<human>:  What is the el Niño-Southern Oscillation and what affect does it have on climate?
<bot>: The El Niño-Southern Oscillation (ENSO) is a naturally-occurring phenomenon in which the sea surface temperatures in the equatorial Pacific Ocean oscillate above or below normal. This oscillation is associated with periodic shifts in the prevailing winds and air pressure in the region, leading to large-scale changes in precipitation, atmospheric dynamics and the climate of the region. These shifts of the ENSO cause effects around the world, some of which can be climate-related, such as wetter or drier conditions in certain regions and periods of stronger, or weaker trade winds. These conditions can lead to climatic extremes such as floods or droughts, and may even alter the course of global warming.