1.  El Niño and La Niña: Their Impacts on Global Climate and Geomorphic Systems Kathy Lipschultz

2. What is ENSO?  ENSO = El Niño-Southern Oscillation  La Niña = cold equatorial Pacific  El Niño = warm equatorial Pacific  Interannual variation in sea surface temperatures and atmospheric conditions over the tropical eastern Pacific Ocean  Events last 1-2 years and begins between December and February

3. During ENSO events  El Niño  SST (Sea Surface Temperature) increases, easterly trade winds weaken in the equatorial Pacific.  Currents move surface water away from the western coast South America more slowly  Thermocline flattens  During La Niña, SST decreases, and results in opposite effects

4. Driving Factors  Coupled interaction between the ocean and atmosphere  Madden-Julian Oscillation  easterly winds  Kelvin waves  Volcanic eruptions  Affect atmospheric/oceanic circulation  Changes SST

5. Climatic Consequences  Asia  El Niño increases rainfall in extratropics, weakens summer monsoons, causes droughts in SE  La Niña causes floods in SE  Africa  Dipole in rainfall

6. Climatic Consequences (cont.)  North America  El Niño = more severe weather in southern U.S., dry monsoon seasons in Mexico  La Niña = 66% chance of ≥2 hurricanes hitting cont’l U.S., wet monsoon seasons  South America  El Niño = droughts in Brazil in March, decreased rainfall in Amazon

7. Geomorphic Implications  Damage to coasts and coral reef ecosystems  Movement of dunes, glaciers, and mass wasting in heavy-rain areas  Change in streamflow, sediment yield, and water levels in lakes

8.  The erosion of Pacifica Cliffs in January 2016 from increased storm activity during El Niño

9.  From slope failure after heavy rain  ~$4,000,000 of damage – the most expensive landslide in U.S. history Thistle slide, Utah, 1983

10.  A flooded football field in Arnold, Missouri after the Meremec River avulsed following days of El Niño-induced rainfall (January 2016)

11. In summary...  ENSO has consequences for climate and, as a result, geomorphic systems  These consequences are numerous and global in scale