated with these changes need vast improvement in order
to be able to deliver
useful products to elected officials, policymakers, and ordinary
citizens. Improved climate forecast models that consider how the land
influences the climate, as well as other critical components of the
climate system, must be developed. Such a system needs to be able to
faithfully predict the likelihood of extreme (e.g. droughts, floods,
heat waves) events in particular regions.
and predicting other tropical variability -- Variability of the
tropical Atlantic is thought to be related in part to the strength of
the trade winds and to tropical convection (thunderstorm activity).
Tropical Atlantic Variability (TAV) has been shown to influence the
climate of North and South America and other regions. Likewise, the
variability of the Indian Ocean amy have impacts on South Asia and
portions of eastern and southern Africa. Yet we do not understand the
fundamental physical mechanisms governing these modes (patterns) of
variability, nor the extent to which these patterns impact our ability
to make predictions. We do recognize that interactions between the
ocean, atmosphere, and land surfaces are very important.
the interconnectedness between tropical and mid-latitude variability
-- Evidence shows that there is a connection between ENSO, an
ocean-air phenomenon of the tropical Pacific, and TAV. Likewise, there
appears to be relationships between them and other types of
variability outside of the tropics. An example is the connection of
ENSO and TAV to another type of natural variability in the atmosphere
called the North Atlantic Oscillation (NAO). The NAO is a see-saw
pattern in air pressure across the Atlantic Ocean between the Azores
and Iceland that has a profound effect on the position of the storm
track across eastern North America and Europe -- with resulting big
effects on the winter weather in these places. All of these need to be
explored to improve climate forecast model capabilities and skills.
in all these areas is vital to determine the over-arching, critically
important of question of how the global climate system will evolve over
the next century and addressing the question of how human civilization
will have to adapt. And USGCRP has a key role to play in coordinating the
various components of all this important research.