El Niño Southern Oscillation (ENSO) is a climate pattern that occurs across the tropical Pacific Ocean approximately every 3 to 7 years, characterized by the warming of eastern Pacific Ocean waters and low atmospheric pressure in that region. El Niño events can have widespread global impacts, including severe droughts in some areas like the Philippines as well as floods in other regions such as California during the strong 1997-1998 El Niño when abnormally high sea levels caused hundreds of millions in flood damage in the San Francisco Bay area.

1. The Impact of El Nino
on Global Hazards

2. What is El Nino?
El Niño Southern Oscillation, or ENSO,
is a climate pattern that occurs across the
tropical Pacific Ocean on average every
five years, but over a period which varies
from three to seven years.
It is characterised by the warming of the
surface of the eastern Pacific Ocean and
the dominance of low pressure in the
atmosphere in that region.

3. Frequency of El Nino Events

4. Normal
El Nino

5. Normal

6. El Nino

7. El Nino Sea Surface
Temperature
Normal Sea Surface
Temperature

9. Global Impact of El Nino

10. Legend: Potential AreasLegend: Potential Areas
UnderUnder
Severe drought impactsSevere drought impacts
Drought impacts with majorDrought impacts with major
losseslosses
Moderate drought impactsModerate drought impacts
Near normal to above normalNear normal to above normal
conditioncondition
Way above normal conditionWay above normal condition
Flood damageFlood damage
Severe flood damageSevere flood damage
Analysing the Impact of El Nino on Droughts in The Philippines

12. Impact of El Nino On California

14. Flooding in San
Francisco
During the winter of 1997-
98, wind-driven waves
and abnormally high sea
levels significantly
contributed to hundreds
of millions of dollars in
flood and storm damage
in the San Francisco Bay
region. Recent analyses
by U.S. Geological
Survey (USGS) scientists
of nearly 100 years of
sea-level records
collected near the Golden
Gate Bridge found that
these abnormally high
sea levels were the direct
result of that year's El
Niño atmospheric
phenomenon.

15. The Impact of El Nino
on Global Hazards